Cobalt

The fabled Pac-Man pattern? No wonder people are bringing up analogs from the 80s. 

39 minutes ago, CAPE said:

It's December. The favorable pattern is just getting established. You'll take 2-4 with sleet and rain and be happy.

The setup leading into it is nowhere near identical (in the sense that we're dealing with a major Midwest storm as depicted on the models) but the lack of major costal development and angle of precipitation as shown on the GFS heavily reminds me of 12/16/10, another event where an episode of blocking was becoming established. To my memory that was a clean 1-3" during the daytime, and a nice early sendoff into the winter break. I have yet to look at the h500 comparisons though, but the PNA was not all that favorable for that month either.

GFS is definitely feeling the block

4 minutes ago, Maestrobjwa said:

Around here, I find that snow dreaming only makes it worse if it misses, lolol

Seeing the advertised pattern around the holiday season heavily reminds me of that late December 2017 pattern that had shown glimpses on nearly all the guidance for a few days. I was a young impressionable weather enthusiast, so all of the monumental operation runs (and ensemble runs with high snow means) gave me the complex of a gambler winning jackpot after jackpot, and sure enough, the rug was pulled just a few days later. Pretty good introduction to keeping snow expectations in check at least! 

Funnily enough, the EPS keeps the central area of our subforum near normal temperature-wise for the next 10 days.. Culprit is probably the consistent storminess being caught under the block, so after our brief warmup (+3-4F for the next 5 days), things look to cool down a bit from D5-D10. 

EPS +0-1F, GEFS +2-3F. All eyes are on the pattern after this timeframe, but definitely not a "torch" look as we head towards mid-month, despite poor airmass quality. 

3 minutes ago, Cobalt said:

Not sure why people are all that excited about Artificial Intelligence.. this thing is clearly digesting false information (OpenAI Chat Playground)

Not sure why people are all that excited about Artificial Intelligence.. this thing is clearly digesting false information (OpenAI Chat Playground)

27 minutes ago, nj2va said:

Worry posts spread like wildfire in the LR thread - if the 12-17th window gets pushed back to the end of December, it’ll quite literally be a dumpster fire of moaning and groaning.  We’ve seen delayed = denied but I have a hard time believing we come out of the upcoming advertised without seeing any snow (unless the thing just goes poof in the next 5 days which seems unlikely).  We also have to remember total annual snowfall in DC is like 15-20” depending on where you are in the immediate metro area…coming out of this pattern with a 4-6” moderate event is climo.

I think this is an extra layer to the worry for some people as well. A good pattern will necessitate that the nail biting over long range pattern trends turns into nail biting over medium/short range threats and their respective modeled outputs. We don't do uncomplicated setups that often, especially in Ninas, so it can be difficult not to sweat over threats until you're watching snow falling out of the sky (and even then people will worry about the back edge, dry slot, etc). That's why last January was pretty special for me, we had 3 relatively uncomplicated setups that all gave sizeable snows before the pattern was supposed to "get good". Even then, there were still substantial winners and losers in each threat.

1 minute ago, WxUSAF said:

It’s not just us. The SNE weenies are doing the same thing. For lack of a better term, good patterns often have to “marinate” for a bit before we get snow out of them. Isn’t always true, this past January being a prime example, but it is more common to have to wait. With the AO and NAO looking like that, I think a generally favorable environment is going to stick around for awhile. And are many people really going to complain if our better snow chances are in the week leading up to Xmas vs Dec 7-12??

I think it's the worry of delayed becoming denied. As you've mentioned, we are in a much better position to can kick this early in the season, but it's hard for some to view it that way when whatever is on the other side of this pattern isn't in the medium range yet. Once those trackable threats begin to show up, people will loosen up a bit. 

1 minute ago, WxUSAF said:

I think I’m as optimistic as anyone about this pattern and I have two assumptions:

1. It will probably take longer than “expected” to get snow out of this upcoming pattern. 
2. Our December snow climo sucks, so a “good” productive pattern this month might still result in like 3” for DCA and 4-6” for BWI and IAD.

Winter’s back!!

I think our lack of experience with modelled -NAO events is also hurting our sense of time with this upcoming pattern. The one I can remember somewhat vividly is the late Jan 2021 blocking event, where both the GEFS and EPS were spitting out super cold and snowy 10-15 day looks starting around the 5th of January. It still took until very late into the month to get any meaningful cold, and basically on the cusp of February for meaningful snow. That was at the heart of snow and cold climo, so us being in December definitely can't help in those departments. 

While the trends in pattern progression look to mimic the 18z GFS through the medium range (not good), the 18z GEFS also looks to be picking up on the potential 9th/10th event.

A few scattered hits and misses on the individual members, but the idea is there.

Weeklies try to keep the party going through Christmas.

BWI: 17.4"

DCA: 12.3"

IAD: 17.2"

RIC: 11.1"

Tiebreaker (SBY): 10.8"

15 minutes ago, Weather Will said:

WB 12Z EPS is not the GFS toaster oven…

Interesting that the EPS and GEFS now have the PNA nearing neutral around the 13th. Perhaps that could be an early storm signal with some brief west coast ridging?

Alongside -EPO, and AO/NAO relaxing from their -3SD minimums. Probably too early into the pattern's progression, but worth noting. 

-NAO signal on the EPS continues to get more impressive, a 3.4 sigma block appearing as a D12 mean is something.

The days leading up to this regime change don't seem particularly toasty either. Some strong + and - temp variation, but the EPS has the first 7 days of December nearing average. 

Just your casual 6-12" November snowstorm followed by single digits and sub-zero temperatures. 

3 hours ago, Eskimo Joe said:

 

That look on the EPS reminds me a lot of November 2017. Not identical, but overtop there are definitely similarities to the start of the month in both figures. 

Chilly day on tap for Monday

1 minute ago, klw said:

Last big wave almost swept one guy out and almost drove another into a pylon.  They look to be leaving now.  Things really picking up as a band moves in

Looks like they're back

2 minutes ago, H2O said:

Hellworld

was debating on posting that there, awfully dystopian.

bring your pets if you feel teh need 

Looks to be relatively chilly closing out September. A rarity given current climo. 

Eurasian snow extent is off to a pretty decent start. Compensating for North America's sluggish (lowest in the dataset to date) snow extent atm.

46 minutes ago, MN Transplant said:

Want some depressing stuff?  Here are the temps from around 1900 vs around 2000.  Departures from current norms.  Yeah, we can still pull off a Dec. 2000, or Feb. 2007 or 2015, but woof.

 

 

yeesh