40/70 Benchmark

Reminds me of 2022-2023.

Honestly, though.....A near record ACE seems to be the only way out of another torpedo DM period, and even then....maybe just servicable. 1998 was pretty active in terms of ACE and it still sucked. I imagine the ceiling could be something like a 2007-2008 outcome, where there is an ample reservoir of cold over eastern Canada via an elongated PV, but there is a sharp gradient due to a se ridge adjoining.

Just pick another death-knell for the northeast and play it safe-

That analog has been my early favorite. It will be nice to have a fall where I am not bickering with you every day

Well, I don't think AGW is why Arctic sea ice and SCE are not considered silver bullets of seasonal forecasting. As far as the run of crap winters, AGW has to be a factor, but the weather patterns have also just sucked for NE snow and cold...other parts of the globe and country have done fine. But no question that that the fact that we are seemingly haveing a "warmest winter on record" world wide each year is due to CC.

I think there is a much better shot of a more moderate La Nina than a positive PDO.

I would expect the PDO to be negative again, but we'll see.

While I think this is generally true, my work was more flawed than I implied here. Here is the post analysis. https://easternmassweather.blogspot.com/2024/05/winter-2023-2024-outlook-largely-failure.html

I agree in general, but I think we are a year or two off from peaking with respect to this. Here is my wrap up from last year. I was right about the forcing, but completely wrong about the implications of it....did not matter one bit. West Pacific drove the bus, which is why I think @bluewavenailed it with respect to articulating the disconnect between the ONI and RONI/MEI as reflective of "competing forces". And unfortunately for NE US snow lovers, all of the forces that competed with and overcame ENSO were in the west Pacific and were evil ones. https://easternmassweather.blogspot.com/2024/05/winter-2023-2024-outlook-largely-failure.html

Just saying....+NAO is most correlated with an increase in geomagnetic particles and solar wind, which peak in the few years following solar max. Regardless, I agree next winter looks mild again.

https://easternmassweather.blogspot.com/2024/05/winter-2023-2024-outlook-largely-failure.html

