40/70 Benchmark

Good.

We also have good patterns that don't have anything wrong with them and just fail to produce.

Right, but all I'm saying is that the pattern that people were excited about materialized for the most part. We got a huge NAO block and the PNA went positive. Details like the ridge being a bit too far to the west and the PV getting stuck out there are details you worry about closer in.

Pattern didn't suck at all. The resultant snowfall in our back yards did

I give it a D with 2" on the month...not an F because at least I got a coating the night before xmas eve and xmas didn't torch.

Agree.

I'm just laying naked under the Christmas tree...mistletoe toe directly over head and no one insight except for the KU book

Hey, I admitted yesterday it's a reach...but that is the luxury of not having your living depend on this stuff...you can have some fun and not be so close to the vest.

@Ji

A watch requires an adjustment?

Most storms fall somewhere along a Miller A/B hybrid continuum. All I meant in my blog is that I don't think they will close off in the GOM.

I ignored the EPS in my blog yesterday.

Ironically enough...there was a bit more blocking during December than I had expected, yet we ended up witha little less snow relative to my expectation near the coast. Strange month...

HECS watch this month.

Yea, I at least let New Year's pass...

Sit tight guys....its coming. Yesterday's update...

I'm hoping for some OES for my snow starved se MA brethren.

Just completely ignore.

Wolfie and I have been noting it, too...odd.

First time I have ever done this, but I ignored the EPS and went all GEFS. Its handled the Pacific better and is a better match for the shift in tropical forcing.

Yes. Don't need big cold.

Watch and wait....

@Sey-Mour SnowThinking about it more, this probably moves the window up a week from 1/13 to 1/27...but the outlook is what it is and is graded as such. But if I were revising it now, I would probably go 1/13 to 1/27.

