OceanStWx

In my experience the NBM is typically too high on snow ratios and too low on max wet bulb temps aloft. So I usually don't like it because I get too much snow in the forecast relative to what I'm expecting. Here the issue seems to be surface temps (NBM has a cap above which it doesn't accumulate snow) and mid level drying. It actually has more QPF than NWS forecasts, so I would guess it's producing a lot of drizzle/freezing drizzle in those 6 hour periods and reducing snowfall as result.

Top 3 American model?

I mean this is how you draw it up in your dreams

SW ME ripping like 2"/hr in the last 3 hours of that run.

Ripping 12-15" in 6 hours. I'll pass on rip and reading that solution.

But reversing the flow at 250 mb is where it's at.

Not singling you out, but I thought this was a good post to highlight for everyone how those probabilities work. Since we have an addiction and track these things routinely at days 5-7+, often times we are discussing a storm before the NWS offices are putting out QPF/snow forecasts. So the probabilities that you are referencing here only captured part of the coming storm. We're required to have 72 hours of QPF/snow, so unless someone intentionally adds extra hours of those variables, our snow probabilities will be partial.

Easy to expand watches, hard to reel them back in. I'm in favor of being conservative on headlines this far out.

Nope. Just here on the swing shift but I tacitly approve the 8-12" jackpot totals as a starting point (or launching pad if you're Kevin).

Euro is definitely a rosier picture, but the GFS does highlight the potential dry slotting issues for a lot of SNE and even coastal ME. Time to put on the big boy forecaster pants.

I always worry about QPF a little at this range. The area of 1"+ rarely ever ends up being as widespread as modeling thinks. I get especially skeptical when the QPF starts tickling 2" over large areas.

The GFS has always struggle with boundary layer temps being too warm, because it had trouble resolving mesoscale details like the coastal front/CAD. As the resolution has improved so have the low level temp forecasts, to a degree. It still wants to bring surface warm fronts through too quickly in the cool season.

Still looks like a -0.5 bias, especially beyond 144 hours to me.

Well it's only been around for one winter so far, but there remains a cold bias so take temp profiles with a grain of salt and know that the actual outcome could likely be warmer.

Time to decommission and move it to Northfield.

We all know WAA has a finite amount of snow it produces, with the real potential being the CCB/deformation banding. The banding signal is definitely there the latter half of Monday into Monday night, but the in between could get ugly outside of any areas of stronger lift.

I could see it working out that way too. Once that first surge of WAA kind of washes out it may really taper off for a large area before the mid levels take over.

Probably too early to start worrying about that, because that would mostly depend on the temp profile at go time.

Yeah the east wind at 250 mb is a great signal for slow moving.

Kim Jong Scoots

Congrats Dendrite!

Certainly, but there is going to be convection with this one. It's rarely handled well by NWP, especially a couple days out. It's definitely not my specialty, but I would hazard a guess that's why we always seem to be seeing subtle (sometimes not so subtle) shifting run to run. These higher resolution NWP systems are very sensitive to convection.

Typically I would like to see the flow be more meridional to do something like that. I like my convection oriented N/S to really drive the heights up.

The Southeast convection is going to play a pretty large role in this, because the ridging ahead of the upper low factors into both the north/south and the east/west position of low pressure. The higher heights ahead of the upper low would suggest a threat for a more west low track.

Really strong banding signal Monday night, but the question I think both on the GFS and Euro is whether it's too far east to really spread the wealth. The AEMATT crowd should love it though.