Winter 2023-2024 Outlook Largely A Failure A Case of Misinterpreted Implications of West Pacific Warmth Warmer than Expected December 2023 Using history as a guide, Eastern Mass Weather explained in the Winter Outlook why the convective forcing pattern in association with el Nino that had become established throughout the fall was unlikely to change during the winter. This ultimately proved correct. As forcing has remained anchored in the vicinity of region 4 on the western flank of El Niño, which coincides approximately with MJO phase 7. This represented a large portion of the rationale for expecting a fairly mild first month of meteorological winter. Note the resemblance between the composite for MJO phase 7 during an El Niño: The December composite of robust El Niño events per meteorologist Eric Webb: And the pattern across the North America throughout the Holiday period: However, the magnitude of the warmth during the month was much great than forecast. Here is the 500mb verification and associated temperature anomaly map for the month of December. Versus the December analog composite portraying the anticipated +1 to +3 forecast temp departures across the forecast area for the month of December. Clearly the December analog derived forecast was not warm enough, as many regional departures finished several degrees above average. Here is the precipitation forecast, which underestimated regional precipitation as another consequence of the intense Pacific jet: Versus reality: Overall the month was milder than anticipated in large part due to just how overwhelmingly prominent that Pacific jet remained in conjunction with a strongly positve NAO, as southern New England saw little to no snowfall regionwide. "While the month should finish slightly mild in the mean, it will be fairly active and should not be completely void of winter weather for the NE coastal plane, as there should be transient spasmodic PNA flexes. In fact, snowfall may very well be above average for the month across the deep interior and northern New England, where ski resorts should benefit from a blend of coastal storms and southwest flow events". But the devil is in the details with respect to the evolution of the hemispheric pattern and how it impacted temperatures across the CONUS. The AO averaged essentially neutral with a slight negative bias at -.22: The NAO, however, was decidedly positive at 1.94. The PNA actually averaged more robustly positive (1.94) than anticipated. Which belies the overall configuration of a Pacific basin that was poised to deliver a very mild flow of air throughout the central and eastern portion country for the majority of winter 2023-2024. Indeed, the pattern that emerged in December was indicative of a very pronounced positive phase of the West Pacific Oscillation, which is a cousin of the East Pacific Oscillation that is frequently referenced here on Eastern Mass Weather. Note the very pronounced strip of positive heights to the northwest of Hawaii during the month of December that were very characteristic of strongly positive Western Pacific Oscillation. The December H5 anomaly map above is fairly similar to the +WPO wintertime composite as it pertains to the aforementoned features. This should come as no suprise given that the month of December registered a a strongly positive WPO value of1.21 WPO value, which would become a reoccuring theme throughout the balance of winter 2023-2024. January Forecast a Modest Success Here is a review of the January forecast Narrative from November 11th: January 2024 Outlook January Analogs: 1958,1964,1966,1973,1978,1983,1987,1988,1992, 2010 (x2), 2015, 2016(x2) "This should largely be a tale of two months, as the warmer than average first half should give way to a colder second half that will be accompanied by the first of two historic seasonal snowfall potentials. The first half of the month should focus appreciable snowfall across the interior of southern New England, however, the coastal plane should join with a vengeance. A NESIS caliber storm is likely during the window between approximately January 22 and February 5, however, there is a possibility that it will be focused to the south of New England. The PNA should remain variable, which will continue to fuel an active pattern as the PV grows increasingly more disturbed in the wake of a SSW during the window from about Christmas through January 8. It would not be a surprise if precipitation was underestimated especially during the month of January in the analog composite, as the degree of warmth in the oceans should ensure plenty of moisture availability". Lets begin with a review of the behavior of the major teleconnections and an analysis of the forecast. The NAO was volatile and essentially neural for the month at +.21 The behavior of the AO can be characterized as very similar with volatile behavior that averaged essentially neutral in the aggregate (-.21). Thus the polar domain evolved largely as forecast. Finally, the PNA, while averaging slightly positive during the month of February at .45, belies the true nature of the pattern. First of all, the mid-month the arctic outbreak coincided with the one interlude of RNA, thus ensuring that the cold initially loaded west and only later translated