WxUSAF

12z GEFS is notably less bullish with ridging over the pole after Tday, but the pattern still looks spectacular. Builds the AO late in the run. But rocking -NAO and +PNA and clear signs of a busy STJ.  First week of December should have chances.

How about another coastal after thanksgiving @psuhoffman?  Warm rain though.

Without being a weenie, I’d say to ignore the Canadian (look how far northwest the track is compared to the rest) and weight the GFS thermal profile low relative to the euro and 3k nam.  This is an interesting test for the FV3. It’s been colder than the op GFS on this storm so far. 

Between the forecast 500mb progression and signs that the strat vortex may get disrupted around the 1st, I think it’s fair to say that we’ll start December with a -AO and perhaps a strong -AO. Question now is how long it lasts. But another good sign that a blue ball of death can’t form over the pole so far to start the winter. 

3k looks rough. Enjoy seeing a few flakes and pings before the deluge.

6z euro went toward the gfs apparently.

9 minutes ago, C.A.P.E. said:

Yeah both the GFS and the FV in recent runs have a low moving well south off the SE coast. 0z Euro op has a northern low that would appear to be too warm around day 10, but looking at the EPS there are several members hinting at a coastal low off the SE-MA coast. Something to keep an eye on in future runs.

With that advertised longwave pattern, I’d expect the op runs to start teasing us in the next few days.

14 minutes ago, psuhoffman said:

That's about where I am. But this has high bust potential both directions. The whole thermal boundary is close. And models can't usually nail every level to to the exact degree. In this case a 1-2 defree miss in either direction for us is the difference between mostly just cold rain/sleet and 5" of snow. 

It does have bust potential, but I would go off our climo and past experience. Low level cold holds on longer than expected, but mid-level warmth comes in faster than expected.  That’s a recipe for a lot of sleet I think. I’m thinking that snow may be restricted to your area and the mountains, with the rest of us just going sleet to rain. Hope I’m wrong and see a few fatties, but I’m leaning against it right now.

I’ll eat my phone if I get 6”

23 minutes ago, nj2va said:

Overall, I’d say a step back but the positives are quicker precip and cooler 850s at onset.  Precip starts in DC by 12z (0.1” already fallen by 12z in DC in the 18z run vs the 0.1” line SW of Manass at 12z run)..  850s slightly colder at the start.  Surface starts a touch colder in places but its a warmer run at the surface overall than 12z.  Looking at the verbatim 10:1 snowfall maps, definitely cut back...2.5” runs through DC vs 4.5” at 12z.  

Thanks. Makes sense. Seems like we’re converging on consensus with the euro on the cold side and GFS on the warm. 

2 minutes ago, nj2va said:

Yes.  Looking at it now. Precip comes in quickly and cools the column nicely...850s in DC go from +1 to -3 from 9z to 12z.  But surface is 34 in the city and warms to 36 in the afternoon.  You stay at/below freezing at the surface until overnight into Friday.  

How does it compare to 12z?

If I had to handicap it for MBY, I’d go with:

seeing some snow or sleet: 90%

measurable snow/sleet (>=0.1”): 70%

1” or more: 40%

2” or more: 10%

Just now, Jandurin said:

This storm needs to get within 48 hours.

Lucky for you it already is?

Per other websites, euro soundings support 4-6hrs of snow near BWI.

Just now, WinterWxLuvr said:

I'll bet watches are coming before this day ends.

Likely for you, yes. Borderline for the M-D line zones probably. 

Ha that Canadian map is basically a weenies dream. Textbook.

FV3 gets a stronger press from the cold high which looks to counter the slower ULL pass. 

Nice work, Matt (and Jason)!

GFS pretty close to 6z. Maybe a touch warmer. Better for the far N+W crew because precip comes in faster resulting in more snow to start.

4 minutes ago, North Balti Zen said:

Just depends on people's hopes/expectations. Based on the tweets I put in the other thread, if we can eke out 1" at BWI and/or DCA...it would be first time doing so in November since the 90s. That's maybe doable...maybe. At least, more or a worthy hope/chase than the crazy 4+ inch amounts inside the beltways.

DCA has precisely 0.0000000000000000000000000000000000001% chance of recording 1”. 

BWI’s odds are probably a bit higher.

3 minutes ago, Bob Chill said:

I'm not all that excited for thurs. Early season storms almost never produce in my yard. I'm prepared for watching whatever minor slush that accumulates run down the storm drain while northern tier folks post winter wonderland scenes every 5 minutes. 

You’ll take you slush dusting and LIKE IT.

1 minute ago, Buddy1987 said:

Is the 32k nam reliable in peoples opinions here compared to the 12k and 3k? I’m trying to figure out how much stock to put into it when looking at factors for Wed night/Thur such as 2m and 850 temps, etc..

No. It’s just a downsampled version of the regular NAM. The 3km NAM is the only one to ever look at.

1 minute ago, WxWatcher007 said:

 

Would anyone ever call for 25+ at DCA before the first flakes have fallen? What were the 09-10 forecast totals?

CWG went 150-175% of normal in 09-10. 24” for DCA and 30” for BWI.

CWG winter forecast is out. Slightly warmer than normal DJF, rocking Feb and maybe March. 16-24” for DC.

9 minutes ago, Scraff said:

How’s the Euro look for the likes of you, me, and @osfan24? Think we can score 1-2? Will I see you at the top of the sledding hill? 

If the euro is locked in with that solution, we will likely see some accumulation. Congrats @mappy.