40/70 Benchmark

Semantics...I don't mean LBSW as in occlusion. It gets shunted further se the more ne it comes.

I may just need ro rinse this 12 year la nina out once and for all and start with a clean slate.

Watch the block be strong enough to crunch Monday, but not enough to deflect Friday far enough south.

12/12 is a lost cause for me....Ground Hog day finding a way to LBSW. Need the one after because if that is rain, I may lose it early on.

Some of the best snowgrowth possible. I was in NC for that one

Yea, I was never concerned about supression this month, aside from a rogue SW that gets sheared by some compression between NAO and RNA.

We take this all day/every day in December.

I think there should something like the old EE (EURO/ETA) rule for when you and I agree.

Exactly as we expected mid December.

Agree....first several days of the post 12/10 period are a bonus.

Gist of the blog post I just made...'"Double Jeopardy" next week.

Block looks better relative to 00z....lost that silly ULL W side of Hudson's Bay.

Active Mid-December Pattern Poised to Take Shape Book-End Threats to Begin & End the Work Week As we begin to approach the all important holiday period, the more active pattern post December 10th appears poised to begin as advertised late in the month of November. The first of two winter storm threats is slated for Monday. In the annotation below derived from the 00z Wednesday ECMWF ensemble mean valid late Thursday night and early Friday morning, it is apparent that the shortwave is careening to the east and towards a compressed flow between the fledgling NAO block to the north, and mature southeast ridge to the south that is in response to the deep west coast trough. In fact, that southeast ridge is so pervasive early on that it initially causes the fledgling NAO block to conjoin with it, which both acts to negate the influence of the negative NAO and cause a very compressed flow. This compressed flow acts as a source of deconstructive interference for the shortwave that is very reminiscent of this past December 2021. Towards the end of the week, the shortwave continues to struggle in the compressed flow and attenuates to an open wave over the Ohio valley by late Friday night and early Saturday AM. Note the absence of a notable gap or area of lower heights between the south east ridge and NAO block. However, by Monday AM, the southeast ridge begins to relax as the west coast trough matures, which creates separation and falling heights in between the two ridge nodes in a more traditional configuration. This in conjunction with the strengthening NAO block that is becoming better positioned to exert enough an influence to reduce the compression to the flow allows the storm to quickly begin to re-amplify and close off as it exits the coast. The trend began to emerge yesterday, as the NAO block began to distinguish itself from the southeast ridge and exert more of an influence, faster, which allowed for quicker re-amplification of the exiting wave. Just how quick this system is able to amplify and produce the first significant winter storm of the seasons for the region is dependent on two factors: -Just how close is the major storm over New Foundland. It is is too close, the coastal storm will not b able to amplify as far to the north, and may skirt southern areas of the region. -How strong is the NAO block and where is the ridge axis in the plains located. A weaker NAO block allows the ridge axis to progress further to the east, which will force the redevelopment of the storm later/ downstream and further off of the coast. However, a stronger NAO block will tend to slow the flow down, which causes the plain ridge axis to be further west, and accordingly, the downstream coastal also amplifies further to the west/closer to the coast. The Newfoundland low dictates to a large extend how far north the system does or does not get and the NAO block determines whether or not the flow is too fast to allow the system to amplify close enough to the coast for the northern extend to matter. OPTION 1: One possibility is on the benign end of the continuum of possible outcomes. If the Maritimes low near New Foundland on Monday ends up slightly closer to the region (further south) and the NAO block weaker, then the developing coastal will be develop later (further east and off of the coast) and not allowed to amplify (squahsed to the south). This represents wither no storm of a very minor impact. OPTION 2: However, if the Newfoundland low is slightly further to the north and the NAO ridge stronger, than the storm develops faster and amplifies more to the north. This would represent the first major winter storm of the season. It a blocked pattern like the one that is developing, it is likely that whatever happens next Monday will impact what happens further upstream, on Friday. Double Jeopardy There is the potential for the development of another major coastal storm (get used to this) on or around Friday, December 16th, which, is signaled well via teleconnector convergence. Thus the degree to which the Monday system can amplify and just how quickly it can do so will have a large impact on how much resistance it can provide to the Friday system taking an inland track. OPTION 1: A more intense and slower to exit first storm acts as a "50/50 low" to work in tandem with the resistance provided by the NAO block to induce a more rapid and proficient transfer of energy from the primary tracking through the Great Lakes, to the secondary coastal development. This results in (another) major winter storm with a potpourri of mixed precipitation that would produce major travel headaches to end the work week. These type of systems are referred to as SouthWestFlowEvents (SWFE) due to the prominent southwesterly flow aloft that results from warm air advect in he mid levels of the atmosphere due to the dying primary low. OPTION 2: The first storm is less and intense and faster to move out, which while this is still likely to force the ultimate development of a "triple point low" at the surface near the coast (limits low level warmth), most of the precipitations falls as rainfall after perhaps a very brief bout of wintry precipitation near the onset. Travel impact is limited. Clearly given the state of the Pacific pattern, the key to an early and aggressive onset to winter here in the eastern US is heavily dependent on just how pervasive a force the NAO block can become and thus how proficiently it can offer up resistance in the flow. While the result is likely to fall somewhere in the middle of the continuum of potential outcomes, the trend is to increase the risk for a more noteworthy initial onslaught of winter 2022-2023 next week. Stay tuned for a potential Friday issuance of First Call with respect to Monday-

Models won't accurately portray a very blocked flow until it sees the whites of its eyes, no pun intended.

Still trending IMO.

Before 12/20? Nah...

I'll probably miss that to the southwest, then the Friday deal is good for NNE.

https://easternmassweather.blogspot.com/2022/12/active-mid-december-pattern-poised-to.html

Yea, that is what I focused on instead of the ridge location that Brooklyn did.

Nobody can get enough of those...keep 'em coming

Hopefully it misses, but is still strong enough to alter 12/15

Yea, formidable showing of the movie Groundhog Day.

Stunner.

Just unreal.

You are correct. I missed that.