40/70 Benchmark

Yep, it's a concern.

I said before the season that the GFS has really improved.

@512high, I received your check for F5. Thanks....hopefully this Wednesday deal keeps trending favorably.

Nah, it was July

Early Season Winter Storm Possible Mid Week Early Season Winter Storm Possible Mid Week The Situation: There appears to be a take two on the early winter "lion" that failed to materialize last week. Clearly not all of the potential for mischief in the atmosphere is realized, otherwise the plant earth would be nearly inhabitable and only individuals such as your's truly would rejoice. However, there appears to be yet another, higher percentage opportunity for winter to fire the first significant shot across the bow of southern New England next week, as illustrated by the mass convergence evident in the major teleconnections of the both the pacific: And the arctic: While the overall pattern across the hemisphere is relatively hostile both with respect to the pacific and polar domains, the shape and orientation of the polar vortex is such that it allows periodic intrusions of polar air into the our sector of the western hemisphere. One such episode will occur on the heels of a very mild and blustery day on Monday. It is this system that will bring early week rainfall and scattered wind damage before propelling a strong cold front through the region overnight on Monday into early Tuesday morning. It is this polar airmass that will set the stage for what is likely to be region's first significant and widespread snowfall of the 2021-2022 winter season on Wednesday. The initial upper air shortwave over the Saint Lawrence river valley will initially induce a southwest flow aloft that will cause precipitation to break out during the day on Wednesday. However, as the system encounters the relatively stout antecedent polar airmass in place it will begin to transfer the energy to the coast. Since there is no high latitude blocking or west coast ridging in place to provide the impetus for this evolution to transpire as such, it is subject to the nuances of timing. Thus far, it appears as though the system will arrive while the antecedent airmass provides enough resistance to produce a winter storm, however, there is still about a day or so for that to change. Just how quickly said resistance induces a transfer of energy to the coast in order to end the southwest flow aloft will determine how much of the snowfall transitions to rain, sleet, ice and how much precipitation falls. More diffuse primary energy and more pervasive antecedent polar air will promote a faster transfer of energy and heavier snowfall totals across the region. However, if polar air provides less resistance and the primary energy persists for a longer duration, than the protracted southwest flow aloft will ultimately advect milder, and drier air into the region ensuring nothing more than a modest to moderate snowfall across the entirety of the region. Preliminary Anticipated Storm Evolution: The warm front in association with the first system driving far to the northwest should advance through the region on Monday warming, followed by rainfall and very gusty southwest winds with some sporadic damage and power outages. The region will spend Monday in the warm sector before the trailing cold front begins to advect colder air into the region overnight on Monday. The follow up disturbance will approach the area and induce an initial southwest flow aloft, which collide with the antecedent polar air mass in place to cause snow to break out from southwest to northeast on Wednesday morning. Precisely just how long the primary parent energy remains prominent will determine how extensive the period of southwesterly flow will last. It is likely that precipitation will mix with/change to sleet and rain inside of route 128 and near and to the south of the Mass pike. The Wednesday morning commute should be especially problematic across SW New England. However, the Wednesday evening commute should be a messy across the region, especially north and perhaps across northern Connecticut, as a significant period of glaze is possible. While some freezing rain is also possible outside of I 495 and south of the Mass pike, it should be most prevalent across the northern section of Connecticut, where the southwest flow aloft is likely to persist the longest and is able to thin the layer cold sufficiently in the mid levels of the atmosphere. Regardless of what exactly transpires, the system looks to exit the area early Thursday. First Call: The primary question to ponder over the weekend and into early next week is just how fast that coastal energy transfers and consolidates off of the coast. The 12z GFS is very aggressive in closing off the coastal low in the mid levels late Wednesday night. H85: H700: This has important implications on the forecast because it shifts winds in the mid levels of the atmosphere from south and southwesterly: to more easterly, which limits precipitation type issues both in duration and extent by and duration. This also acts to protract the period of accumulating snowfall overnight Wednesday into early Thursday, especially across the northern and eastern third of the region. This cold have significant implications on the Thursday morning commute. Hopefully there will be more a consensus with respect to the evolution of coastal cyclogenesis over the next day or two, but here is the current best estimate. Final Call be issued on Tuesday-

https://easternmassweather.blogspot.com/2021/12/early-season-winter-storm-possible-mid.html

I think the most prudent forecast at this juncture is a blended ensemble approach....the lighter GPS/EPS with the more robust GEFS to yield an appreciable moderate event. I have my finger on the trigger for Miller B east, though.

Yea, I certainly do not buy 1' in Boston....that ageo look is overdone...zero doubt.

I wouldn't forecast this right now, but I bet a lot of those seaward solutions end up as Miller B deals like the current GFS.

I think a lot of guidance being diffuse and OTS is a tacit nod to the GFS scenario because it can be inferred that the parent mechanics will not be that strong...ie ultimately it will transfer sooner...kind of like when the inverse scenario of when the inverted trough shows up on models as just a provisional solution until the model realizes not much will happen.

I'm making my visuals right now....I think its all about how quickly that energy transfers to the coast, which will be determine by how deep the parent system and how pervasive the polar airmass is. We want weaker parent energy and strong, stubborn antecedent polar air mass to induce a faster transfer to truncate the SW flow aloft....THAT is what will change this from a SWFE to a miller B. Could get best of both worlds, too, in the you get a SWFE, that then gives way to a miller B, especially north and east. 12z OP GFS shows this. You can toss the rules regarding how much snow you can get in a SWFE at that point because its no longer a SWFE..its a coastal.

GFS has that high hanging tough....not even retreating. Character of this event has really changed....PER GFS.

Its events out over the long haul....look at last January haha

@Isotherm Hope all is well, bud..see you browsing.

This is why it nukes from my area into Maine. Not ready to bite on that yet...emerging consistency, though.

GFS is closing mid levels as it passes...thats not a SWFE, but rather late-boom Miller B deal

Looks like the Hadley Cell ate it

You should trying fighting with Tip....its one of the most educational exercises imaginable. lol

The GFS must try to really sprout a coastal....totally gone wild that run. Gives me like 18"

I am trying to get a million things done today...saw that the Novie plot decently matched MJO 6/nina plot, and went out on a limb without checking and it blew up on me hahaha

I'm not arguing that it isn't biased in favor of S hem...I'll defer to your source on that. And its also very questionable whether it ever gets to phase 8, but there is plenty of evidence that it excites in phase 7.

Not the whole time. I was in an out running errands and didn't have time to pull up the MJO plot, but should have.

Before I viewed that graphic, it certainly appeared to me that the MJO had an imprint on November....probably like everything else, the truth lies somewhere in the middle.

Well, it spent most of the month in the circle of death...but the monthly composite looked an awful lot like what you would expect if it were impacting. lol

I created a lot of confusion by implying the MJO influenced November very much because it did not. However, I don't think its a coincidence that a lot of the long range guidance has the gradient look that is featured in MJO phase 7 during la nina composite, as the MJO reinvigorates in said phase.