high risk

Regarding Thursday, we all know that the GFS is terrible with cold air damming, and the evaluation period for the GFS para found that it was notably better (still not great). Assuming some skill with the synoptic details, we can see evidence that Thursday will be colder here, especially in the morning hours: Not saying that this will be a snowstorm, but the chance of another ice/sleet event is probably higher than we realize right now, especially if the precip arrives in the overnight hours Wednesday.

One more time for those in the back: .02" of freezing rain is a high-impact event if it's in the 20's and has been for hours leading up the event. That said, there is a clear signal in the CAMs, the parent NAM, the GFS para, and the 18z GFS for sleet at the start for most of the area except for southern MD where it's all ice. Having a coating of sleet first would certainly lessen the impact of freezing rain on surfaces, although I still think that it's going to be unpleasant walking or driving tomorrow and tomorrow night.

NAM and NAM nest do have a bit more precip arriving during Saturday, but it's mostly sleet until later the day. At that point, it turns to freezing rain, and there is nice slug of it in the nest over southern MD, but the precip field everywhere becomes pretty sparse by 00z. (Worth noting that the 12z NAMs were highlighting the period later Saturday night for the best ice threat. We will see if 18z continues to have heavier precip during that period)

Yes, and the NAM nest actually waits until after midnight Saturday night to get its heaviest precip going.

No need for apologies. We're all used to hunting big QPF for winter events, and seeing some models showing 0.05 to 0.1" liquid naturally evokes a 'meh'. We all just have to remember ZR, no matter the rates, is a nightmare when you have it falling with temps in the 20s onto surfaces that are "cold" going in to the event.

Can't emphasize enough that even .01" of ice with a cold antecedent air mass can be an absolute nightmare on the roads, as shown in Ft Worth yesterday. As noted by @chris21the 12z HRRR verbatim is certainly a high impact event - plenty cold, and modest rates (which help accretion), but plenty dangerous on the roads and sidewalks and enough total QPF to threaten some power issues in areas where some of the (patchy) higher amounts fall.

Definitely worth remembering that when it comes to freezing rain and temps in the 20s, even if model QPF drops from 0.4" to 0.1", it's still a high-impact event.

This forecast yesterday from the NAM nest (using 10:1, since snow depth maps failed due to the warmer soil leading in) wasn't too shabby:

huge flakes mixed in with the pingers

I wouldn't recommend hanging my hat on the GFS para snow maps. Maybe it's right that it will snow in DC (although there seems to be a consensus for sleet turning to rain), but it keeps the surface at 34/35. That's not going to get the job done for accumulations, even at night.

I do like this model, but I suspect it's a bit wet for tonight. I sure do love where it puts the heavier stripe:

Hug the 12z NSSL-WRF!

The NAM also led the way on insisting that it would be significantly warmer at the surface.

Really need to focus on the NAM nest over the parent here. We've seen the parent NAM be too wet in the short range for several events now, and it sure seems that way again. The nest looks far more reasonable. The nest also keeps DC and areas along and south of Route 50 as a mix going to rain, and that makes sense to me again (with the parent slightly further south with the rain-snow line).

This is 2 cycles in a row that it has shown this. Being at night will help overcome it a good deal, but it's weird to see the NAM be the warmest model so far for the event.

Their details with wave 1 are quite different, but by Friday, the Euro and NAM generally agree on the biggest totals being south of DC (and perhaps well south), with a nasty cutoff for those living further northeast of DC.

I sure don't hate this run.... but people in southern MD most certainly will.

Great point. The difference in snow maps for the NYC area tomorrow between the 12z NAM and GFS is pretty crazy for this short of a lead time.

Definitely, but capturing the position of a boundary and critical details of the related cold air damming is still contingent on having the background synoptic details correct. Once we're confident that is has the big picture correct, definitely rely on its low level temperature details. But we're thankfully not yet at the point where we can have confidence in its synoptic details.

I'm really stunned to see the NAM so warm for Wednesday night / Thursday. Hoping it's just its usual day 3 synoptic struggles, but it certainly doesn't make me feel good.

Colder. Verbatim was snow for those north of DC for a while, then rain or dry, and then a modest thump of snow again for all.

I came in over 1" a bit south of you, but as pretty as this was, it's been frustrating to watch several bands fall apart on our doorstep.

Agreed, Bob. This one has high-impact potential for a lot of people here, although the 12z Canadian now has a very different solution, so I don't think that the synoptic details are totally locked in yet.

I'm talking about the Thursday-Friday event. Still time to change, but it certainly looks like we will be too warm upstairs for all snow. My point is that the GFS often wipes out the cold air at the surface and turns us to rain, so when I see it maintain the below freezing temps throughout the event and give us a big ice accumulation, the threat is really legit.

When the model that struggles the most with maintaining cold air damming has a solid signal for a long-duration cold air damming event, I definitely take notice.