Winter 2025-2026 Offers Return to Normalcy

[40/70 Benchmark]

Verification of High Impact & Long-Duration Sunday-Monday Winter Storm

Strong Forecast Leaves Room For Improvement

Overall the Eastern Mass Weather Final Call for the major winter storm that impacted the forecast area from Sunday through Monday verified quite well.

 

However, the coastal front enhancement was somewhat misdiagnosed, as the front itself was pinned slightly closer to the coast than anticipated. The forecast for the front to penetrate into roughly the  I 495 corridor was predicated up global guidance.

 

But as it turned out, mesoscale guidance, which pinned the front closer to the coast, or along rt 128 and near I 95 on the north shore, proved to be more accurate. This is why highest amounts 

 ended up along the coast (Gloucester, MA, 27"), (Ipswich,  MA, 26"), rather than near the I 495 belt. Be that as it may, amounts of two feet, and event slightly more, were reported throughout much of northeastern Massachusetts, with a secondary on the east slope of the Worcester hills (Sterling, MA, 25.2"), as forecast.

Final Grade: A

[40/70 Benchmark]

Remarkably Well Forecast January Poised To Deliver Wintry February

Stratospheric Reflection Event To Deal Major Blow To Polar Vortex

Recent Stratospheric Reflection Event Key To Potentially Bitter Latter January

 The recent polar vortex infiltration and onslaught of severe winter weather throughout the second half of January should sound familiar to those of you who took the time to read the Eastern Mass Weather Winter Outlook last fall, which advertised that the mild, mid-month Pacific Trough Regime responsible for our January thaw would also serve as the precursor pattern to the development of what is referred to as a stratospheric reflection event. Indeed, society's understanding of the stratosphere and the role that it plays in modulating our weather is very rudimentary to say the least. The basic conceptualization is that a weak polar polar vortex makes the mid latitudes more prone to cold outbreaks, and while that is true, the method of delivery for cold to North America is multifarious in that it is not relegated to a weak polar vortex/-NAO pattern. In fact, the coldest outbreaks in the CONUS are actually triggered by a strong polar vortex and +NAO regime in what is referred to as a "stratospheric reflection event". During these stratospheric reflection events, heat is transferred upward by a Rosby wave (kink in the jet stream) over Siberia and reflects back downward of off the PV into Canada via the reflective surface posed by negative vertical wind shear in the stratosphere. ( Lee et al 2019). The study notes that these reflection events are most common during the month of January.

 

There is one reflection event on average each season, so they are by no means rare events. Reflective events are declared when the reflection index (RI), which denotes the difference in anomalous poleward eddy heat fluxes in the lower stratosphere between Siberia and Canada, exceeds 1 for 10 or more consecutive days (Lee et al 2019). Reflective events are unique occurrences in that the PV is undisturbed and initially remains strong, before being stretched by the development of Alaskan and Aleutian ridging and returning to normal strength.

 

 

 It is the stretching that delivers the cold south and eastward into the CONUS, as depicted in the "end of event" graphic above. This type of stratospheric phenomenon differs from the SSW events, in which heat propagates upward in waves that converge in the stratosphere, thus weakening the PV by decelerating and even reversing the zonal westerly winds that are ordinarily prevalent in the polar stratosphere. Reflection events also differ from SSW in that they are more favored during the westerly phase of the QBO, with 30/44 events since 1980 having occurred during a +QBO. While this ostensibly rendered such an occurrence unlikely this winter given the very strong easterly QBO that is nearing peak, the analog events of January 16, 2001 through February 18, 2001, and January 13, 2018 through February 2, 2018 were weighted heavily in the seasonal forecast given their strength as general analog seasons due to considerations discussed last fall, such as polar, ENSO  and solar implications. This is also why these two seasons are considered superior SSW analogs during the month of February.  Here is a list provided by Lee at al (2019) of the most prominent reflection events of the past 45 years, including the primary analogs of 2001 and 2018.

 

 

Courtesy Lee et al 2019

 

Note that the mean length of the process is 20 days, with 10 days being the minimum, and 60 days the maximum, per Lee et al (2019). The length of the 2001 (33 days) and 2018 (20) events were considered in the forecast for a reflection event to begin between approximately January 13th and 16th 2026, and end between about February 2 and 18th, which is consistent with the climatologically favored time frame per the research that was referenced previously. It is clear that this has indeed taken place given the latest feed back from Judah Cohen.

 "And as I have been routinely doing, looking at the wave diagnostics in Figure iv continues to display wave reflection over the weekend and into late January. For both periods shown, wave energy goes up and east over Asia, reflects off the stratospheric PV and then heads down and east over North America where the energy is re-absorbed and could potentially amplify the standing wave over North America and deliver cold air from the Arctic south, east of the Rockies. There is westward wave tilt with height over Asia and an eastward wave tilt with height over North America that is a classic signature of wave reflection. Though the eastward tilt is more pronounced in the first period compared to the second period".

 In order to better understand how the PV interacts with North American weather,  Lee at al identified four distinct weather regimes and listed their respective frequency of occurrence between the months of November and March, from 1979 through 2017, since they last longer than synoptic scale patterns and thus provide an opportunity for longer range prediction. 

Pacific Trough Pattern Precursor for Reflection Events

 Pattern recognition is paramount in the analysis and diagnosis of reflection events because the behavior of the polar vortex has predictive value on each of these regimes at both seasonal, and sub-seasonal leads, which is roughly 15-60 day in advance. "The PV strength significantly affects the occurrence and persistence of each regime and transition between regimes" (Lee at al 2019). Research by Kretschmer et al (2018) illustrated the importance of planetary wave reflection for anomalous cold across North America. This expounded on earlier work by Kordera et al (2016) that found that wave reflection born of Pacific blocking tele-connected to a down stream trough over North America. Thus the implication here is that the Alaskan ridge pattern, which is not at all connected to the PV and is actually accompanied by a +NAO, as alluded to earlier, is most conducive to reflection events and is this correlated to the most severe arctic outbreaks in the US. Lee et al (2019) refers to this type of pattern as the "Alaskan Ridge Regime" , which is similar to the  positive phase of the Tropical/Hemisphere Pattern (+TNH). The +TNH pattern is marked by higher heights over the Gulf of Alaska, the Gulf of Mexico and over the southeastern US and into the western Atlantic. 

 

 

 

Below average heights are normally anchored over southeastern Canada in association with a vortex buoyed between the Great Lakes and Hudson Bay, which is precisely what has taken place during the latter portion of January.

 

 

This particular pattern was cited last fall as the most common vehicle for cold delivery over the past decade given the increased tendency for +NAO during the winter season, which underscores the fact that climate change is certainly not prohibitive to severe cold outbreaks. That disclaimer certainly seems to have been validated based on the current arctic outbreak.

 

This is not at all surprising based on past +TNH episodes. 

Here is a composite of seasons that fit this +TNH description over the past decade or so.

 

 

Note the similarity to the -EPO predominate extra tropical Pacific pattern that was favored this winter season.

 

 

The implication here is that there was an increased likelihood for both anomalous cold outbreaks, and deviation from the predominate MC regime of the past decade during winter 2025-2026, which was also outlined last fall. Here are the four regimes as defined by Lee, accompanied by the spacial pattern of the temperature anomalies that accompany them.

 

 

The Pacific trough regime (31.6%) is the most frequent, followed by the Alaskan ridge pattern (25.1%). Note the strong resemblance between the Alaskan ridge pattern and the -EPO style extra tropical Pacific pattern expected to be predominate this winter season.

 

Below is the composite for the Pacific trough regime, which is akin to the extra tropical Pacific +EPO regime that was previously discussed.

 

This composite contains the Eastern Mass Weather extra tropical Pacific analogs of 1950-1951 and 2001-2002, as well as the La Nina analog of 2005-2006. Note the similarity to the mild interval during the middle portion of the month that was initially poorly modeled.

 

This portion of the seasonal forecast evolution was predicated upon research by Lee et al (2019), which identified the transition from this Pacific trough regime to the Alaskan ridge regime as most conducive to the type of wave propagation needed to trigger a reflection event. This is what renders the Pacific trough regime the precursor to the stratospheric reflection necessary to trigger the +TNH pattern that is now delivering an absolutely brutal stretch of winter to the region. This proved to be a remarkable extended forecasting tool given the expectation for a mid January onset of a reflection event that coincided with an influx of mild Pacific air.

 

 

Note that the pattern begins to reverse in earnest approximately 5 days after the event onset, which is precisely what has taken place.

