high risk

FWIW, one of the findings during the GFSv16 evaluation was that it handled cold air damming better than v15, possibly due to having more vertical levels. It still won't be nearly as good as the NAM nest, which in my opinion handles damming the best of the models (and sometimes even overdoes it), but once synoptic disagreement is removed, I'd favor the v16 profiles over v15.

done! NAM3 in particular looks much better for later Saturday afternoon.

That's a good catch. It's not as blatant on the NAM3 and the Hi-Res Windows, but even the older cycles of those models clearly show a bit of a southerly component to the winds tomorrow that is absent in the 12z cycle.

12z guidance pretty much all took a pretty big step back in terms of coverage of convective rain/snow/graupel showers Saturday afternoon. It's not obvious why, but they all seemed to pick up on *something* that's hostile to the potential.

You're too kind. Easy to make a call on this when you have a strong upper trough axis swinging through with lapse rates like these:

Nice signal in the NAM nest for some heavy rain/snow/grapuel showers later Saturday as the trough axis swings through with steep lapse rates.

I don't have enough fingers to count the number of dead-wrong statements in this post.

There are two machines: one in Orlando and one in Reston. One of them is the production machine, and one is the development machine, but they switch back and forth.

https://www.emc.ncep.noaa.gov/users/meg/gfsv16/realtime/gfsximages.html It looks like the original post was indeed referring to an older run, but the latest run does have a coastal around the 4th (although it's not a snowstorm, verbatim.)

Yep. Big upgrade in early December. https://www.emc.ncep.noaa.gov/users/meg/rapv5_hrrrv4/

Yeah, that's fair. It just feels like LWX likes to warn on these things a lot, and the false alarm rate is super high. For this event, I'd rather wait for a report to come in before pulling the trigger, although it's easy for me to say that without my neck on the line.

I'm struggling to understand the severe warning, as while that's an impressive feature on radar, it shouldn't be surface-based and therefore unable to get the winds to the ground. But I'm prepared to be wrong....

Definitely thunder. We had a severe thunderstorm watch that afternoon.

I lost track trying to count the number of incorrect details in this post.

While it's a bit unclear how much precip will linger immediately behind the front (for a brief period of sleet or snow early Christmas morning in the DC metro area), there may be more hope for a period of snow showers during Christmas Day as the upper trough axis swings through, and low-level lapse rates steepen. There is a very weak signal in the NAM nest, but there is a smack-you-in-the-face-with-a-small-snowball signal in the 18z HRRR.