Cobalt

AI GFS continuing its trend of shifting the trough West

It had that northern stream component notably West early on into the run like NAM and Euro, but then yeah the entire look fell apart.

Quite funny that it has that early March 2010 fail you brought up a bit earlier as the #1 analog. I remember reading that that was a stone's throw from a significant event, but don't know much about it otherwise.

12z didn't have precip within 50 miles of DC, so a definite step up on the surface side of things.

Decisive steps in the right direction the past 2 GFS runs.

Might be weenie folklore but it's only fitting that this window is showing back up as our current system is exiting stage right. GEFS is still offshore but beefed up, a lot of monster lows within range.

2015 all over again.

Still at 13 degrees with heavy sleet in Harrisonburg. Nuts.

Looks like you're getting quite the prolific storm up there. Would love to hear your observations, enjoy it!

Eyeballing from my window but maybe 2-3 inches? Grass is completely covered, and it already looks like the sleet has tried its best to cover up some of the pathway footprints. 12+ hours of this stuff might match or exceed our snow total.

Those yellows to the southwest of y’all look like they want to break free from the CC sleet line. Hope you guys get crushed with that stuff. Solid snow back home in NoVa, meanwhile we’re constructing the next glacier here.

It’s a bizarro world, down to 9 degrees with moderate sleet here.

IIRC most of the mesos had me flipping 1-2 hours before DC did. Perhaps the sleet line is going to halt after this quick advance but TBD. This does open up a shot at a ridiculous sleet storm, as the HRRR suggests 1.2" QPF is to fall from this point onwards. If a majority of that is sleet.. woof.

Harrisonburg

Suspicions were right, hearing sleet mix in now.

SN+ at 10 degrees, probably a once-in-a-decade type obs combination around here. Huge huge flakes.

Absolutely gargantuan snowflakes right now. Was gonna take a nap until 5am but this is compelling me, especially with that sleet line to the Southeast. A flip to sleet would be hours early, and I'm hoping this increase in flake size isn't signaling that outcome. For now, SN/SN+.

Euro clips the SC/NC coast, 989mb storm offshore. It's not particularly close to us but it isn't 500+ miles OTS like the 12z. EPS is about 0.15" QPF for DC in that window. Not much but a step in the right direction.

The type of observation we're gonna look back on years from now. So curious as to what the coldest ever sleet observation is, that's gotta be close. 11F with -SN/SN here.

11F, -SN. Perfect conditions for the dorm fire alarm to have gone off and send everybody outside..

11F with -SN. Larger flakes starting to pop in with the pixie dust. Seems to be go time! Might be the last time I see bare ground until the second week of February, kind of incredible.

The rates right before the flip would be very nice. 0.1-0.2" QPF in an hour, probably some huge silver dollar style flakes before the changeover

16 degrees in Harrisonburg

GEFS is pretty enthused at this range

Before the upcoming cold snap.. DCA currently sits at 37.7F for the winter, 21st coldest winter since 1970 (arbitrary cutoff), and 0.7F below the 1981-2010 average. That figure is most certainly going to drop, but I'm not sure it can be overstated in how potentially prolific the upcoming cold snap will be. 12z GFS' raw output for temps at DCA has the 24th-31st averaging 17.6F, which would be the coldest on record for that time period. For a laugh we can take the Euro's output from 2 days ago (the most recently accessible chart on the weathermodels site) to find that it has DCA averaging 12.2F for that timeframe. The Euro has an obvious cold bias with snow cover and IIRC has backed off a bit from that ridiculous number, but all of this illustrates how potent the upcoming cold will be. The "tamer" solution still challenges the coldest last week of January on record.