 

Simultaneously, the anonymously strong PV reverts to normal strength, and begins to stretch due to the building Alaskan and Aleutian ridging that retrogrades from North America. 

 

In addition to the return to climo strength and above, the stretching of the PV during this reflection event has also been evident.

 

 

Although the pattern progression since the new year has evolved largely as expected, it is not without some unexpected twists. One notable deviation from the forecast was a return of -NAO blocking in conjunction with the development of this +TNH pattern, which occurred on the heels of the mid-month interval of +NAO that accompanied the Pacific trough-fueled thaw.

-NAO Flavored +TNH Pattern Will Bias Month Cold

It is evident in the annotation below that rather strong NAO blocking rematerialized after the milder period centered mid-month.

This is also on full-display in the monthly 500mb pattern to date, which has far more blocking within the NAO domain than expected.

 

 

This has consequently resulted in the PV being displaced slightly lower in latitude relative to the forecast, which is in large part why the month will end up somewhat colder than expected throughout the northeast (-1 to -3F Instead of +1 to +3 Forecast), despite a superb overall pattern diagnosis.

 

 

This also helped to ensure the deeply -AO that was perhaps even kore prominent in the monthly mean relative to the forecast.

 

 

Another unique flavor to this particular +TNH episode that was better foreseen in last fall's winter outlook was it's co-occurrence with predominately +PNA, which would ultimately bias the month in this fashion.

Emergence of Western CONUS Ridging Key In More Active Pattern

Guidance was originally insistent that the RNA pattern from the month of December would persist throughout the vast majority of the month of January, with the exception of a brief interval of PNA flex the second week of the month (10th-15th).

 

The above annotation ultimately proved correct in asserting that the forecast return of RNA after mid-month, as suggested by guidance, was in fact erroneous.

 

Eastern Mass Weather used history as a guide last fall in positing that the consistently negative PNA values from December would give way to a mean positive PNA in the mean during the month of January, as per the expected deviation from the cool ENSO oriented Maritime continent forcing.

December 2024-January 2025:

 

This notion was recently buttressed by data provided by Don Sutherland of Americanwx forums, which indicated that 10/10 -PNA streaks of 35 days or greater during the months of November-December since 1980, have averaged positive over the subsequent 30 day period.

 

Data Courtesy of Don Sutherland

It was posited that this represented an integral part of the forecast for the +TNH pattern that would become established during the latter half of January because the addition of a +PNA in this type of pattern would increase the likelihood of significant, and perhaps even major east coast storm, as opposed to the traditional overrunning type of precipitation events that typically rule these sort of regimes. This was evident last week, when the intense +PNA ridging was instrumental in the development of a major snowstorm across much of the northeast, despite the fact that southeast heights remained somewhat elevated.

 

The influence of the southeast heights were insufficient to preclude a major northeast snow event due to the influence of the western ridging in conjunction with the southward displaced PV, and western-biased negative NAO block acting to suppress the system enough to remain offshore. It was also suggested that the approach of the MJO to phase 7 at a relatively high amplitude It was also correctly anticipated that the trend for a more protracted period of PNA would constructively interfere and subsequently maintain a +PNA value for the duration of the month.

 

This particular convective forcing regime across the tropical Pacific indeed did indeed have this impact, despite what guidance at the time implied.

 

 

This is largely why the month ultimately ended up even wetter than forecast, despite the very dry first half.

 

 

 

Conclusions Regarding January

This behavior of the stratospheric vortex is precisely why it is very mild at the onset of these reflection events, during the antecedent Pacific trough pattern, but by ten days post reflection the pattern has reversed and is characteristic of an Alaskan ridge regime (bottom right above). Winter 2025-2026 represents a splendid illustration of why seasonal forecasting is a much more feasible endeavor when a proper diagnosis of the stratosphere is made given it's tendency to lead the configuration of the pattern on a hemispheric scale. Accordingly, it was posited just beyond mid-month that the general public was poised to learn just how costly that January thaw would be, as not only were our heating costs going to rise precipitously for the balance of January, but there also existed the potential for heavy snows. This lesson is now complete, as the region is mired in the midst of a historic and downright brutal stretch of winter that was set in motion by a sequence of events over 30 miles above the earth's surface, in the stratosphere. Indeed, this lesson can be carried forward;  as not only can an exhaustive assessment of the QBO (stratosphere) overlaid on the solar cycle yield insight as to how a mild, seemingly innocuous mid-month pattern can trigger a relentlessly punishing onslaught of winter. It was also elucidated how the current +TNH pattern punishing the eastern US is simultaneously planting the seeds to destruction for the polar vortex in February.

February 2026 Preview

Nuances Of Polar Domain Dictate Cold, Active Month On Tap

Here is the February segment of the forecast issued in last fall's winter outlook:

February 2026 Outlook

February Analogs: 2025, 2022, 2018, 2014,2008, 2002, 2001, 1971

 

The Alaskan ridge will rule this month at least to start, along with -PNA and +NAO. Some -NAO blocking could develop late if stratospheric warming gets underway early enough, but it likely holds off.

 

Alaskan Ridge Regime Courtesy Lee et al (2019)

 

 

 

The polar vortex should begin the month fairly strong, but will be weakening rapidly, as a SSW is likely by mid-month.  The January-February 2001 transition from reflection event to SSW may be a reasonable expectation, in terms of progression, as RNA pattern resumes and refocuses the cold west prior to any SSW. 

 

The interior will continue to be favored for snowfall as the storm track remains either inland or  hugs the coast. While not prohibitively warm, this will largely canonical La Niña month with  average to below average snowfall on the coastal plane, and average to above average snowfall across the interior.  Should the SSW develop in the earlier portion of the 1/17 to 2/17 window, the the second half of the month may change that due to the development of high latitude blocking, however, it is more likely not to occur until mid-month, as previously alluded to. The month will finish between +1F and +3F over New England and +2F to +4F over the mid Atlantic. 

 

Potentially Colder Than Forecast Month

 

The largest threat to this overall assessment is a colder threat, due to a continued uncoupling of the troposphere from a strong stratospheric PV. 

 

This is why the -NAO was so much more prevalent during the month of January than forecast, which caused the month to verify colder in the mean, despite an otherwise accurate forecast. However, this variation did not materialize until the latter portion of January, specifically during the +TNH interval, so this has the potential to bias the month of February even colder relative to forecast than January should this persist as appears as though it may.

 

Note how large of a role this could potentially play in the month verifying colder than the forecast composite per the latest guidance, initialized very recently on January 25th.

 

Although the mean of all seasonal guidance is much more congruent with the forecast composite, the January 1 initialization of this seasonal data is unlikely to have incorporated the ongoing -NAO blocking, so it is also likely be in error for the precisely same reason.

 

This colder pattern may very well yield an active month in terms of snowfall across much of the northeast considering that the busy northern stream portrayed in the analog composite from the winter outlook does seem to maintain support from latest guidance.

 

In fact, a busy start to the month is already explicitly implied.

This is crucial because there is little doubt on the part of Eastern Mass Weather that the aforementioned colder risk to the forecast is very real given the expectation that the NAO is likely to remain negative for the vast majority of the first half of the month, although there is likely to a +NAO interval during the middle third of February. This is due in large part to the continued expectation of a major polar vortex disruption by way of a split, and this is a conclusion that is only growing in confidence.

Imminent Polar Vortex Split To Protract NAO Blocking

The inference from the winter outlook last fall was that the easterly QBO would constructively interfere with the tendency for the modest, eastern biased La Niña to predispose the PV to major disruption(s) given that solar geomagnetic peak, which provides the most resistance to PV disruptions, will not be reached until roughly this summer. 

 

 

The Holton-Tan relationship, which dictates that an easterly QBO is correlated with both a greater incidence of, and an earlier development of SSW, reaffirms this conclusion when considering the solar cycle. In some cases, when the QBO and solar cycle are in conflict, they can either over ride one another or even cancel each other out (Gray et al 2004). Here is a list of combinations and the theorized relationships for clarity.

Solar min/W QBO: This is entirely consistent with the Holton-Tan relationship in that the westerly QBO essentially "wins". The PV is likely to be stronger than average until the final warming in spring.

Solar max/W QBO: In this case, the Holton-Tan relationship is applicable early on in the season, as major warmings are unlikely. However, the Holton-Tan relationship reverses mid winter and the latter portion of the season from February onward is susceptible to warmings and major PV disruption. Winter 2024-2025 was a textbook example of this.

