eduggs

The 0z GFS still looks pretty solid. General mean of 0.1 - 0.3" liquid across all guidance. The radar is a little ragged but slowly building and snow isn't expected until just before dawn. Do we get cranking or does it fizzle? Nowcast in the early morning... 0.25 liquid over 8 hours is a fairly respectable average intensity if it happens.

Not much margin for error since the cold side precipitation is unlikely to be extremely widespread. But run to run changes are decreasing in magnitude and most mid-range guidance appears to be converging on at least some wintry precip. locally. Obviously a fringing or ZR to rain are still possible but the envelope appears to be shrinking.

Wintry 5 days on the GFS! Might even squeeze in some flakes or ZR on Xmas day in the weak wave in between the Tue and Fri night events.

Both GFS and GFS-AI ticked slightly further north vs. 18z. Still snowy (some ice SW) for most areas. Kind of the sweet spot right now.

HRRR (01z), RRFS, and ICON are a little juicier than the NAM: 0.2 - 0.3 liquid for NYC. Heaviest band could be fairly narrow. Snow accumulations along coastal plain likely intensity dependent. So far no obvious change at 0z.

Some flakes reported on mPING in northern MD near Hagerstown with the initial finger of overrunning. Latest HRRR and current radar look decent. Hoping for a good burst of snow in the 5am - 11am timeframe. If moderate or better rates materialize, it should accumulate for most.

I'd feel more comfortable too with colder temperatures but this airmass should support accumulating snow in most areas away from the coastline. Yeah should drop a few degrees when the lower levels fully saturate. Before then the temps are likely to rise as clouds move in and then stabilize or fluctuate slightly. Should be approx. 30-36 until precip. starts and then 30-34 (elevation and location dependent) with mostly snow late tonight.

Maybe this misses south. But I say, let's get to the modeled cold side first to avoid rain and then hope it nudges north in the short range when model changes tend to be smaller.

This could be either a great local NWS forecast or a terrible one. With multiple days of 0.1 - 0.3" liquid model forecasts with a snow-supporting model profile across the interior... forecasting <1" of snow accumulation is ballsy. I respect the conservative approach. And there are reasons to be cautions with an unfavorable angle of precip. approach, non-uniform precip. shield, and possibly above freezing surface temperatures. But if it turns into a messy morning commute, many will be unprepared.

0z and especially 06z EPS mean and members show some serious CAD on Friday. Love the thermal gradient even on the means, with mid teens in ENY and 50s in SWPA. If this stays south or shifts further south we're likely to lose some of the QPF too, which is a fair tradeoff I think. We could also see a snap back north today after a major shift south. Fun times when there are multiple threats inside 5 days to track!

Don't even look at the GFS "clown" maps for Friday. You will not be able to unsee them.

That's a big shift from the GFS. It represents the southern edge of its ensemble spread from 12z and 18z as well as several of the ECM ens members. We pray! If it's real we would expect to see movement from other models over the next day or two. I'm doubtful for now but the ECM has been hinting at this possibility...

0z GFS has a significant snowstorm for Friday.

I don't put too much stock in the GFS-AI, but it's showing snow and ice for Friday 12/26: >0.5 liquid with surface temps at or below freezing NYC north throughout the event. It has hinted at this wintry outcome for several cycles. There is a little support amongst the ensembles, particularly the ECM suite, but the majority of mid-range guidance takes the boundary well north of us, favoring NNE for wintry precip.

The WPC maps have <10% probability for 2" of snow in the far northern reaches of the OKX forecast area, including elevations above 1000ft. That should have nothing to do with "white rain." Those areas might not get 2" of snow. But I would like to know what the basis is for assigning a probability of less than 1 in 10 chance.