December 2021 Obs and Discussion

Happy Meteorological Winter everyone! Glad to see some flakes lately to get us in the winter mood!

34* and overcast here in Albany. The forecast for tomorrow here is 48* and rain.

Thankful for a mild day today, going to decorate the outside of the house!

Regarding the threat on 12/8 there is very good antecedent air mass for snow especially for early December. The mid-level storm needs to stay far enough SE of the area to mitigate the WAA The best chance for this right now is NW of I-95. I liked what I saw on the EPS last night, but it's too far away for much enthusiasm from me. If I go by the H5 then this should be a quick flip to rain most everywhere. But sometimes even in bad patterns you can squeak something out as the pattern doesn't always dictate the individual event. Let's see if models can get better consensus in the next few days.

Models still continue to suggest an SWFE (overrunning event) is possible next Tuesday night/Wednesday. If the short waves remain separate and weak then consolidation most likely occurs offshore and it should pass SE of the area. I don't see a big SE ridge that will nudge this inland without early consolidation. These SWFE's w/out a really good high to the north pumping in fresh cold air won't favor coastal plain. This is why the AO is so important. When you have a negative arctic oscillation then you get those 1030mb+ highs to park over Quebec and work their magic.

I would think no snow accumulation for coastal plain and there is a potential for at least a few inches north of rt 80 away from the coast. That is the area I think that could be interesting on this one.

Roberto does a good job of explaining - the Monday system we need to dig a bit more and drag the cold air further down and keep the 2nd storm weak. If we can get that 1st storm to do some magic then I believe Rt 78 N sees their first accumulating snows of 1" plus - HV see 2-4" I'd say but NNJ 1-2". It may ultimately change to rain but the fact we are descending from a cold air mass pattern is as Ray alluded to in the LR 17-18 esque winter.



PS - the calls for blowtorch that some are making especially on line in the cease pools of SM need to quell their hype if you read some of these as models have kicked the can a bit - I do expect AN after this pattern goes to wayward but not to the degree some are portraying. Canada and the Arctic will be building a glacier bodes well down the road IMO. Also, Ural/Scandinavian HP and MJO phase 6 heat flux will aid in EAMT (East Asian Mountain Torque) engendering a knock around of the PV and displacement of the cold air baring any other developments.

GEFS colder than OP only 96 hours to go LOL!

12Z UKIE is keeping the storm much further offshore similar to 12Z GDPS with a less consolidate weaker storm and much colder solution. 12Z GFS energy is more consolidated and tracks overhead with a warm solution. Still 120 hours out and the verification probably lies somewhere in the middle. The antecedent air mass should be decent.

Another issue i'm seeing with the GFS especially, the surface Low is developing a bit too quick eastward IMO based off 500mb... the upper level energy profiles suggest the low should be developing a bit further south, it's common to see surface maps too eager with convection pic.twitter.com/46Jm9EFxAS

— NsfwWx (@NsfwWx) December 3, 2021

Many op models showing a fairly stationary 1030mb+ High parked over Southern Quebec. I don't think this is going to be suppressed and OTS with a decent WAR. That gives the coastal plain a chance at some snow if that high pressure is correct. The antecedent air mass is good for early December on this and I can tell you that high pressure CAD is often under modelled. It will depend on how far away from the coast the storm consolidates. Once again though NW of 95 are in a threat for several inches of snow especially I-80 and above.

heehaw453 wrote:Many op models showing a fairly stationary 1030mb+ High parked over Southern Quebec.  I don't think this is going to be suppressed and OTS with a decent WAR.  That gives the coastal plain a chance at some snow if that high pressure is correct.  The antecedent air mass is good for early December on this and I can tell you that high pressure CAD is often under modelled.  It will depend on how far away from the coast the storm consolidates.  Once again though NW of 95 are in a threat for several inches of snow especially I-80 and above.

Yes heehaw  Love where that high is sitting.  If you take a model consensus right now with the GFS further North and the euro uk met  Further South it looks like we could see our 1st accumulating snow of the season for many of us.  I know many will say with such a  Positive AO And neutral to slightly positive NAO it can't snow in the I 95 corridor but that is not what happened from 2010 through 2020 when those 2 indices were predominantly positive

18Z GFS is what dreams are made of. The storm consolidates fast enough offshore where it stops the WAA hence you get a very significant snowfall for the area. The high pressure also pumps in cold air at the mid levels. This would your absolute best case scenario. I wouldn't buy into any models until tomorrow night at the earliest. But I am starting to believe coastal plain can see some accumulation which for early December in this pattern would be noteworthy. Caution is my best word right now.

(Sighs heavily)……Fineeeeeeeeee, I guess I’ll formulate some kind of opinion on this event, since everybody seems to be excited for it lmao Short video discussion coming up for those interested.

Sorry for the delay, folks, but I apparently had to upgrade my computer's OS to be able to use my Google Drive in order to upload my video discussion lol Upload is currently progress, so I will post the shared link when it's done. Please note, however, that with additional time, it should also render in HD, but the initial video should still be of passable quality. Thank you for your patience!!

Ok, gang, as promised, please visit the below link to watch my discussion. I actually kept it reasonably short this time - only 13 minutes!!! haha

https://drive.google.com/file/d/1gonDCUaWVuA3Grk8Khi_qgno0tRQHRm5/view?usp=sharing

Anyway, a few things that I forgot to mention during the closing comments:

1. Another aspect that I don't like is how far west the main ridge axis starts - it's well off the west coast, which means that the approximate location of the long wave trough axis and associated pivot point will be located over the central portion of North America rather than over the Great Lakes, which is our preferred axis. So with the ridge axis being so far west, it puts us in a dangerous spot to allow further expansion of the Southeast Ridge.

2. If we lose too much mid-level energy during the trough split, then this will pretty much end up as nothing more than a harmless frontal passage, as the heights will remain flat with less dynamical forcing for ascent, and a development much too far offshore.

3. It is my experience that when you have so many factors supporting the thermal component, regardless of whether it's a cold or warm signal, the models underestimate it, and especially in these SWFE-type events and/or Ohio Valley runners, the warmth significantly outpaces guidance and the transition to mixed precipitation types/rain occurs much sooner than modeled. Aside from the issues I discussed in the above video, I have other indications that this would again be the case, assuming that the ideas presented prove to be true.

For good order, please note that the ideas presented here are all based on data up to and including today's 12z suites. I don't think that I clearly stated that in my introduction haha

I hope you all enjoy the video, and as usual, if you have any questions or comments, please feel free to post them!!

Now that I've had a chance to glance at tonight's 00z suites coming in, I like the trends aloft even though the surface maps are not yet where I think they will end up.

00z GFS Ensemble 500mb height anomaly trend:



00z GEM/CMC 500mb height anomaly trend:

RB love the video(not the possible outcome)...was easy to understand all the technical information with your explanations!!