Solar Min/E QBO: There are no inconsistencies here, as the entire season is more prone to polar vortex disruptions and SSW as per the Holton-Tan relationship.

Solar Max/E QBO (2025-2026): The Holton-Tan relationship applies early on given that PV disruptions are likely in December, before the relationship reverses and they are less likely later in the season. The final warming is of course the exception to this rule, while it is usually more relevant for spring, it can and does sometimes occur early enough to have an impact for the major population centers in terms of late season cold and/or snowfall.

Below are a couple of annotations to aide in the simplification and visualization of these relationships.

 

Interestingly enough, although statistically speaking early and late season disruptions are favored, there is a an outlier set of major PV disruptions noted in the solar max/E QBO quadrant of the chart above. This also becomes a theme when comparing the solar and QBO analog composites. 

Here is a list of cool ENSO/ solar analogs for the winter 2025-2026 season.

 

Here is a DM composite of these seasons.

 

There are obvious similarities between the Solar composite (right) and the QBO composite (left) given that they both feature high latitude blocking and poleward Aleutian ridging.

 

 

The primary difference is that the QBO analog composite is biased more towards early and late season NAO blocking, whereas the solar composite focuses the NAO blocking more in the early portion of the season.

 

 

The discrepancy is primarily with respect to late season owed to the aforementioned outlier set of mid winter PV disruptions, which is evident in the list of SSW analogs compiled from the solar and QBO composites, respectively.

January 17, 1971: PV Split

December 4, 1981: PV Displacement

February 11, 2001: PV Split

January 2, 2002: PV Displacement

February 22, 2008: PV Displacement

January 7, 2013: PV Split

February 12, 2018: PV Split

March 20, 2025: PV Displacement

 

The majority of the SSW events are split between the mid winter months of January and February, with three events per month. There is also an outlier event in December,1981, which proved a valid analog for the first SSW, and March 2025.  The primary analog events of January 17, 1971 and February 11, 2001 were both accompanied by PV splits and are the only two members to appear in both of the QBO and solar analog composites. The primary analog event of February 12, 2018 also ultimately culminated in a split of the PV, and is a member of the QBO and ENSO composite. This lends more credence to the mid winter outlier scenario that contains 6/8 the analogs. Thus the favored timeframe for a SSW and subsequent split of the polar vortex is during the January 17 to February 17 timeframe, with an increased emphasis on the latter portion of this window, which normally favors late season NAO blocking to commence roughly in early March. However, it is feasible that there may not be any lag time at all given that the antecedent conditions are consistent with both strong -AO/NAO, thus it may not need to propagate. The implication being that it may simply act to prolong the current blocking regime through the balance of February. 

Here is a look at latest guidance.

 

 

 

Note that the favored window is between February 10th and 17th, which is confident with the latter portion of the January 17th to February 17th window emphasized last fall. Although an official SSW via zonal wind reversal is not yet indicated, guidance is still likely adjusting, as both the behavior of the stratosphere , as well as the struggle that modeling would have with it were anticipated. The fact that a strong PV was modeled through February as recently as January 8th is illustrative of this.

 

In addition to the decided trends amongst current guidance, both the development of the forecast +TNH interval, as well as the recent behavior of the MJO also act to bolster confidence. 

Precursor Patterns Bolster Confidence in Major February PV Disruption

The recent high amplitude of the phase MJO wave in phase 7 was cited earlier as a harbinger of the +PNA interval that ensured earlier this month, despite guidance to the contrary. This behavior of the MJO is also predictive with respect to the stratosphere. According to recent research, amplified activity in the MJO in phase 7 has been linked to the occurrence of a SSW during the 12 days later (Garfinakel et al 2012). Garfinkel et al elucidate that "the MJO can affect the stratospheric polar vortex by modulating the vertical coupling of the mid-latitude planetary waves". 

 

Note that the modeled behavior of the MJO has it exiting phase 7 today, which corresponds to a SSW approximately February 9th, also with the the latter portion of the 1/17 to 2/17 timeframe and just one day prior to the window reflected on the previously referenced European ensemble plot. Furthermore, Baldwin er al 2020 found that there two precursor patterns that precede the wave absorption needed to trigger a SSW approximately 12 days later. it just so happens that the current +TNH pattern bares a an absolutely uncanny resemblance the wave 2 pattern identified by Baldwin, et al.

 

 

This would also imply a SSW on or around February 9th given that pattern remains in place. The operational European and GFS guidance support a split slightly earlier than this, by the 5th and 7th, respectively, thus it is prudent to assume that a SSW and accompanying split of the PV will ensue between February 5th and 17th.

 

This is likely will protract the high latitude blocking into at least the early portion of March. This implies an active fish to winter, however, this is conditional on the persistence of the blocking pattern within the polar domain because contrary to what some within the weather circles are intimating, the influence of La Niña is alive and well, albeit waning.

Extratropical Pacific To End Up Redolent Of Canonical La Nina

La Niña is undoubtedly weakening, as ENSO is climatologically predisposition to do at this juncture of the season. The lates weekly reading within region 3.4 is up to -0.3 as of January 24th. 

 

 

The ONI was a marginal -0.5 as of the OND tri-monthly reading and may very well fall below the La Niña threshold when the DJF value is released. This is evident by the infiltration of warmth within the ENSO subsurface.

 

However, there is a reason that the ONI value is calculated on a tri-monthly basis, as there is a lag due to the fact that there is no metaphorical "switch" in the atmosphere. It is a deliberate process for these changes to couple with the atmosphere and manifest throughout the hemisphere, especially given the perpetual state of cool ENSO that has been so prevalent of the better part of a decade.

 

This point is underscored by the fact that the Angular Atmospheric Momentum, which is a measure of the earth's circulation patterns, is modeled to remain indicative of La Niña into the month March.

 

Additionally, the -.92 RONI value as of the OND try-monthl period was still dropping and while that may be unlikely to continue, it does reaffirm that the fact that La Niña is still very evident when normalizing for climate change. The is supported by the fact that the MEI remained -0.8 as of the ND bi-monthly period, and while it is weakening, it is likely to remain in at least marginally indicative of La Niña through February. The point is that there is absolutely no indication that a decade's worth of angular momentum throughout the hemisphere is going to abate simply because the weekly value of region 3.4 is dropped below the -0.5 threshold. Why this concept is lost on so many skilled hobbyists and professionals alike is a question only those individuals can answer. That being said, here is a composite of the month of February for the weak La Niña dataset.

 

What is apparent is that the Pacific grows more hostile to winter enthusiasts, while the opportunity for high latitude blocking remains given the right circumstances, which seem to be in place this year as elucidated. Current guidance also is consistent with the development of a -PNA pattern, as the poleward Aleutian ridging wanes, as indicated last fall.

 

 

 

Needless to say, blocking within the polar domain will need to persist as is expected, or else an early spring may very well ensue. 

[40/70 Benchmark]

 

Ocean Storm Poised To Brush Region On Sunday-Sunday Night

Accumulations Largely Limited To Cape & Islands

It appeared on Monday as though the second major winter storm within a week may impact the area with heavy snows, however,  it now appears as though the region will be largely spared.

Synoptic Overview

The ingredients for major storm are still indeed brewing tonight.

 

The two systems are still expected to phase over the Tennessee Valley this weekend, which makes for an ominous set up if one were to take a cursory glance at the chart below.

 

However, as the weekend unfolds, two elements conspire to facilitate a track largely out to sea despite what is prototypically an ideal western CONUS ridge placement for a major northeast US strike.

 

First of all, there is a follow up "kicker" system dropping into the northern plains, which acts to force the lead storm to continue moving along before it can phase proficiently. This prevents the low from gaining as much latitude as it otherwise would have with a western ridge thought Idaho and Montana. Secondly, there is an area of lead convection well south of New England that works in conjunction with the aforementioned trailing kicker over the northern plains to bias the movement of the system on a more eastward trajectory than it otherwise would have given that western CONUS ridge position. Thus the system cannot gain enough latitude to have a major impact on the region. That being said, some significant snowfall cannot be ruled out over the cape and islands on Sunday afternoon into Sunday evening.

Expected Storm Evolution

Light snows will overspread the cape and islands around midday on Sunday, and quickly grow moderately moderate in intensity on Nantucket Island.

 

Snow may grow briefly heavy for a time on Nantucket Island, as snowfall grows more moderate over the rest of the cape. Light snow may develop back to the south shore of Boston with light accumulations. Windy conditions and some beach erosion are likely on cape cod and the islands, regardless of snowfall.

