40/70 Benchmark

https://easternmassweather.blogspot.com/2026/02/latter-january-early-february-display.html

Hey, I'd still rather it split for verification purposes...better a few weeks late than never.

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.

February Review: https://easternmassweather.blogspot.com/2026/02/latter-january-early-february-display.html The unexpected early month blocking kept it colder than forecast in the east, but the midwest really torched and erased the early-month +TNH signature. Really tough to nail the pattern for the whole season, NVM the timing.

March Preview: https://easternmassweather.blogspot.com/2026/02/latter-january-early-february-display.html Looks bad for my preseason forecast right now, but I do thin there is eventually going to be some blocking that isn't being picked up get....the stratospheric zonal wind reversal being delayed has really thrown a wrench into my anticipated timing of the pattern progression...looks like mid March is the shot instead of early month.

How far did this actually track outside of the Benchmark?

I think it was the ENSO subsurface that I liked about 2012, if I recall correctly...

@WinterWolfYou remember when I mused to you last fall about how I almost included 2012-2013 as an analog, but didn't due to ENSO? Ha......there was indeed some value in that season after all. 2014-2015 was actually just about as perfect a QBO/solar analog as you will find....so the manner in which this season has unfolded isn't too surprising, even though I kind of gagged om the monthly composite this month. It's astounding how much you learn through the trial and error of actually doing this seasonals...can't teach that in a class.

My current spot was scooter for that...like 15 mi out.

I would have traded places.

40" can happen inland if you get under the banding long enough...NYS had in VD 2007....many areas in December 2020.

I mean, you still had 2 feet...even I wouldn't have bitched about that.

Tradeoff I am willing to make TBH...give me a decade of shit winters if we get an event like that.

Shit, he'll be whining in March, when I get a lousy, damn 7" SWFE that rains on him.

Well, tell CC I'm about due for my reach around.