east in a somewhat modified version. Additionally, the +PNA periods were largely biased to the west. This synoptic nuance was much like January 2023 in the sense that having the lower heights concentrated just off of the west coast actually reenforced deeper negative anomalies along the west in what was more representative to a RNA (-PNA) pattern. This is evident in the monthly H5 anomaly chart below. Note the ridge positioned off of the west coast, with the deep negative anomalies over the western CONUS in response. This is in comparison to the forecast H5 composite for the month January, which had slightly lower over the east than reality due to the Pacific ridge, presumably as a result of residual cool ENSO GLAAM and a very warm western Pacific. The result was that the month was slightly milder than forecast across the forecast region. Temperatures were expected to finish the month anywhere from near normal to about +2F over New England and near normal to as much as 2F below average over the mid Atlantic. However, New England finished more like +1 to +3F and the mid Atlantic near normal to +1F. This modest positive departure from forecast temp anomalies is in large part because of the mid month arctic outbreak loading west as a direct result of the aforementioned low Western CONUS heights. While this was a theme in the analog package, it was more pronounced than forecast. The forecast precipitation composite was heavily flawed, as January 2024 has been one of the wetter months of January on record along much of the east coast. But it was stipulated in the forecast that this was likely to be the case. "It would not be a surprise if precipitation was underestimated especially during the month of January in the analog composite, as the degree of warmth in the oceans should ensure plenty of moisture availability". And it indeed was an issue. This is likely due to an active sub tropical jet working in concert with a a great deal of mass flux, as evidenced by the volatility of the major teleconnections. Overall the narrative for the month of January was largely accurate. The snowfall distribution for the month was indeed heavily weighted towards the interior, as forecast, in large part due to the major storm that occurred January 6-7th. Additionally, there was in fact a major volar vortex disruption as forecast (SSW), however, it occurred 9 days outside of the specified 12/25-1/8 window, on January 17 per Judah Cohen. Although the first of two identified seasonal windows for a major east coast snow storm looks to pass unceremoniously (1/22-2/5), the period did not want for opportunity. The first threat, which technically occurred just prior to the onset of the period around January 20, was simply not afforded enough wave space for the follow up polar vortex lobe to amplify. However, the potential did not go unnoticed by CIPS, which flagged matches to the days leading up to the Great Blizzard of 1978 (a January & February analog) and the Blizzard of January 1996 (residual cool ENSO GLAAM) as viable synoptic analogs. And the second round of potential within this window is set to occur on around February 5th. Western Pacific Again Plays Key Role in Much Warm Than Forcecast February Here is the February 2024 forecast H5 composite: Which was reasonably well supported by guidance at the close of the month. But one key difference that is noted between the forecast charts above and what actually verified are the very low heights in the general vicinity of the Bering Sea that also showed up during the month of December. While the extreme +WPO had moderatred during January (.67) it was stronger than ever during February, registering a mean monthly value of 1.56. Much like the month of December, the February mean 500mb chart is indicative of a very pronounced positive phase of the West Pacific Oscillation. This is likely the primary reason why the the MJO spent much less time in phase 8 than forecast, which resulted in a much warmer northeastern CONUS than expected and significantly less high latitude blocking. The mean February AO value was .64 and the NAO value a strongly positive 1.09. Note the similarity between the +WPO loading map above with not only the previously posted February 2024 H5 chart, but also the pattern favored during phase 3 of the MJO during a warm ENSO month of February. This makes sense since the MJO is emerging in phase 3 after a very truncated passage through phase 8. Forecasts from Latter January were for the MJO to Spend Upwards of One Week in Phase 8 This was the proverbial "smoking gun" for the failed February forecast and the reason why the predicted range of normal to -2F February departures across the region verified so much warmer: Ended up more in the vicinity of the +4 to +5F range. Note the strong similarities to the +WPO loading pattern in terms of temperature anomalies during the DF period. The pattern did in fact turn cold with an opportunity for a major winter storm as advertised during the mid month flirtation with MJO phase 8, however, it only lasted one week due to the rapid translation of the MJO into the neutral circle. And once again the storm potential went unrealized. This is reflected by the drier than average monthly precipitation departure. This was not at all inconsistent with the precipitation anomaly forecast composite. 