 

 

Precipitation then pulls back out to sea later in the evening and ends by midnight.

There could potentially be up to an inch or two of snowfall on the cape, islands and south shore, from a combination of the fringe of the storm and ocean effect snow.

 

[40/70 Benchmark]

 

First & Final Call for Wintry Saturday

Manageable Snowfall Amid Cold & Blustery Conditions

It may seem counterintuitive, but despite the fact that southern New England is going to be experiencing perhaps a plowable snowfall along with some pretty harsh winter conditions this weekend, the area is not going to be directly impacted by a major storm. It is true that one will in fact be forming, but as is often the case, the devil is in the details.

Synoptic Overview

A lobe of the polar vortex located in the vicinity of James Bay Canada has began interacting with a developing system off of the eastern seaboard this morning.

 

While the developing storm would normally be too far offshore to produce much in the way of measurable snowfall across the region, the nexus between the ocean low and the PV lobe will result in a bridge of energy in the atmosphere referred to as an "inverted trough", which will trigger a swath of light snow to break out across the area. 

 

 

The easterly flow around the invigorated ocean low offshore will represent another mechanism for snowfall, which will also ultimately act to enhance and even slow the incoming band in association with the inverted trough before it exists the coast. Precisely where this takes place will result in enhanced snowfall that could total up to several inches for a rather localized area.

Clear skies and dangerously cold wind chills will be left in the departing storm's wake on Super Bowl Sunday.

 

 

Expected Storm Evolution

The band of light snowfall associated with the inverted trough, representing a conduit of energy feeding in from the PV lobe to the offshore low will move into western New England by midnight tonight.

 

Simultaneously, ocean-effect bands will develop and feed into eastern areas.

 

The approach of the trough from the west will invigorate the ocean-effect bands during the pre-dawn hours of Saturday AM, which will cause the area to intensify and expand over the north shore.

 

The area of snowfall will likely bifurcate after dawn and into the mid morning hours, as one area in association with the parent trough persists to the west, as does the ocean enhanced snowfall to the east.

 

Here are the soundings from the hardest hit areas of Lawrence, Boston and Beverly, MA, which are indicative of nearly ideal, "cross-hair" signatures denoting moisture and max OMEGA (lift) colocated within the -12 to -18c.

This implies that although snowfall will not be extremely heavy, it will accumulate very efficiently since dendrites are likely to be nearly immaculate in structure.

The area of snow then congeals again during the afternoon before tapering off by evening.

There will be considerable blowing and drifting of whatever snow falls, as bitter cold, arctic air is drawn in on strong northwesterly winds around the departing ocean low.

 

 

First & Final Call:

Thereafter, the next chance for some modest storminess may come around mid week, next week. More on that later this weekend if the situation warrants.

 

 

 

 

 

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Saturday Snowfall Forecast Verification

Enhanced Areas Identified But Snowfall Under Forecast

Reality Versus Eastern Mass Weather Forecast Map

In order for a snowfall forecast to be truly elite, it is necessary to not only be highly accurate on a qualitative level (identify areas of heavier and lighter snowfall), but obviously it also needs to provide an accurate quantitative assessment of precisely how much snow will fall. When comparing the forecast to reality yesterday, it is apparent that the forecast was very accurate in the diagnosing which areas would be heavily impacted, while leaving much to be desired in that it greatly underestimated the snowfall in said areas.

 

Dual Areas of Focus For Enhanced Snowfall

The forecast on Friday identified one area of heavier snowfall associated with an inverted trough over central areas of the forecast area, and another zone of ocean-enhanced snowfall along the north and south shores of the Boston area.  The placement of these areas nearly perfect, however, amounts were more on the order of 8-12"+ as opposed to the 3-6"+ that was denoted. Granted this was a very difficult forecast, that is a rather large discrepancy that had major implications for those impacted.

Final Grade: B-

 

[40/70 Benchmark]

 

Messy Tuesday Evening On Tap

Light Snowfall likely Tuesday Evening

It will likely be a race against time as snowfall encroaches on the area during the Tuesday PM commute, however, the majority of the region should barely escape. The latter portion of the commute could be somewhat problematic across especially the western half of regions over the northern Berkshires and northern half of Worcester county. This is due to a rather modest weather system that will be "diving" east-southeast out Canada and across northern New England.

Synoptic Overview

This weak Northern stream disturbance known as an "Alberta Clipper" will be entering the Quebec province of Canada from Ontario tomorrow evening.

 

It will begin to intensify somewhat as is it does so overnight on Tuesday.

 

However, although it will be amplifying somewhat on approach, it will be passing to the north of the forecast area.

 

 

This will not only limit moisture influx, but will also introduce enough warm air to prompt precipitation type issues across the southern quadrant of the region, thus a light snowfall is expected.

Expected Storm Progression

Snowfall should begin to envelop the route 2 corridor around 6pm tomorrow, especially west of I 495, which will have some slightly impact not the latter portion of the evening commute so plan accordingly.

 

Snowfall will have mixed with and turned to rain near the south coast, cape and islands by the time the storm peaks around midnight tomorrow night.

 

 

The last of the rain should be clearing out by the AM commute on Wednesday. 

 

It would be prudent to still allow for extra time to the north of the Mass pike given the need for some snow removal.

First & Final Call:

 

 

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Close Call President's Day With Warm Up Thereafter

Major Storm Expected To Remain Largely At Sea

Expected Pacific Onslaught Likely Prohibitive

Eastern Mass Weather forecast the development of a fairly strong -PNA pattern for the month of February in the Eastern Mass Weather winter outlook issued last fall. This is precisely what has materialized and is forecast to persist throughout most of to the month by both the GFS and European ensemble suites.

 

 

This type of pattern often destructively interferes with major east coast cyclogenesis due the absence of a strong ridge over the western CONUS. It is evident in the graphic below that the energy crashing ashore in the Pacific Northwest has both flattened and displaced the ridge to the east. This prevents a direct strike from large ocean storm expected to make a relatively close pass to southern New England during the President's Day holiday, which does indeed have a history of major winter storms on the east coast.

 

 

Thus it is due to this anticipated shift in the pattern over the western CONUS that this system unlikely to earn a chapter in the annals of yore. However, some appreciable snowfall is likely if the northern stream disturbance is potent enough, so this bares watching. Additionally, anomalies due happen, so a larger impact from a more phased solution can not entirely be ruled out in the event that the ridge over the plains flattens enough to allow the southern wave to come up the coast. Thereafter, a thaw from the rather harsh winter pattern to date is likely in a similar progression that of January. 

MJO Led Winter Reprieve Likely Next Week

The MJO wave is rather diffuse at this time, however, there are growing indications that it will move into the MC and intensify beyond mid-month.

 

 

Here is the favored pattern based upon a reasonably robust MJO phase 8 response circa February 20th.

 

Note the resemblance to both mild mid-January Pacific trough regime.

 

 

And longer range ensemble guidance.
 

Although there exists fairly good agreement, the one discrepancy between the EPS (left) and GEFS (right) is that the former maintains more of a -NAO pattern, whereas the GFS guidance largely breaks it down. This lead to a milder pattern upwards of several degrees above average on the GEFS, as opposed to a pattern that simply moderates to near normal on the European suite. 

 

The reason for this discrepancy appears to the greater commitment of the GFS suite to amplification of the MJO as it approaches the MC later this month.

 

 

The colder European guidance is believed to be in error, and thus a warmer solution is favored for the balance of the month for four reasons.

 

1) +NAO is favored in the MJO phase 4 forecast composite posted earlier.

 

2) The feeble MJO wave depicted on the earlier referenced plot is actually inconsistent with the model's own Hovmoller diagram, which is in agreement with the GFS suite on amplification in phase 4.

 

 

3) The European guidance has been biased low in amplitude within the MC, which is why the bias corrected version of its' own output is also more in agreement with the GEFS.

 

 

4) Finally, the West Pacific warm pool remains alive and well, which predisposes the MJO towards the MC, as has been the case for the past several years.

 

 

 

Conclusions

The GFS scenario of MJO amplification in phase 4 leading to a mild pattern beyond mid-February is favored due to the demonstrated inability of the European guidance to properly resolve the predisposition of the MJO towards the MC as a byproduct of the formidable West Pacific Warm pool. This also renders its' modeled persistence of the -NAO later this month a less viable solution, which supports the milder scenario depicted by the GEFS. This means that a considerable thaw is likely beyond mid month, but what it does not mean is that winter is over. Although the anticipated SSW is not occurring as forecast, there are signs of additional weakening of the polar vortex later in the month that still may have an impact during the month of MARCH, in addition to any potential reconfigurations in the North Pacific pattern.

