psuhoffman

Wrt Friday...most guidance tracks the surface low over the outer banks and the upper low across southern VA. That’s a track that normally would get some snow into DC. And you can see hints at that on the moisture and RH fields. But the NS is nowhere to be found. A rotting airmass with a crap weak baroclinic zone so very little lift and no organized precip outside the convective banding under the upper low just NW of the surface low.

I think people are a little distracted.

That wasn’t a prediction. I still bet this works out to some degree. But DC is below where I would have expected right now based on the dominant pattern Dec 1 to now.

The surface low gained some latitude on the coast but the upper level low went w to e. It was snowing in parts of S VA while the low was still near New Orleans. You can get that kind of sprawling WAA snow shield when there is a true cold airmass on top and a better baroclinic zone.

Yes

He isn’t wrong that our results for having a +PNA-AO from Dec 1 on are pathetic. If the pattern does flip in Feb to a hostile one the fail will be that DC somehow failed during 2 months of a very decent to at times very good longwave pattern. No it wasn’t perfect but before people point out how this or that feature was slightly off from ideal...my retort is it shouldn’t take a freaking perfect pattern to snow. A lot of the warning events in our past were in good but slightly flawed patterns.

During a storm it’s dicey but they get the roads good pretty fast after the snow stops up here imo. Good luck!

It wasn’t really more powerful from a wave amplitude POV. The surface low was deeper and it had a huge precip shield because it had a much colder airmass to its north which meant much more baroclinicity (FUEL!) and more lift in the WAA to the northeast of the low center. But from a ground truth POV you’re correct even if this took that same track it wouldn’t produce the same result.

The miller b looks to be sparked by a vignerons NS wave that’s fueled partially by the increasing thermal gradient as the true cold finally enters the N Amer playing field. But the wavelengths look wrong for us, it’s likely to amplify too far north. Forget the damn miller crap the issue is simple that wave won’t likely have the depth to get a storm under us. But as that wave amplified the cold will come behind. What happens after depends on a lot of factors. Currently the guidance favors the cold centering to our NW in a gradient pattern. That’s actually not a bad thing provided the blocking stays strong enough to keep the boundary to our south. We don’t want frigid into the Gulf of Mexico unless your goal is to walk across a frozen Potomac.

2018

We didn't really give it much time though...the pac is just backing off now. Maybe after a week domestic cold would be enough. Or maybe not...I have been disappointed recently in what native airmasses look like absent cross polar flow.

It's not really a coup though other guidance has been hitting that also. We had 2 euro op runs...the ensembles this run, and there is "some" degree of support on the GEFS. This is not high probability yet but its not praying for some obscure model to score a coup either. Its a legit threat, and definitely the best one we have had since mid December.

it's about pain management. The look could change. I don't have a crystal ball. But its been a very clear signal across all guidance there...and I know what history says about how that setup ends for us. I would rather just resign myself to it now...then torture myself over what is "likely" not definitely, not going to end well for us.

I love when an ensemble at range shows a deform signature in the mean precip over our area...there must be some really nice solutions in the mix to see that on a mean.

ya I'll hug that

yay for them

I didn't want to say it...but that's possible right now. I am curious where things go after. It looks to be setting up an EPO ridge -AO/NAO look. That is super rare. They also can be wildly variable. If the EPO ridge is far enough east its an EPIC pattern. But if it retrogrades too far west it can be a frustrating cold/dry warm/wet pattern. What is your gut on that look?

I personally would have preferred the N PAC trough back off some but not totally leave the scene. But everyone wanted some huge EPO ridge to get arctic air into the pattern. And it looks like they will get it. There is a trade off though. That is not as good a HECS look. It opens the door to cold/dry. It also could lead to enough SE ridge that anything that phases and bombs could cut west of us. I want a BIG storm so I would have preferred the other look. But if you just want some cold and snow this is probably a better look. It just depends what your preference is.

Just getting this out of the way...there has been a VERY strong signal for a NS miller b system around the 15/16th across all guidance for days now...and its only getting stronger. That storm is going to miss us. Its going to screw us over. And its going to likely dump tons of snow on the normal places to our north...and resign yourself to that now so we dont have 20 pages of woe as me posts when it happens. That is NOT our storm...if by some miracle the blocking forces the NS to dig enough great and then we can enjoy it but just get over the idea now so it doesn't torture you for the next 10 days. Our legit threats are the period before that and after it.

At least we get to watch that miller b blizzard New England at the end of the run.

The cold comes in behind the northern stream miller b type system around the 15th. That is VERY likely to go to our north...then the cold hammer comes down behind it.

We're gonna get Miller B'd at the end of the run lol

Agree...I am totally fine with where things are right now. But I also share your (and others) frustration wrt the the result we just looked at...and it seems to be a theme we are seeing a little too often in recent years. All those flaws I pointed out are real but imo they are a better excuse for why it wasnt a big storm...not a good excuse for why it was a 37 degree all rain event. It didn't used to take a freaking absolutely PERFECT setup in every way just to get some snow around DC. Lately it seems unless its absolutely perfect in every little way its not happening. Its either HECS or nada lately. There is one obvious elephant in the room that could be the cause of some of that.

This next wave is still (frustratingly) coming before we really have any true cold to play with. So a weak shearing out wave is not going to work. We need the system to be amplifying on approach not washing out. It's going well through like 120 and then a combination of things go wrong imo. The flow is a little too suppressive. I know that sounds crazy when its so warm but the flow can't totally fix the lack of cold around. And the system splits and leaves a piece behind (probably in response to the shred factor its crashing into) and in response the wave starts to weaken and shear out. The weak POS wave left when it gets to us won't do us any good. We need an amplifying upper low passing just to our south OR NS phasing to infuse colder air for this to really work (like the last 2 euro runs) a weak all southern wave wont cut it when the antecedent airmass is still crap.

The trough splits the energy again and strings out...so the wave is deamplifying and shearing out as it approaches which won't work because the airmass still isnt good. We need a bomb...a weak wave won't end well.