December Largely Evolves as Forecast with Active January on Tap Changes afoot in the Pacific Herald Explosive January Potential December 2022 Review December Analogs: 1970, 1971, 1973, 1975, 1984,1992, 1996, 2005, 2007, 2008, 2013, 2016 Before delving into 2023, it is only appropriate to recap the final forecasting effort of 2022 given that the ball has yet to drop in Times Square. The season was forecast remarkably well with the notable exception being that the blocking within the polar domain was more prominent than anticipated, as the most anomalous episode was postulated to instead take place in January. However, as illustrated in the above annotation, clearly the massive episode of blocking materialized during the month of December. While this did not effect the forecast much for the primary area of focus, here in southern New England, it did mean a slightly cooler outcome relative to the expectation across the mid atlantic and southeast, with slightly warmer outcome than forecast across northern New England. December Temp Anomaly Forecast vs 1991-2020: Actual December Temp Anomalies Through 12/27: The stronger than anticipated high latitude blocking during the month of December is represented very clearly in the H5 anomaly plot: vs the composite December forecast and the more modest degree of high latitude blocking, which allowed for some southeast ridging and thus a slightly milder outcome in that region: What is also apparent in the composites above is that the Pacific largely behaved as anticipated with a predominately negative phase of the PNA, which favored cold loading to the west. Thus it is not too surprising that precipitation on the west coast was more prolific than the sensible weather composite had indicated for the month of December: Actual: Forecast Composite: This is very reminiscent of the -PNA style extra tropical Pacific pattern, which features 3/5 primary ENSO analog seasons in 1955-1956, 1970-1971 and 2010-2011, respectively. Be that as it may, while the national forecast was not perfect, the forecast narrative for the month of December favoring the deep interior and elevations, as well as northern New England for snowfall was generally correct. "The month will gradually turn colder as the high latitudes become more disturbed, and while the mid Atlantic may find snowfall scarce, New England should not...especially north and interior. However, coastal areas/lower terrain may have frequent precip type issues during coastal storms due warm SSTs. Some elevation events are certainly possible. There will also be southwest flow events/warm air advection events, which will be more fruitful for the coast in terms of snow. A white Christmas is likely across the interior and northern New England, and possible along coastal southern New England. It is very unlikely for at least the lower terrain of the mid Atlantic". Note that some changes are apparent with respect to the PNA over the course of the last week to ten days of December that may serve as an important harbinger of things to come as we enter the new year. Active January Pattern & Potential Deviation from La Nina Regime to Ensue Following Warm Start Although much of what was postulated regarding the month of January in the release of the Eastern Mass Weather Winter Outlook back in November still remains valid, there are some adjustments to be made in the closer range. Here is the January portion of the forecast from November as a refresher: "January Analogs:1971, 1976, 1985, 1986,1996 2011, 2014, 2021, 2022 January is like to be consistent with climatology in that it will be the most consistently fierce month in that there is likely to be "storms and rumor of storms", to quote an old and wise weather weenie. It was mentioned that opportunities for a coupling of EPO/PNA style blocking with NAO blocking would be scarce this season, but if it is to occur, it will be this month, as evidenced by the January 2023 forecast H5 composite: The recovery of the PNA from the RNA month of December is also evident in the ECMWF forecast: Note the opportunity for cross polar flow and what will at times be frigid conditions. This will also be a month of great flux, which will likely couple with well above average N hemispheric SSTs and a surplus of water vapor owed to the submarine eruption of Hunga Tonga last January help to facilitate a large scale and perhaps generation storm opportunity. This event will be the signature storm of the season, and will have the potential to cripple travel over a widespread area for a time in a window between approximately January 6th-20th This is the month that the mid Atlantic likely receives the bulk of its seasonal snowfall. January will be the inverse of December in that it will be biased more wintery earlier, but blocking should relinquish its grip and it should modify with flooding threats possible during a major thaw. January 2023 Forecast Temp Anomalies: 1951-2010: 1991-2020: January 2023 Forecast Precip Anomalies: 1951-2010: 1991-2020: It would not be a surprise if precipitation was underestimated especially during the month of January in the analog composites, but also even during the season in general given the unique circumstances surrounding Hunga Tonga". January Polar domain The primary deviation from initial iteration of the forecast back in November is that the anticipated thaw period is occurring during the first week of the month, as opposed to later in the month. This is due to December's midwestern blizzard phasing so far to the west given the PV lobe being trapped in western Canada, that it acted to bombard said block and hasten its demise, which has expedited the warm up. This is why coastal southern New England observed less snow during the month of December than implied in the outlook during and why the NAO trended positive later in the month, as opposed to lasting into early January as forecast. Not only does this most the thaw from the latter half of January to the first week of the new year, but it also renders an extreme amount of high latitude blocking during the month relatively unlikely, given that it would be quite anomalous for another round of blocking to first the first in such a rapid succession. However, it DOES NOT mean that the high latitudes will be hostile to sustained wintery weather across the area during the month of December because that is not at all appear to be the case. In fact, there are still some signs that high latitudes will be somewhat disturbed, as evidenced by guidance suggesting the Arctic Oscillation will trend strongly negative again: And the NAO perhaps modestly negative, but not at all exceedingly positive beyond New Year's week. There corroborates growing evidence that the polar vortex will continue to sustain some assaults and become somewhat elongated toward this side of the globe. This will not only sure at least seasonable cold after a very mild first week, but heighten the risk for lobes of the polar vortex to phase with Pacific shortwaves. This is especially given the occurrence of west coast ridging, and since here is reason to believe that there will be just that over the course of the month of January, there exists explosive east coast storm potential during this time frame. Guest Appearance by El Nino Looks Ominous in January It has always appeared as though the Pacific domain would undergo fairly dramatic changes from December to January, as perhaps a harbinger of the ENSO related passing of the guard to ensue over the course of the coming year. And while perhaps the ominous check from the polar domain may have been cashed a bit earlier than anticipated, but Pacific appears prime to deliver based upon latest tropical guidance. The are signs from both the European and GFS camp that the MJO looks to make another attempt at advancing into phase 8 as we approach mid January. And while previous attempts have failed due to the deconstructive interference pose by cool ENSO's proclivity to relegate tropical forcing to the marine continent, there are drastic, albeit not unanticipated changes taking place. Here is the forecast for the progression of tropical forcing over the course of the first half of January, courtesy of Mike Ventrice: Note the steady progression of the the tropical forcing, denotes by negative vertical velocities steadily progressing towards the dateline. This is the polar opposite of modoki la nina favored tropical forcing, which is the milder type of la nina regime that that favors forcing in the maritime continent and mild conditions on the east coast. Note the increased similarity relative to the east-based la nina composite, which favors more poleward Aleutian ridging. But perhaps most importantly is the closest match with respect to tropical forcing, which is that of the prototypical modoki el nino season of 2009-2010, granted with a less pronounced sub tropical jet. This pattern offers the most explosive east coast storm potential due to amplified west coast ridging. There are three caveats: 1) Despite residual surplus water vapor from Hunga Tonga, this is still a la nina season, granted with a steadily decreasing intensity and coupling to the atmosphere. Thus with somewhat less of a STJ presence than observed with an actual modoki el nino pattern, cyclogenesis will likely be more prone to Miller B bias relative that seasonal composite. 2) The previously referenced VP plot is MJO filtered, thus is assumes some level of successful MJO propagation as a baseline. However, event the unfiltered guidance is implying some level of dateline propagation of forcing. 3) What is relatively high confidence is periods of rather strong PNA style ridging during the month of January. However, said ridging may not be as prevalent in the vicinity of Alaska, which is why seasonal cold is more likely this month and any true arctic invasions may be relatively fleeting and/or offset by the mild onset of the month. This is evidenced by an East Pacific Oscillation that may be fairly neutral in the mean. Current long range guidance reflects the evolution of the changes in the Pacific quite well. From week one: Through mid month:

https://easternmassweather.blogspot.com/2022/12/december-largely-evolves-as-forecast.html