 

 

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Verification of Messy Tuesday Evening Forecast

Strong Effort

Here is the Eastern Mass Weather forecast issued on Monday valid for last night's minor event.

 

 

The forecast overall was very accurate, although there were a few amounts that narrowly exceeded the 1-3" range over the northern portion of the forecast, it was by a very small margin and they were few and far between. The outlier 6" report from Gloucester, MA is dismissed as being highly suspect. 

 

Final Grade: A

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More Active Week Ahead

Return of Pacific Trough Regime Implies Mixed Events

Mid January Redux Pattern Reprieve

The Eastern Mass Weather winter outlook from early last November posited that the milder Pacific trough regime would become prevalent during times of pattern relaxation.

 

 

The first interval of this pattern presented as forecast, during the middle third of the month of January

 

Another pattern relaxation of this ilk is also slated to return this week, during the middle portion of February. However, the trade-off for the milder temperatures will be a more active weather pattern in terms of bouts of precipitation.

Milder & More Active Pattern Ensues For Latter Half Of February

The implication for southern New England is likely to be a serious of attenuating waves that will be accompanied by light-to-moderate mixed precipitation throughout the region. The first such system is likely overnight Wednesday into early Thursday. 

 

 

The primary threat for a light snowfall is north of the Massachusetts turnpike.

 

 

Then a follow up system Friday night into Saturday, which may be more focused on Connecticut. 
 

 

The largest storm potential exists in association with a potential coastal development on Monday, February 23, however, the early indication is that this system is likely to pass predominately out to sea and pose a larger threat to the Canadien Maritimes.

 

 More updates throughout the week as needed, including the potential Tuesday issuance of a forecast for the Wednesday system.
 

 

 

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A Tale Of Three Disturbances

Wednesday & Friday Evenings As Appetizer To Potential Main Course on Sunday Night-Monday

While the precise evolution of the procession of storms poised to traverse the country this week still remains somewhat nebulous, the overall progression of the energy being ejected from the Pacific Trough discussed on Sunday is coming into somewhat better focus. As it now stands, there are three distinct pulses of energy that will be ejected into the plains to the south of the block located in the general vicinity of James Bay, Canada. The first two disturbances will be large eviscerated by the compressed height field between the block (north), and the southeast ridge (ridge) in their journey eastward. However, the last in this series of three disturbances has the greatest potential to amplify, since building heights over the western CONUS will allow the medium over the eastern US to relax.

Synoptic Overlay

The first piece of energy will eject out of the Pacific trough and into the upper plains on Wednesday, where is will amplify.

 

However, it rapidly begins to accentuate by the time it begins to impact the forecast area on Wednesday evening, as it encounters the compressed height field between the PV-James Bay block dyad to the north, and the elevated heights to the southwest owed to the deep, parent Pacific trough.

 

System # 2 then ejects into the plains at a slightly lower latitude on Friday, which allows it to maintain slightly more vigor as it translates eastward relative to the it's predecessor, that tracked immediately underneath the block.

 

This of course allows for the disturbance to maintain a bit more integrity as it approaches the area later on Friday and into the overnight period.

 

This should result in a light to perhaps moderate snowfall over the northern half of southern New England. What is also evident on Friday night is disturbance #3 entering the fray may by moving into the north plains.  The crucial difference here is that shortly after the system descends south of the Canadien border, ridging begins to build over the western COUNS intramountain region.

 

This allows ample room for amplification under the aforementioned PV-block dyad due to the fact that southeast heights decrease as a result of the building western CONUS ridge.

 

 

Note the decreased amplitude and further east position of the ridge in guidance from Sunday.

 

While this does in fact represent a more favorable ridge placement and intensity for major east coast storms, the fact that it remains marginal in conjunction with increased confluence to the north still implies that a major storm is dubious. There remains plenty of time to maintain vigilance with respect to this major storm potential to end the week, but in the mains time, there are also disturbances posted to impact the region on Wednesday and Friday evenings. 

Expected Evolution of Disturbance #1

Light precipitation should break out over the southwestern third of the region around midday tomorrow.

 

Most rainfall or mixed precipitation should rapidly transition to snowfall as the precipitation grows somewhat steadier throughout the afternoon, and potentially moderate for a brief window of time over a narrow corridor. 

 

Precipitation should then begin to taper off rapidly after midnight early Thursday AM.

 

 

First & Final Call for Wednesday Evening

Next up is the system slated to impact the region on Friday night.

Expected Evolution For Disturbance #2

Given that the parent mid level low pressure area will pass to the north of the area, this system will bring a mixed back of precipitation to the area due to southwest flow aloft.

 

Light snowfall will break out across the western third of the region to the north of approximately I-84 during the midday hours on Friday, with rain likely points south of there. 

 

 

This area of transition should progress to the vicinity of the Mass pike by the early evening hours, as precipitation grows more moderate in intensity.

 

Precipitation will then begin to taper off from west to east during the mid evening hours, and throughout eastern sections by shortly after midnight.

 

 

Any residual precipitation should be ending by dawn on Saturday.

 

 

Stay tuned for more a final look at the Friday potential on Thursday, and an update on the weekend potential if necessary on Friday.

First Call For Friday Night

 

 

 

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Final Call for Friday-Saturday Mess

Mixed Bag Likely Across The Region

A storm system streaking east-northeast from the plains will impact the area beginning on Friday and into at least the early portion of Saturday. Whereas vast majority of storms this season have featured primarily snowfall given the persistently cold temperatures, the track of this system is likely to complicate the forecast concerning precipitation type across the region.

 Synoptic Overview

The next system slated to affect the region ejects from the Pacific trough out into the plains by early on Friday.

 

It begins to weaken as it approaches the northeast due to the sharing influence of the compressed height field between the polar vortex/Hudson Bay block dyad to the north, and the increasing southeastern heights in response to the parent trough out west.

 

As the system continues to weaken, it is eventually forced to redevelop off shore to the southeast as it encounters the confluence flow around the vortex in the vicinity of the Canadian Maritimes, which may act to prolong snowshoers and advect in colder air during the day on Saturday. 

 

 

Expected Storm Evolution:

Light rain will break out over southwest portions of Connecticut by the midday hour.

 

Mixed precipitation will overspeed the balance of the region throughout the afternoon, with snow/sleet being the predominate precipitation type roughly north of the Mass pike, and a sleet rain mixture points south.

 

While evaporative cooling may result in a brief period of snowfall over northern Connecticut, Rhode Island and southeastern Mass, accumulations should be very light as precipitation will rapidly transition to sleet and rain as the decaying mid level low triggers a southwesterly flow and warm advection aloft as it passes though central New England. A brief period of icing over the higher train is possible, however, this should not pose a serious hazard.

 

 

Accumulating snow should continue well into the evening north of the pike and especially route 2 into the mid portion of the evening, with primarily sleet between the pike and the I 84 and rainfall points south.

 

Precipitation will taper off across western New England by midnight with a mixed bag continuing east, as redevelopment begins to occur off of the coast.

 

 

While this redevelopment will occur too late to prevent the transition to sleet and rain that will prohibit a heavier  snowfall accumulation across the area, it will perhaps prolong nuisance snow showers during the day on Saturday, as colder air is drawn in on a northeast flow, from the vortex over the Canadian Maritimes.

 

 

While these snow showers should not result in much in the way of accumulation during the day on Saturday, some icy spots are possible where refreezing takes place due to colder air being advected in on northeast flow around the developing low offshore.

 

Final Call

First Call Issued Tuesday, February 17th

 

 

 

 

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Severe Winter Storm Imminent Sunday Evening Through Monday 

Widespread Closures Likely Monday-Tuesday 

Eastern Mass Weather Mea Culpa Concerning Impending Blizzard of 2026

Eastern Mass Weather confidently opined as recently as Tuesday that there would be no major winter storm impacting southern New England on Sunday into Monday. It is now patently obvious that this is the exact opposite of what is actually going to happen due to some crucial morphologies that have taken place.

Synoptic Overview

The amplified Pacific trough responsible for the significant thaw this week is in the process of breaking down as this passage is written, but not before it delivers a couple of parting gifts that will ultimately replenish all of the snow that has melted, and then some. There are two final parcels of energy that have ejected into the plains from this dying trough during the day on Friday.