1991-2020: However, the very warm temperatures departures combined with the relative dearth of precipitation illustrated above to ensure much below average snowfall across most of the region. While the colder interlude of mid February was much shorter in duration and less remarkable than forecast, the warmer transition marked by a precipitous decline in the PNA near month's end was in accordance with the emergence of the MJO into the Maritime continent appears right on schedule. This acted to largely neutralize the monthly value at .09. Overall Very Mild & Nearly Snowless Month of March Well Forecast Here is the 500mb forecast composite for the month of March. Versus what has actually transpired. Overall a very solid 500mb forecast with a bit more blocking than expected over Greenland and Alaska. -.61 Mean AO for March & -.21 NAO The impact of the higher heights in the vicinity of Alaska as reflected by the modestly negative monthly EPO value of -.47 was to focus the warmest anomalies slightly further to the east than suggested in the forecast composite. Be that as it may, the higher end of forecast departure range of between 2-4F above average over the forecast area verified. While monthly precipitation was expected to be somewhat above average across the region: It verified well above average and ever more anomalous than anticipated likely at least in part due to the positive monthly PNA value of .45. While this was significantly more excessive than the forecast composite implied, it was congruent with the primary analog of March 2010. December-March 2022-2023 Composite Verification & Summarization Here is the DM 500mb anomaly forecast composite that was issued last November, as measured against the 1951-2010 climo period. Versus the actual DM 2023-2024 500mb anomaly chart. The general hemispheric configuration was portrayed with a reasonable degree of accuracy along with the expectation for a mild winter. However, these slight variances attributable to the west Pacific, as annotated below, were enough to ensure a historically warm winter as opposed to the mild season with more modest positive temperature departures that was predicted. This was very apparent when considering the DM temperature anomaly forecast composite measured against the 1951-2010 climo period. And the DM 2023-2024 observed temperature anomalies versus 1991-2020 climo. Finally, the precipitation anomalies were generally consistent with the forecast. However, the positive departures across the northeast were more extreme than anticipated, which is likely at least partially attributed to the record degree of warmth in both the ambient atmosphere and latent heat stored in the oceans around the globe. This may have played a role in the more extreme negative departures over the Ohio River basin, as well. Technical Discussion of Winter 2023-2024 The primary postulation of this past season's outlook was integrated into the title of "Winter '23-'23 Will Be A Lesson In Relativity". The implication of this was that there would continue to be a weaker expression of El Nino throughout the hemisphere relative to the robust ONI as a direct result of a more meager thermal gradient between the east and west Pacific SSTs attributable to the ongoing Western Pacific Warm Pool. This diminished SST gradient would lend itself to a weaker pressure dipole between the west and east Pacific. . ASO 2023 Pacific Pressure Anomalies Resulting in more subdued Westerly Wind Bursts. ASO 2023 Pacific Basin Zonal Wind Anomalies That are characteristic of a tamer and modified version of the Walker Cycle in which the gradients are muted by a warmer west Pacific basin in the wake of the recent prolonged stretch of cool ENSO amid an overall warmer climate. Typical Mature Warm ENSO Walker Cycle It was argued that a metric such as the ONI, which is entirely predicated upon SST, is ill equipped to detect that the Walker Cycle is out of sync with and thus inhibiting the growth of el Nino because this reality is masked by the fact that the entire Pacific basin is a sea of warmth. Thus the archaic ONI belies the true modest intensity of this el Nino, which is of insufficient capacity to fully alter the former cool ENSO regime. As a result, the convective forcing has continued to reside further west than would conventionally be expected, closer to the western PAC maritime continent. This despite the very high anomalies over the fairly small Eastern ENSO regions. This all proved correct, as the RONI reached an OND peak of 1.49 and the MEI maxed out at a ND peak of 1.1, both substantially weaker than the SST derived peak ONI NDJ value of 2.0. Additionally, the forcing during winter 2023-2024 was indeed pinned near the dateline in classic Modoki fashion. This is in fact displaced to the west relative to expectation considering this was a basin-wide event that failed to even translate as far to the west as modeled, as it it peaked with .3 on the El Niño Modoki Index as opposed to the forecast range of .6 to .8. However, the Eastern Mass Weather supposition that this westward displaced forcing and more meager expression of El Niño throughout the hemisphere would translate into a pattern favorable for more