eduggs

I agree strongly with everything written except this. I believe these features are not causally connected. They are only loosely correlated, and always in hindsight. Besides that, the trof IS clearly sufficiently sharp for a major event. But the synoptic details (which you correctly mention) impede development in a way that would impact us locally.

Don, if you go with uncertainty analysis or probabilistic analysis, then I think we're on the same page. But not sensitivity analysis. Early in most months it should be close to a coin flip whether the month will end up above or below normal. Our climatic base state relative to previous decades is warm, so we hedge warm to start. And then Bayesian updating based on long-range modeling.

Snow is good anytime, but February is melt season and often the beginning of mud season. December- and January snow is more emotionally and aesthetically valuable at our latitude.

The hype started based on long-range anomaly charts about a week ago. A favorable "look" on those charts is like cat-nip to some people. The ICON, then GFS, and eventually ECM gave credence to this hype for a while.

The GFS and GEFS have performed poorly for our local area for the past few wintry potential threats. I know local performance is highly variable and somewhat random, and I haven't seen updated verification scores, but I do wonder if the brain drain that started at NOAA/NCEP around 2016 might be finally catching up to us.

That 55% prediction is not very useful without the associated uncertainty. Even if the statistical method used for the sensitivity analysis is sound, there is presumably a large spread considering our lat/lon and the variability of the underlying factors/predictors. It could plausibly end up well above or well below normal for the month.

The GEFS are clustering around the OP as usual, so 0z is worse than 18z. But they are not catastrophic. They don't look completely hopeless. Still some plausible path back to a snow threat. When you trace the critical shortwave(s) back to deep northern Canada, its seems incredible that such a minor shift (100 miles) in placement of a ripple in the flow that travels 3000 miles could have such a major impact on future weather. That's just to say that a minor model error in the critical shortwave track could still cause significant model changes from here on out.

It feels like it's been a pretty active winter so far in the Adirondacks and N VT. Lots of small and medium events. I see no reason why that won't continue. Down here we've had a lot of dustings and coatings... As many this year as the past 4 combined.

I don't think it's game set match just yet. It's not unprecedented for a 3 or 4 day model head fake. But we'd really have to pull a rabbit out of our hats at this point. If this plays out close to the 0z GFS, I think it was a great job by the AI models. They showed this weird, disjointed surface setup for days and hardly wavered.

Yeah the GFS shifted towards model consensus unfortunately.

The critical shortwave on the 0z GFS is slightly further east this run. Crossing WI instead of MN. That's probably not good.

The Canadian is still not on board.

It finally has the critical shortwave diving south through MN at 60hr. Not quite as sharp as the GFS, but huge improvement over 18z.

I did notice a bunch of 960s something mb lows on the individuals off of the Cape at 18z Fri. That's a bit west of the GFS op. I'll take the 958mb just off Montauk though! It's fun to look at but even on the GFS and GEFS, the 850mb/700mb lows are too slow to develop. And I'm losing confidence in this type of solution as we lose models to the Canadian solution.

It's a shame that all the overrunning is modeled up in NW PA and NNY. If the GFS is right, there could be some good snow with that feature.

We lost the UK, ICON, and ECM-AI today. We'll track it to the end like the Challenger crew steered the shuttle, but this is starting to look cooked.

We're down to the GFS & GEFS. We'll see how the ECM and UK look. This sort of has the feel of a glimpse of a chance slipping away.

It's not great to have the key shortwave missing or in an unfavorable location on the ICON and GDPS... and also the short range NAM and RDPS. Even by 72 hours it's clearly missing... that's approaching short term modeling range.

GEFS finally support the op and the UK is hugely improved. Yes precipitation is lacking across all guidance relative to the mid-levels. Is that a function of meager lift and lack of overrunning or will it beef up as we get closer?... If I had to guess right now based on the GFS/ICON/UK general evolution, I would expect locally heavier QPF but a lack of a widespread precipitation shield. In other words, I think the lack of classic overrunning out ahead of a surface low decreases the overall magnitude of QPF that we would normally expect with a strong system... but locally, deformation is probably being undermodeled at this stage by the global models.

GFS-AI is a little worse again. It looks like we're still firmly in a wait and see mode. Still really big intermodel and intramodel (ensemble) variability. Huge spread for 4.5 days out. Way too few big QPF solutions for my liking.

It's interesting how different the CMC is from the GFS and ICON. The CMC completely lacks the intense follow up shortwave that drops from MN to TN and explosively amplifies the trof. On the Canadian the shortwave and its vorticity is closer to the Lakes and connected to the PV. It this feature on the GFS isn't real, the exotic solutions disappear. Heck even with the GFS evolution we get fringed. I love tracking these types of potential events for the excitement and drama, but they usually don't produce widespread snow.

The ICON is still too neutrally tilted. The best PVA is well offshore. We'd want to see vorticity wrapping all the way around the mid-level low towards the coast like the 12z GFS. Otherwise the SLP will track east and away from us.

With the possible exception of the GFS (esp 12z), the solutions depicted are primarily deformation precipitation with little or no overrunning frozen precipitation. This makes it more difficult to get a high QPF event. This partly explains the low snow means on the ensembles and AIs. It's only when the solution is extreme (12z GFS) that the big QPF appears.

The ULL in interior Quebec is more of an impediment to trof amplification than the shortwave near North Dakota IMO.

Looked like a clear improvement to me. Several runs in a row now. But the GFS-AI went the opposite direction. With the ICON also worse, it's kind of a wash. Theoretical high end potential but so many failure modes.