 

 

The amplification of the nascent ridge in place of the trough over the inter mountain west on Saturday will ensure that these pockets of energy encounter a relaxed gradient on the east coast over the weekend, as heights over the southeast fall in response to the development of the aforementioned ridge out west. 

 

 

This ensures that the energy is not sheared apart in much by the compressed flow between the polar vortex/block dyad to the north, and the southeast ridge to the south, in much same manner the previous two systems. It is because of this relaxed flow that the energy with these two disturbances can coalesce and phase beneath the block upon reaching the east coast by Sunday night.

 

This is where it becomes apparent that the North American landscape has changed since this major storm was expected to remain south of the forecast area. Not only has the PNA ridge over the western CONUS trended significantly westward into a position ideal to foster the development of major east coast winter storms, but the system currently affecting the region also departs into the Canadien Maritimes at a slightly faster pace, which allows confluence to lift north.

 

This is crucial because it the position of the PNA ridge and the confluence north of Maine that were cited  as the reasons why this storm would not be unable to travel up the coast. Below is a juxtaposition of guidance from Tuesday morning (right) and Friday morning (left) to better illustrate these changes.

 

 

The differences are apparent, and the discrepancy concerning the placement of the Western ridge is even more apparent when comparing guidance this morning (left) to last Sunday (right).

 

 

It is these changes that leaves the forecast area, along with much of the east coast, poised to experience the full wreath of the impending blizzard of 2026.

 

 

Expected Blizzard Evolution

Snowfall should overspread the region from south-southwest to north-northeast on Sunday afternoon.

 

Snowfall will rapidly become heavy Sunday night, with banding increasing at the apex of the storm from around midnight through Monday morning. Note two distinct bands, one over southeastern Mass and one from southeastern New Hampshire into the east slopes of the Monadnocks and Worcester hills.

 

 

However, it is important to note that these are estimates and the precise location of these bands

 is exceptionally difficult to diagnose. The very heaviest amounts of snowfall are likely to be within these bands, as well as on the east slopes of the Worcester hills, where a deep layer easterly fetch will induce upslope enhancement. 

 

While 850mb flow off of the Atlantic will ensure that the variation in snowfall between bands will not be as extreme as is often the case in systems of this magnitude, amounts are likely to be somewhat lower between these bands due to some extended residence time.

 

Some mixing is likely on Cape Cod during the height of the storm on Monday morning, as the track of the low comes close enough to entrain some milder ocean air on hurricane force wind gusts that will induce moderate coastal flooding and beach erosion.

 

 

Finally, precipitation begins to taper off later in the afternoon and into the evening, ending well before midnight Monday night.

 

First Call:

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Well Forecast Friday-Saturday Mess

Storm Goes According To Plan

The forecast for the mixed bag of precipitation that traversed the area last night and today was highly accurate.

 

There were very few surprises here, as mid level warmth allowed for mixing to the south of the Mass pike, which limited accumulations in these locales. However, further to the north, beyond route 2 and near the borders of New Hampshire and Vermont, respectively, precipitation remains all snow and several inches accumulated.

Final Grade: A

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Final Call: Severe Winter Storm Imminent This Evening Through Monday 

Widespread Closures Likely Monday-Tuesday 

Synoptic Overview

A ridge has rapidly built over the inter mountain west during the day on Saturday and will ensure that two pockets of Pacific energy encounter a relaxed gradient on the east coast over the weekend, as heights over the southeast fall in response to the development of the aforementioned ridge out west.

 

 

This represents a very favorable pattern for major storm development because the reduced gradient ensures that the energy is not sheared apart by the compressed flow between the polar vortex/block dyad to the north, and the southeast ridge to the south, in much same manner the previous two systems. It is because of this relaxed flow that the energy with these two disturbances can coalesce and phase beneath the block upon reaching the east coast by Sunday night.

 

This is where it becomes apparent that the North American landscape has changed since this major storm was expected to remain south of the forecast area. Not only has the PNA ridge over the western CONUS trended significantly westward into a position ideal to foster the development of major east coast winter storms, but the system currently affecting the region also departs into the Canadien Maritimes at a slightly faster pace, which allows confluence to lift north.

 

This is crucial because it the position of the PNA ridge and the confluence north of Maine that were cited  as the reasons why this storm would not be unable to travel up the coast. Below is a juxtaposition of guidance from Tuesday morning (right) and Friday morning (left) to better illustrate these changes.

 

 

The differences are apparent, and the discrepancy concerning the placement of the Western ridge is even more apparent when comparing guidance this morning (left) to last Sunday (right).

 

 

It is these changes that leaves the forecast area, along with much of the east coast, poised to experience the full wrath of the impending blizzard of 2026.

 

 

Expected Evolution Of Blizzard of '26

Snowfall should begin to work into the southwestern portion of Connecticut by around midday today.

 

Snowfall should then work up to about the Mass pike by 10pm, and will rapidly become heavy Sunday evening south of about I 84 in Connecticut, as well as throughout Rhode Island and southeastern Massachusetts.

 

 

Snow will spread into the remainder of the region by midnight, while areas of enhancement begin to take shape as the storm quickly ramps up. Note two distinct bands, one over southeastern Mass and one from southeastern New Hampshire into the east slopes of the Monadnocks and Worcester hills.

 

 

 

 

 

 

 

These bands will also be augmented by an ample influx of moisture at the 850mb level, which will act to limit subsidence between the banding with the exception of the Connecticut river valley, and to a lesser extent, the western slopes of the Worcester hills and Berkshires, as these locales will experience a down sloping phenomenon that will limit snowfall somewhat.

 

 

 

This is the portion of the storm on Monday morning that will feature blizzard conditions, as hurricane force wind gusts on cape cod induce moderate coastal flooding and beach erosion, as well as severe blowing an drifting of snow that will greatly impede cleanup efforts.

 

 

 

It is as at this point, during the height of the storm from roughly dawn through mid-morning, that banding is likely to stagnate for an interval of time, creating considerable variation in snowfall across the region. Thus it is the precise placement of these bands, which is exceptionally difficult to diagnose, absolutely crucial to the snowfall forecast. Here is an assortment of the approximation of the band based upon the 700mb temperatures profile of several models.

 

Note that the guidance on the top (NAM, EURO, EURO AI) are all reasonably similar with the placement of the H700mb warm front through the central portion of the forecast area. The likely axis of the deformation snows denoted with a line is directly on the poleward side of said front and it is here where the most intense snowfall rates are likely to occur during the peak of the blizzard on Monday morning into the mid day hours. The bottom two models, which are the GFS on the left and GEM on the right, are outliers with their placement over southeastern sections of Massachusetts and are disregarded. Here is the Eastern Mass Weather's best approximation of this band during the day on Monday.

 

The very heaviest amounts of snowfall are likely to be within these bands, as well as on the east slopes of the Worcester hills, where a deep layer easterly fetch will induce upslope enhancement. 

While 850mb flow off of the Atlantic will ensure that the variation in snowfall between bands will not be as extreme as is often the case in systems of this magnitude, amounts are likely to be somewhat lower between these bands due to some extended residence time. Snowfall will finally begin to taper off during the afternoon on Monday. Some mixing with rain occurs over the outer cape and islands at the height of the storm due to the fact that the track of the low is anticipated to come close enough to entrain some milder ocean air on hurricane force wind gusts.

 

Snow will be last to taper under the aforementioned bands, where the steadiest snowfall will tend to "rot", as the bands decay in place throughout Monday evening.

 

Final Call:

 

First Call Issued Friday Feb 20 @ 8pm:

 

 

 

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Forecast Verification For Blizzard Of 2026

Lessons Learned From The Great Storm & Forecaster Accountability

Cars Submerged By Record 41 Inch Snowfall In Fall River, Mass

A Record Final Snowfall Total of 37.9" Was Recorded In Providence, Rhode Island With Upwards of 43" In Tiverton

 The Eastern Mass Weather identified the March 1-15 period as a favorable period for a major, KU-caliber snowstorm along the east coast in the Winter Outlook issued early last November, as it turns out, history made an appearance six days early. The Eastern Mass Weather Final Call for the recent Blizzard of 2026 was good quantitatively speaking, as 30" or greater snowfall totals were actually anticipated dating back to First Call on Friday. However, as is evident in the final forecast verification posted below, these extremely heavy, all-time record-breaking bands of heavy snowfall ended up materializing south of forecast.

 

 

 

The forecast clearly left something to be desired as far as the mesoscale diagnostics of the best deformation banding and there are two primary reasons why.