extended periods of colder weather and snowfall throughout the northeast than is typical of such a robust basin-wide event was incorrect. Although the seasonal forcing was very similar to that of the Modoki dataset as forecast, the resultant DM mean 500mb anomaly pattern was drastically different. Note how much more reminiscent the pattern this past season was of the eastern-based canonical data set, despite the westward extension of the SST anomaly pattern and especially the convective forcing. This is likely due to the very prevalent +WPO last winter. Which is also a common feature among the east-based composite, as the mean DM WPO value of that dataset is .40. Furthermore, 4/5 members of that composite featured a +WPO in the DM seasonal mean and 3/5 were decidedly positive at greater than .60. This particular extra tropical oscillation became a very prominent driver last season since it was biased so extreme in one direction (1.10 DM seasonal mean) and the influence of ENSO was partially negated by a warmer west Pacific basin in the wake of the recent prolonged stretch of cool ENSO amid an ever-warming climate. December-March 2022-2023 Teleconnection Forecast Verification Although the peak ONI of El Niño was slightly stronger than the anticipated range of 1.7 to 1.9, it was also significantly more east based than forecast (.3 EMI as opposed to -6 to .8 forecast range) and relatively weakly coupled with the atmosphere as a byproduct of the intense West Pacific warm pool acting to engage the influence of the warm ENSO event. This rendered the nearly ideal placement of the mean tropical convection less pervasive and allowed the West Pacific, which was configured in a manner that was very hostile for northeast US cold and snow, to be the most prominent hemispheric driver. This is likely at least partially why the polar domain featured less blocking than forecast, as both the AO (forecast biased .20 negative) and especially the NAO (forecast biased .66 negative) averaged significantly more positive than expected. As a result of the largely unfavorable polar domain as a potential consequence of a hostile West Pacific, the fact that the EPO region averaged slightly more negatively than expected (-.04 DM as opposed to .30-.60 DM forecast) was largely made irrelevant due to cold once again loading across the western CONUS, which has been a very prevalent trend over the past several seasons. There is a definitive tendency for -PDO warm ENSO seasons to feature a significant snowfall minimum throughout southern New England and the decision to not weight this more heavily into the forecast was rendered even more regrettable by underestimation of the strength of the DM negative PDO by .91. Ironically enough, the PNA forecast range of -.35 to -.65 erred by just about the same amount in the opposite direction, as the actual DM mean reading of .55 was biased negatively. However, this was rendered a moot point given the highly anomalous DM 1.10 WPO. Index Value Predicted '23-'24 DM Value Range Actual '23-'24 DM Value Forecast Error Pacific Decadal Oscillation (PDO) -.30 to -.60 -1.51 Biased .91 positive Perennial North American Pattern (PNA) -.35 to -.65 +.55 Biased .90 negative ENSO OND 1.7-1.9 ONI EMI: .6 - .8 (West Tilt Basin-Wide) NDJ 2.0 EMI: .30 .01 degree too cool and one month too early. Biased .30 West (J-M) East Pacific Oscillation (EPO) +.30 to +.60 -.04 Biased .34 positive Arctic Oscillation (AO) -.30 to -.60 -.10 Biased .20 negative North Atlantic Oscillation (NAO) +.10 to -.20 +.76 Biased .66 negative Below is the verification for ENSO, as well as the various teleconnections over the past several years Index Value Seasons Verified Mean Forecast Error Forecast Bias Pacific Decadal Oscillation (PDO) 0/8 Seasons .61 Biased Positive 5/8 Seasons Perennial North American Pattern (PNA) 1/8 Seasons .31 Biased Negative 4/8 Seasons ENSO 8/10 .002 too cold .35 EMI Biased cold 2/10 Seasons Biased west 3/6 Seasons (J-M) East Pacific Oscillation (EPO) 3/8 Seasons .36 Biased Positive 4/8 Seasons Arctic Oscillation (AO) 1/8 Seasons 1.00 Biased Negative 6/8 Seasons North Atlantic Oscillation (NAO) 1/8 Seasons .77 Biased Negative 6/8 Seasons The aforementioned relationship between -PDO warm ENSO events and a pronounced snowfall minimum in the vicinity of southern New England and the northern Mid Atlantic was indeed very pronounced this past season, as snowfall forecast errors were largest in these areas. December-March 2023-2024 Snowfall Outlook Verification City Predicted Snowfall Actual Forecast Error Boston, MA 42-52" 9.8" 328.6% NewYork, NY(Central Park) 25-35" 7.5" 233.3% Philadelphia, PA 27-37" 11.2" 141.1% Baltimore, MD 25-35" 11.3" 121.2% Washington, DC 20-30" 8.0" 150% Albany, NY 70-80" 31.8" 120.1% Hartford, CT 47-57" 24.6" 91.1% Providence, RI 30-40" 18.3" 63.9% Worcester, MA 75-85" 39.5" 90% Tolland, CT 65-75" 32.05" 102.8% Methuen, MA 65-75" 34.25" 90% Hyannis, MA 20-30" 8.5" 135.3% Burlington, VT 85-95" 60.8" 39.8% Portland, ME 65-75" 38" 71.1% Concord, NH 70-80" 55.5" 26.1% Snowfall was over forecast by as. much as 328.6% in Boston and 233.3% in Central Park. Errors were considerably less across interior southern New England, generally ranging from 90% to 102.8% and comparable to this over the