40/70 Benchmark

December recap and January preview... https://easternmassweather.blogspot.com/2023/12/very-mild-december-prompts-change-to.html

Very Mild December Prompts Change to Forecast Methodology; January Looks to be a Month in Flux Stratospheric Warming Likely Early in 2024 December 2023 Review: 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. Thus far in the throughout the month of December this has proven accurate. 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, there are two points that have become clear throughout the month of December. First of all, it has become apparent that the DM seasonal forecast composite inadequately conveys the anticipated monthly progression over the course of the winter season. This is due to the fact that during any given year, there may be several analogs that may progress differently, despite ending up fairly decent matches in the DM seasonal mean. It was very apparent this December. Here is the 500mb verification and associated temperature anomaly map for the month thus far through 12/26: Versus the DM mean composite for the month of December: Note how the December forecast composite derived from the DM mean seasonal composite fails to capture the deep vortex in the vicinity of Alaska, which drove the active Pacific jet that eradicated the cold air supply from the North American continent. However, the December analog composite does not miss this feature and also more accurately conveys the anticipated +1 to +3 forecast temp departures across the forecast area for the month of December. The second point is that the December analog derived forecast was still not warm enough, as many regional departures will finish several degrees above average. However, be that as it may, it is clear that the monthly analog derived composite provides a more precise representation than the DM mean seasonal progression and will thus be used moving forward. Here is the precipitation forecast, which underestimate 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, as southern New England saw little to no snowfall regionwide. But the rest of the teleconnections largely behaved as anticipated. "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". The AO averaged essentially neutral with a slight negative bias: The NAO neutral with a slight positive bias: And the PNA slightly positive, albeit variable: The predicted descent in the PNA may play a crucial role in modulating the rate of any pattern evolution as we head into the New Year. January Forecast Remains Consistent with Some Warmer Risks Early January still appears to grow more seasonable from the very mild December regime, as the Alaskan vortex finally begins to dislodge, however, the forecast decline of the PNA is reflective of the fact that said lower heights look to translate down the west coast. This evolution is consistent with the forecast position of tropical convection entering MJO phase 3. And if anything the correction vector is pointed warmer per Paul Roundy's extra tropical regression tool. Tropical convection is then forecast to reach into Maritime phase 4 by mid month. Ascent Increases Over Maritime Continent of Indonesia & Descent Develops Over Western Pacific by Mid January This is congruent with the anticipated mid month warm up described in the Eastern Mass Weather winter outlook. "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". And whether or not the impending early January stratospheric warming ultimately meets the technical definition of a SSW and triggers a reversal of the higher level winds from westerly to easterly per forecast remains up for debate. But Judah Cohen currently favors a SSW and subsequent split of the polar vortex. "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". Regardless, what is clear is that the polar vortex should ultimately remain increasingly disturbed as the month of January progresses. Thus the energy from said stratospheric warming should have completed its downward propagation into the troposphere around the same time that the MJO exits the Maritime continent by around approximately January 20th and beyond. It is at this point that the watch begins in earnest, as per the Eastern Mass Weather winter outlook progression. "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". This conceptualization is reinforced by research conducted by meteorologist Eric Webb. Until that time keep a close vigil on what promises to be a very volatile month replete with large scale flux and constant pattern evolution. Here are the forecast composites for review. January forecast H5: Versus current guidance: January Forecast Temperature Anomalies: Versus Current guidance: January Forecast Precipitation Anomalies:

Not much...mainly over the deep interior and NNE, which it did.

To a degree, yes...they already are.

Yea, I am not can kicking or back tracking....I posted in plain English that I had specified the second half of January as the real change, per back loaded el Nino climo....if that period can kicks, then I promise I will make some concessions.

If we get to 1/20 with no sign of imminent change, then yes...trouble. I think by mid January I knew I was screwed last year, though I still thought that March would produce.

My most valuable seasonal efforts are the ones that do NOT verify.

Models are enslaved by the physics....that is why its incumbent on the forecaster to utilize analogs and experience to know when to diverge on a seasonal level.

I feel like the difference is that we are adding sincere and empirical content the vast majority of the time....the ball busting is in the minority. Its just constant passive aggressive siege with them. And sure, my content supports my opinion, duh....but folks have seen be self critical and admit when I am wrong. If I need to do so again this season, then so be it...I will.

I think this was the most accurate portion of my December work There will be undoubtedly a great deal of unrest from the contingent of self-proclaimed weather experts on social media who remain traumatized from what seems like a multi-decadal run of cool ENSO events. And while some of that residual la Nina like atmospheric momentum will undoubtedly remain, rest assured that the wheels of change will be in motion by the new year. El Niño will continue its westward progression at the surface towards being better colocated with the central Pacific forcing as the polar stratosphere concurrently begins to warm. There Should be no repeat of January 2023.

That is the most passive aggressive "FU" "like" in history

Problem is how long does that continue? That isn't how it earned the moniker "Dr. No"..... We should see the processes that will change that at work next month.

The problem is they aren't vapid and mindless...they offer good insight, which is dangerous because they aren't using it to foster objectivity as they should. Instead, the aim is to passively aggressively elicit emotion from those invested in wintery pursuits and the quality of this place suffers for it because that is inimical to objectivity.

Any guesses how long it would take for @MJO812to be neutered via emoji if he were to post signs of change at week 4?? Any takers??

Oh, I know...just using your post as a launching pad, so to speak. Its convenient how some of these folks are pointing out how they see no sign of change at WEEK 4, as we have other posters drawing attention to the significant discontinuity at DAY 4 . Keep in mind how guidance is likely to play catch up following any major strat warming. The issue maintaining objectivity is two-fold: 1) We have frustrated weenies 2) We have trolls preying on said frustration.

I will probably end up too cold in January...my honest guess. But you tell me how this has aged from early November: 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.

I love how some folks exercise selective memory, too....no mention of the predicted SSW and ultimate high latitude blocking that culminated in a 3' snow event 50 miles away from Boston last March.

Sure, which I have pointed out...why is that relevant? I also said the same thing in 2014 and 2015...... You don't see why it will look different in week 4..great. Carry on.

I mean...you tell me. Balance of November-December 2023 Outlook December Analogs: 1953,1957,1965,1982,1986,1987,1991,1994,1997, 2002, 2004, 2006, 2014, 2018(x2)

I mean, its disappointing that December was warmer than expected and entirely devoid of snowfall, sure.....but its not a huge deal because I didn't expect a good month. And it doesn't change how I feel about latter January and February. No...not at all.

January is a month in a great deal of flux and the second half should be much more wintery.

This fits with the anticipated progression...I have always thought there would be another period of warmth after the early month cool down, while the any strat shenanigans propagate, so that makes sense to me...I think the MJO may also be going Maritime again.

They just mean a continuation of no snow in NE.

Totally. I have been pinned to a 1.7 to 1.9 peak ONI range since June.

Another one that Snowman must have missed lol He normally streamlines that guy's twitter feed via IV.