Forecast Neglected Consideration Of Northerly Dry Air Drain

Confluence in association with the block over southeastern Canada was part of the reason why Eastern Mass Weather was originally pessimistic one week ago about the prospects of the historic storm making it far enough north to have a major impact on the majority of the forecast area. Although it became evident by Friday that said confluence would indeed retreat enough to allow the blizzard to move up the coast, there was ultimately not enough consideration given to the fact dry air remained perilously close to being entrained into the northern half to the region as the storm materialized.

 

 

This of course proved to be a major player in eventuality of a large portion of southern New England avoiding the truly crippling snowfall that was observed over much of southeastern Mass and Rhode Island. 

 

This negated the forecast rationale of a deep, 850mb layer easterly fetch off of the Atlantic mitigating subsidence zones between bands, resulting in the extension of historic snowfall totals to the eastern slopes of the Worcester hill, Monadnocks and Berkshires. Instead, the dry air was entrained from north, as the system congealed south of New England, and aided in relegating historic snowfall to one prominent deformation band to the southeast. Another forecast rationale was that there would be a secondary band of very heavy snowfall to the north west. Obviously one factor that prevented this secondary area of very heavy snowfall to the northwest was the aforementioned dry air intrusion, but there was also peculiarity in the frontogenic forcing pattern as the blizzard it's explosive deepening phase on approach to the region.

Aligned Forcing Restricted Coverage Of Heaviest Snows

The term "Fontoegensis" simply refers to the development of an area of changing winds and/or temperatures in the atmosphere. This is the primary mechanism that drives intense precipitation rates in strong coastal systems such as Monday's blizzard. Ordinarily, at last during the developing stages, low pressure systems are tilted southeast to northwest, and thus so are the areas of frontogenesis, with the lower levels (850mb) begin further southeast and the mid level (700mb) further northwest. The forecast rationale for the historic snowfall over the interior was due to a combination of intense 700mb forcing to the northwest, and deep layer feta of moisture in the lower levels off of the Atlantic.

 

 

 

 

Obviously the latter factor was nullified due to the dry air entrainment from the northern stream energy, which also acted to limit the ability to any residual 700mb forcing inland to produce heavy snows. However, indiosyncracies of the blizzard's evolution also dictated that the mid level forcing quickly congealed with the lower level forcing to the southeast, potentially due to not only the system's Uber-fast bombogenesis rate of development, but also the aforementioned drier air to the northwest. Note the strong 700mb frontogeneic forcing along the middle Atlantic coast and into the trip-state area responsible for very heavy snows from Delaware coast up through the tri-state area on Sunday evening. 

 

This is the area that was expected to eventually produce very heavy snows over the interior on Monday morning. It did indeed lead to over a foot of snowfall throughout much of Connecticut late Sunday evening into the predawn hours of Monday.

 

However, this area rapidly began to weaken and redevelop southeast during the predawn hours on Monday, eventually congealing with lower level forcing over Cape Cod by dawn.
 

 

This resulted in one incredibly intense band of snowfall with rates up to 4" per hour that moved onshore and pivoted over southeastern Mass, central-southern Rhode Island and extreme eastern and southeastern Connecticut throughout Monday morning and into the midday hours.

 

 

Either side of that band there was a pronounced area of what is referred to as "subsidence", or sinking air due to the tremendous upward vertical motion going on in that one uber-intense band. The development of this single band displaced the historic snowfall to the south east, and the dry air to the north ate away at the northern extent of the amounts, which is reflected by the forecasting error.

 

 

This has some similarities to the January 2022 blizzard

 

The collapse of the northwestern 700mb band was virtually complete by midday on Monday.

 

 

Barely discernible from the primary area of subsidence just to the east, as a blizzard for the ages paralyzed locales over southeastern Mass and central-southern Rhode Island.

 

 

The extremely rapid rate of intensification working in conjunction with the encroachment of drier air from northern stream is responsible for the restriction of historic snows to one primary band displaced south and east relative to forecast. This dry air impingement and displacement of the band south and southeast are likely attributable to shift in the expected track of the story after the Final Call map was realized very early on Sunday.

Blizzard Tracking South Of Forecast Is No Excuse

There is tendency in the meteorological community to passive aggressively shirk responsibility for errant forecasts by arributing said error to "changing data" as opposed to forecaster error. Models change because they are imperfect. This is a 100% "loser's lament" aimed at a deflection of accountability because it is absolutely incumbent on the forecaster to not only anticipate future changes in data, but also use experience to inform discretion when guidance is in error to apply needed corrections. The fact of the matter is that amateur forecasters like myself are especially vulnerable to "changing data" because time is limited with a separate full-time job, four young children and a wife, thus it often impractical to wait until the day of the storm to issue a Final Call given the constraints of life. However, be that as it may, I knew that dry air lurked to the north. I also understood that the pattern was marginally favorable for a close enough approach to allow for a historic impact given my original stance that storm would primarily pass out-to-sea. The fact of the matter is that the storm was projected to pass narrowly inside of the 40/70 Benchmark when the final forecast was issued.

 

 

However, the track shifted to the southeast by approximately 75 miles to a position outside of the benchmark in the 24 hours leading up the event, which is likely connected to the dry air encroachment to the north.

 

Some forecasters would offer the sentiment that "the forecast is only as good as the data", or "The forecast was bad because the data changed". This is utter nonsense because there is a reason that we have forecasters, and that reason is to detect and anticipate bad, or changing data. If the forecaster has enough data to issue a forecast, then they have enough data to be held accountable for said forecast, just as a pro athlete is considered healthy enough to perform if they are healthy enough to play. The public wants to hear about an injury the Monday morning after a bad game about as much as much as they want to hear about "changing data" after 3 feet of "Partly Sunny". The reality is that sometimes storms go-out-sea, but forecaster accountability should never suffer the same fate. Not for an amateur, and sure as hell not for any "professional".

Final Grade: D+

 

 

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Value Of Stratospheric & Solar Implications In Seasonal Forecasting On Full Display During Latter January-Early February

Sudden Stratospheric Warming Post +TNH Delayed But Not Denied

January Reflection Event Ends On Schedule

Near the end of January, Eastern Mass Weather reiterated the forecast from last fall, which called for the stratospheric reflection event responsible for the period of +TNH that played such a prominent role in the brutal stretch of winter throughout latter January, to conclude during the first half of February. This particular timetable was based on the following data:

"Note that the mean length of the process (reflection event) is  20 days, with 10 days being the minimum, and 60 days the maximum, per Lee et al (2019). The length of the 2001 (33 days) and 2018 (20) events were considered in the forecast for a reflection event to begin between approximately January 13th and 16th 2026, and end between about February 2 and 18th".  Judah Cohen, world renowned scientist for his research on the stratospheric polar vortex, confirmed that the reflection event did indeed commence in mid January, as forecast last fall.

"And as I have been routinely doing, looking at the wave diagnostics in Figure iv continues to display wave reflection over the weekend and into late January. For both periods shown, wave energy goes up and east over Asia, reflects off the stratospheric PV and then heads down and east over North America where the energy is re-absorbed and could potentially amplify the standing wave over North America and deliver cold air from the Arctic south, east of the Rockies. There is westward wave tilt with height over Asia and an eastward wave tilt with height over North America that is a classic signature of wave reflection. Though the eastward tilt is more pronounced in the first period compared to the second period".

The event concluded on roughly February 10th, consistent with the predicted date range of between February 2nd and 18th, which was derived from the 2001 and 2018 analogs.

 

However, by February 10th, it has completely dissipated and shifted to the Eurasian side of the hemisphere.

 

 

 

This corresponded quite well with the transition from +PNA to a -PNA regime, as expected, when the cold abated and shifted west.

 

Note how the cold was focused east during the +TNH/+PNA regime through February 10th. The cold was also anchored in place by the unexpected -AO/-NAO from latter January as a result of the stronger stratospheric PV decoupling from the troposphere.

 

Before shifting west following the end of the reflection event and onset of the RNA/+AO/+NAO regime on February 11th.

 

 

 

Although the cold shifted west, it was not as severe given the fact that the PV had retreated to Eurasia.

 

 

 

Thus although the +TNH has been entirely erased from the monthly mean, the negative height anomalies over the east have not as of the 21st.

 

The forecast for +1 to +3F monthly departures across the region will undoubtedly be too warm, due primarily to the unexpected early month -AO/NAO, as well as the inclusion of the very mild February 2018 and 2002 stratospheric analogs, which was a mistake. This was anticipated last month. The unanticipated high latitude blocking during the first half of the month in conjunction with the February 23rd Blizzard is at undoubtedly responsible for snowfall being concentrated closer to the coast than forecast this month. While the forecast will undoubtedly be too warm, the current -3 to -5F monthly departures across the region are likely to warm a bit more before month's end.