mid Atlantic. The most accurate forecast was over the interior of northern New England, where very warm temperatures and a general dearth of high. latitude blocking were least prohibitive. Errors were as low as 39.8% in Burlington, VT and 26.1% in Concord, NH. How This Snowfall Forecast Compares To Past Efforts The mean snowfall forecasting error for the 2023-2024 winter season throughout the 15 select Mid Atlantic and northeast locations was 120.3%. This was the 7th most accurate forecast amongst the ten forecast seasons in terms of mean forecasting error. Only the 2022-2023 (900.6%) and 2019-2020 (678.3%) efforts fared worse. The seasonal forecast ranges verified in none of the cities and was closest in Concord, NH and Burlington, VT, with errors of 26.1% and 39.8%, respectively. The horrific results throughout southern New England and into the northern mid Atlantic region are the primary reason why this forecast struggled, where snowfall was over forecast by a ghastly 328.6% in Boston, MA and 233.3% in the Central Park station within New York City. The mean forecasting error with respect to the ten seasonal snowfall outlooks are as follows: 2023-2024: 120.3% 2022-2023: 900.6% 2021-2022: 36.2% 2020-2021: 14.1% 2019-2020: 678.3% 2018-2019: 90.3% 2017-2018: 13.2% 2016-2017: 35.3% 2015-2016: 71.4% 2014-2015: 10.9% The ten season running mean error: 197.1% 29/147 (19.7%) of snowfall outlooks have been under forecast. 91/147 (61.9%) of snowfall outlooks have been over forecast. 26/147 (17.7%) of snowfall outlooks have verified within the forecast range. Conclusions Last fall, Eastern Mass Weather correctly postulated that residual West Pacific warmth from the recent multi-year La Nina event working in concert with the background warming associated with climate change would yield a modified version of the Walker Cycle. This entailed that the Pacific basin pressure and thermal gradients that normally accompany and drive the development of the wind patterns (WWB) necessary to facilitate the transition of the Pacific basin from cool to warm ENSO were to a degree neutralized. The end result as expected was a more meager expressed El Niño than implied by the ONI, as well as a convective forcing scheme during this past winter that was displaced to the west to resemble that of a Modoki El Niño. While weaker El Nino events with Modoki like forcing are on average colder and snowier across the notheast, they also allow prominent extra tropical drivers to play a more crucial role in dictating the resultant weather pattern across the hemisphere, as "weaker" ENSO synonymous with competing forces around the hemisphere. Given that the 2023-2024 DM mean aggregate WPO value was 1.10 and one of the more extreme positive seasons on record, it is theorized that a played a very instrumental role in mitigating high latitude blocking and predisposing the southwestern US to troughing, which telconnects to higher heights over the northeast. This type of pattern is reminscent of the east-based canonical El Nino dataset and was reflecTed by the similarities that this past season had to that particular composite. Furthermore, there is a demonstrated proclivity for past El Niño events that have struggled to transition from a cool ENSO oriented Pacific basin, such as this past El Niño, to have the MJO struggle to enter phases 8 and 1. It is theorized that the vast pool of Western Pacific warmth amplified the tendency for the MJO to be predisposed to the Maritime Continent, largely eluding the dateline phases of 8 and 1 that are most favorable for northeast cold and snow, which is crucial during the warm ENSO climatological time for such occurrences during the month of February. In contrast, this is climatologically the most hostile time of the season for northeast cold and snow during cool ENSO events, so intuitively any struggle to transition the basin and eradicate residual cool ENSO GLAM in conjunction with a cold phase PDO that was significantly more robust that forecast would act to mitigate this most crucial period for northeast cold and snow during El Niño event. This tendency was indeed observed with respect to the MJO during the historically mild month of February 2024, which featured a notable absence of snowfall along the east coast. This was also noted during -PDO El Niño months of February 1995: And February 2007. However, February 2024 featured a much more notable absence of winter weather along the east coast than either of those months, likely due at least in part to the record amount of heat around the globe today as a byproduct of climate change working in concert with a much more hostile WPO. Moving forward, more consideration will be given to the West Pacific and the WPO will be added to future forecasting efforts. Additionally, greater caution will used with respect to the incorporation of older analogs into contemporary seasonal efforts amidst a rapidly warming planet. Final Grade for 2023-2024 Season: D

It's the few years after the solar max that is correlated with a stronger PV.

Yea, I like the late 90s cool ENSO period as an analog. Only good news out this way is that it can't really get much worse...we are pretty near rock bottom. Maybe a super nova ACE prevents another all out disaster for the NE.