DarkSharkWX

3 hours ago, psuhoffman said:

 

What CBM said. The low heights on the mean are from two bowling bowls that progressed through after cutters. As both shortwaves were approaching the critical area there was a WAR and full latitude eastern ridge in front. 

Fair enough - I can see what you mean; still wouldn't say pattern was dominated by SER/-PNA, and as others have said sometimes its just luck(if the frontend was colder for just a bit longer or it snowed for a bit longer in the right areas we would have gotten accumulating snow)

Just now, cbmclean said:

Interesting that in that composite no WAR really shows up, but we know it was there when it counted.  You can also see that the mean trough is much further west compared to say Dec 2010 or March 2018 which itself hints of higher heights in the SE.

Yeah most of the cold was placed in the Central US because of the lack of a 50/50 low and the ridge not being east enough over the Rockies. Had we had those 2 factors, this December could have gone a lot better

Just now, AtlanticWx said:

yep! here you go

much more different lmao

1 minute ago, Maestrobjwa said:

And that -PNA....The more neutral/slightly positive look being shown on guidance a couple weeks ago never really verified, did it?

From Dec 15(around time when we were expected to go into a favorable pattern) - Dec 24(latest date available) there doesn't seem to be any sign of a -PNA/SER at all. The PNA not being east enough(not over the Rockies) and the lack of 50/50 are one of the factors that contributed into the pattern not doing well.

5 minutes ago, psuhoffman said:

Good test of guidance v analogs. Several of this years analogs are in that set and they say don’t get your hopes up. The guidance says we head a different direction than history suggests. Place your bets. 

tbf correlation doesn't equal causation - most of those years that had <1" for you before Jan 1st were bad for everyone because of a strong -PNA and SER which is different from what we've had so far and what is being shown on guidance

the reason why we will go AN for the end of dec thru first week of jan is because of NPJ overextension - quite similar to a strong nino pattern

16 minutes ago, psuhoffman said:

Off the top of my head I think the non Nino years with less than 1” were 1949-50, 54-55, 58-59, 75-76, 80-81, 84-85, 2001-02, 16-17, 19-20 

Based on NOHRSC, Manchester got only 0.1-1" during 2021 before 2022, and was a non-Nino year

12 minutes ago, AtlanticWx said:

one thing i particularly like about the upcoming pattern is that we don't have to worry about much going wrong. the pacific jet is currently over extended and we actually want a retraction which is quite easy to get in a niña iirc

as long as that ULL near alaska retrogades and become an aleutian low, we're in business for january. ❄️❄️

and looks to be a legit +PNA over the rockies and a ridge bridge along with +SCAND in our peak climo

the +SCAND should eventually build into an -NAO and that along with the aleutian low will put pressure on the pv

All we need is a Canadian high, a ridge over the Rockies, and a 50/50 for a big snowstorm, high-latitude blocking/-EPO aren't necessary(though they obv help)

This certainly isn't a horrible look

10/-4 with -10 windchill in Gaithersburg now

12/-2 with -7 wind chill in Gaithersburg

28/25 gaithersburg

1 minute ago, AtlanticWx said:

fwiw the R/S line drops back east too, with bursts of snow across moco/hoco, temps are riding the 0C line based on soundings so a degree difference can result in an overperformer for a lot of ppl. getting good vibes from this one

CAD over preforming rn

3 hours ago, CAPE said:

Latest GEFSx gets us to this look moving into the second week of Jan. Based off the 0z GEFS run from yesterday that goes out to Jan 3. Should this progression transpire, mid to late Jan should be colder than normal, coinciding with near peak climo for cold/snow.

That would be putting stress on PV, with the Scandinavian ridging/high and low near the Aleutians. Good pattern for PV disruptions.

GEFS has the signal around 27th now

I wouldn't fully give up on this system yet, there is front-end thump potential as well as some potential for some backend snow. If this threat doesn't work out, we also have the 27th to look to

NPJ gets too extended which brings warmer period and pacific puke, however maybe the 27th threat could work out before we switch to a warmer period

New WPC forecast shows 10-50% of exceeding .25" of snow/sleet(liquid equivalent) for much of the mid-Atlantic/northeast, and even extending down into the southeast.

7 minutes ago, Imgoinhungry said:

Anyone in Frederick county MD hit the roads yet? I teach and mcps but first grader is fcps. I teach mcps while kid is fcps. Wondering if fcps will remain on 2 hour delay or close. Assuming mcps stays 2 hour delay. Need to figure out childcare plans…


.

FCPS will most definitely close because of the widespread icing that is expected to continue(as well as the ISW), and MCPS might close as well.

Here's a wetbulb calculator if anyone needs it(<32 Tw freezing rain, >32 Tw rain):

https://www.weather.gov/epz/wxcalc_rh

Looks quite icy outside here in northern MoCo. 32/30 with Tw in 30-32F range

Does anyone have FRAM on pivotal for the latest HRRR?

Wetbulb temperatures for DC and north are already 32 or lower. A study found out that the best wetbulb temperature for ZR is 27-30F, which isn't that off and will reach further south as temperatures drop.

Got to a low of 18 here in Gaitherburg, colder than I had expected. Right now 37/17