high risk

For sure. There is a stout low-level inversion which is perfect for getting those loud rolling rumbles.

Very bizarre. The model soundings certainly don't suggest thunder, unless you lift a parcel from up around 700 mb, and that's rarely a path to thunder here.

For snow. Jesus, I'm gonna get fired.

There are many times when the accumulated snow depth product should be examined, but it hates events with marginal temps and big rates like this one.

The details weren't perfect, and it wasn't consistent run-to-run, but some of the NAM Nest runs yesterday did have some handle on the dry slot:

I was mostly speaking in jest, but 1) 10:1 maps are not good for interpreting model snowfall in events like these 2) I'm still troubled by the NAM Nest not showing much here. Maybe it will cave at 00Z, but it has a good track record in events like these at shorter ranges.

Goddamnit, y'all. I have literally worked as a RAP/HRRR developer, and I would still use the JMA or NAVGEM before I used the RAP/HRRR system for snow amounts.

minor addendum: it's still very much experimental and is not scheduled for implementation now until 2025

It's not the kiss of death, but major red flags should always be raised with regards to accepting a 12 km NAM solution when its 3 km nest shows something different.

It always warms my heart to see the snow depth maps posted here, but this is not the type of event for which they do well. They limit accumulation when surface temps and soil are warm, and they'll never capture the ability of heavy rates to overcome marginal thermodynamics. I'd probably either average the 10:1 and snow depth products or mentally adjust the 10:1 maps downward. Kuchera maps might be good too - I hate how generous they are with colder temps, but they seem to properly limit accumulations when the temperature is marginal.

bright banding??

I'll take a few of those convective bursts of snow at the end of the event, please.

I don't think that this is a storm for which the super generous Kuchera ratios will work well. It's not super cold, and lift does not appear to be maximized in the DGZ. With cold ground and temps a few degrees below freezing, this might be one of those cases in which the 10:1 maps actually work pretty well.

One other thing, and perhaps I missed discussion of this: a few CAMs and the GFS show a period of light snow here Thursday evening with the lead wave.

Surface temperatures are super marginal, so it might have some difficulty sticking on roads once we get past 8am or so. That said, the road surfaces should be plenty cold going into the event, so rates might still get the job done.

Nice! I don't have that sort of precision on my station, but it is showing 6 this morning.

The 12 km parent and 3 km nest have different diffusion, so differences in 500 evolution can and do happen.

The northward shift in that run also makes us a bit warmer at the surface, which reduces the ability of the snow to stick during the daytime hours, although surfaces at least will overall be cold.

correction: The actual model run will run on time as it does 99% of the time. The TT graphics processing, run on a 1984 Commodore 64, will be ready by bedtime.

Depends whether they can clear all of the side streets and sidewalks today and give them time to dry out this afternoon before the temps plummet later. Anything that isn't dry will freeze hard tonight, so I would say that there could be delays or closings again tomorrow.

4" here in southern Howard County

Traffic maps across the region look far worse than I expected to see during the daylight hours on a holiday. Likely to look much worse when the sun sets and rates increase.

I agree 100%, and the NAM Nest is that model. It's sometimes a bit too slow in eroding the cold air, but that's better than the GFS and HRRR which wipe it out way too fast.

The NAM struggles with synoptics for sure, but once it figures those out, it's pretty damn good with winter event details. And to be clear, I'm focused on the 3 km NAM Nest, as the 12 km parent is meh. There is no model better than the NAM Nest for resolving cold air damming, and while it sometimes runs too cold in the low levels when sorting out precip details, it's also really good at capturing warm layers that screw up a snow profile. The RRFS has yet to prove competence in these areas, and the HRRR isn't great either, so we will miss the NAM on some days when it's gone.

Correct. It's really tough to generate meaningful spread from a single model core in the short range. And the struggles of the FV3 core aren't helping things.