 

 

Although the composites for the month of February certainly left something to be desired, the diagnosis of the stratosphere as it pertains to the +TNH fueled severe winter pattern from latter January through early February was forecast with absolute surgical precision. This is due in large part to an exhaustive assessment of both the stratosphere and solar cycle in order to glean invaluable insight into the behavior of the polar domain during the winter season.

Stratosphere and Solar Implications Were Key

A list of QBO and solar analogs was constructed last August when devising a forecast for the polar domain for winter 2025-2026. Here was the list of 50MB QBO analogs as of last July:

 

July 2025 50MB QBO: -2.06 & descending

2021: 2.82 & descending

2017: 5.08 & descending

2012: -8.10 & descending

2007: -8.75 & descending

2005: -8.13 & descending

2000: 3.25 & descending

1974: -3.42 & descending

1970: -8.05 & descending

1962: -3.08 & descending

*Note that July 2014 was the third strongest match at .50 & descending.

 

July 2025 30MB QBO: -19.19 & descending

2021: -13.17 & descending

2017: -10.48 & descending

2012: -27.82 & descending

2007: -24.92 & descending

2005: -24.20 & descending

2000: -13.13 & descending

1974: -19.58 & descending

1970: -18.62 & descending

1962: -15.49 & peaking

*July 2014 was the strongest match at -19.29 & descending.

Here is an updated list as of October from the winter outlook:

 

October 2025 50MB QBO: -6.83 & descending

2021: 0.59 & descending

2017: 1.72 & descending

2012: -10.51 & descending

2007: -11.52 & descending

2005: -12.28 & descending

2000: 1.51 & descending

1974: -9.69 & descending

1970: -13.48 & peaking

1962: -5.32 & descending

*October 2014 was the third strongest match at -2.33 & descending.

 

January 2015 remains a very close match to January 2026 at the 50MB level:

January 2015 -9.95 & descending versus January 2026 -9.89 & descending 

 

 

October 2025 30MB QBO: -24.65 & descending

2021: -19.14 & descending

2017: -16.79 & descending

2012: -24.51 & ascending

2007: -29.05 & peaking

2005: -28.76 & descending

2000: -14.04 & peaking

1974: -23.12 & ascending

1970: -22.12 & descending

1962: -15.33 & peaking

October 2014 was the second strongest match at -23.86 & descending.

 

January 2015 remains a very close match to January 2026 at the 30MB level:

January 2015 -26.70 & descending versus January 2026 -25.52 & ascending

 

The 2014-2015 season was not included as an analog due to the fact it was a warm ENSO season, however, not only was it an elite QBO analog, but it was also a very strong solar analog.

 

This makes it a fine polar analog, and thus it is no secret why it was included in the +TNH composite used in the winter outlook last fall.

 

Here is the ground truth, which evinces how similarly the respective +TNH intervals from latter January through early February behaved.

 

 

It is not at all surprising that many southern New England sites have also endured their snowiest seasons since the 2014-2015 winter, as the similarities in the respective 500mb patterns during the January 20th through February 10th +TNH interval is evident.

 

This was to be expected given the Eastern Mass Weather polar analog composite from last fall.

 

Note how well it matched with a myriad of other different Eastern Mass Weather analog composites, all implying the same seasonal pattern in the mean for winter 2025-2026.

 

In conclusion, although the the winter of 2014-2015 was not deployed as a seasonal analog due to the fact that it was a rather poor ENSO match, it's value was evident upon a thorough analysis of the stratosphere and solar cycle last fall. Furthermore, it is this analysis that lends confidence to the fact that a Sudden Stratospheric Warming does indeed hang in the balance for winter 2025-2026, despite guidance remaining inconsistent.

Better Late Than Never: March 2026 preview

The January-February 2001 transition from reflection event to SSW was employed as an analog for the period in terms of the overall pattern progression, as RNA was anticipated to resume, thus refocusing the cold west prior to any SSW.

 

 

This worked out remarkably well, as depicted above, with the exception of the fact that the SSW event anticipated to materialize on February 13-14 never in fact took place. Eastern Mass Weather identified the January 14th through February 14th timeframe as being a favorable window for a Sudden Stratospheric Warming, complete with zonal wind reversal late last summer, which was amended to the January 17th to February 17th timeframe, with an emphasis on the latter portion, in the winter outlook last fall. Near the end of January this timeframe was honed even further to the February 13-14th period, which was supported by an emerging signal on guidance throughout the month.

 

 

Ultimately this signal failed to materialize, but it was deemed to be more of a delay, rather than a failure.

 

Recent guidance has reinforced this notion of a delay, rather than a denial. Note the near  unanimous consensus on a SSW-reversal as of February 24th, although the signal has waned somewhat since. This a trend that was also observed in the February failed attempt, so although a reversal and subsequent split of the PVcontinues to be favored, it is not a lock.

 

This is unlikely to be a final warming since the earliest on record is March 12, 1974, this March 6-7 would represent an unprecedented early final warming.

Whether or not this reversal actually takes places may be crucial to how the month of March ultimately evolves.

Warmer Risks For March

While it clear now that there will not in fact be a KU event during the higher risk window of March 1-15th identified last fall, the Great Blizzard of 2026 did occur on February 23rd, a mere six days before the onset of the early March window. Indeed, it appears that timing issues have plagued the forecast seasonal progression to some degree. Here is the forecast 500mb composite for the month of March that was devised last fall (left) versus the latest guidance (right).

 

 

Clearly these are polar (no pun intended) opposite patterns. This likely at last partially attributable to the stratospheric zonal wind reversal not taking place February 13-14 as forecast, which is why the month will verify warmer than the near normal to -2F forecast. This was a risk that was explicitly identified in the winter outlook early last November. This would have triggered the next round off high latitude blocking to take place by the end of the first week of the month, but since that did not take place, it will definitely take longer, which will in fact bias the month milder than anticipated. 

 

 

However, assuming that the SSW/reversal does indeed take place on March 6-7, as currently anticipated, this will should result in the return of high latitude blocking by third week of the month, or right around the spring equinox. While the month would still be biased warmer than forecast, it would likely end up colder than the exotically mild current guidance suggests. The resemblance between the latest forecast mean-March 500mb anomaly and the 500mb plot from the day that the SSW took place in the February 12th, 2018 analog is rather uncanny. 

 

This may potentially offer insight into they the timing of the February (forecast too warm) and March forecast too cold) forecast composites ultimately proved erroneous. This mild start to the month is confirmed by progression of tropical forcing.

Maritime Continent Forcing Heighten Warm-Risk

GFS guidance bolsters confidence in this warmer risk by depicting a slow progression and subsequent decay of the MJO wave through the MC phases of 4-6 throughout the first half of March.

 

 

MJO phases 4-5 teleconnect to the same mild, Pacific trough pattern observed during previous period of thawing this winter season.

 

 

This precisely what is currently modeled for the period.

 

A very similar pattern is denoted for phases 4-6 during the second week of the month.

 

Guidance evolving in like fashion with the mild Pacific trough regime maintained through the second week of the month.

 

 

The European suite essentially agrees, with an added twist.

Colder Risks Mid-Month

The European ostensibly supports the GFS, in fact even killing the MJO wave even sooner, in phase 4.

 

However, the MJO plot is often insufficient in that is cannot denote areas of duel forcing, which can be misleading. This is where the Homvoller diagram is invaluable, as it is able to convey a split wave. Not the emergence of a signal in the western Pacific towards mid-month, as the MC wave dissipates.

 

 

Both suites agree on the MC wave slowly decaying through the first half of the month of March, however, if the EURO is correct in modeling an emergence of the wave in the western Pacific at the same time that the potential March 6-7 SSW is manifesting in the polar domain, a very intriguing ending to winter 2025-2026 may be in store throughout the second half of March. Indeed, just as the stratospheric shenanigans and wintry potential of March has been delayed, so may be spring, ultimately.

 

Guidance currently displays more of a stretched PV with an absence of high latitude blocking, however, expect said pattern to emerge rather abruptly during the lead up to the period in question should the early month SSW materialize.

 

Finally, note the similarity to the 2018 analog with respect to early month MJO wave decaying in the MC.

 

 

March 2018 featured a major winter storm mid-month, which is something to remain mindful of in the haste to begin spring.