eduggs

Radiational cooling conditions are decent tonight. It's just fake (i.e., low level) cold. Check a sounding. The airmass is warm for January.

Every major midrange model - UK, CMC, EC, ICON, NAVGEM - with the GFS as the only exception, gets snow into or near our region on Saturday. That's 5 days out. It's a tenuous setup for sure, but it's something. I haven't looked at individual ensemble members, but I'd suspect there are a few that drop significant snow for our region.

The 12z CMC, EC, UK, and 18z ICON all get snow to our area or near NW this weekend in the manner I speculated about yesterday. Unfortunately the scenario is less than ideal because the early, initial phase and SLP to Ontario has pushed the initial antecedent cold air far to the NE and we are left waiting for fresh cold to seep in from the W. IMO prospects for some snow have increased since yesterday. I do not believe this scenario is hopeless, although we would need a lot to go right. Inland, elevated areas would be favored and significant snow is unlikely. It would be nice to get the GFS on board, but it trended away at 18z.

The 18z GFS gets a vortmax and 546dm 500mb heights to the FL panhandle with a slightly negatively tilted trof. That should mean potential. The problem is how we get there and the residual 500mb low center in Ontario.

At least the 18z ICON and RGEM don't match the GFS with the clean phase and SLP into Ontario.

The 18z GFS continues with a northern stream shortwave that is too sharp and too closely spaced with the southern wave, which allows wave phasing and a SLP into southern Ontario. This scours the cold air, shunts the baroclinicity offshore behind the front, and taints the 500mb height structure and any follow up coastal.

The 12z CMC shows the coastal low that I believe we need to deliver a miracle for us. It grazes Cape Cod at day 6 and then dumps heavy snow on downeast Maine.

I think the ICON is somewhat close to a longshot scenario that could bring snow to our area or the NW fringes. At day 3 there is one shortwave over CO and another over MN. If they stay longitudinally separated far enough, the more northerly wave can interfere somewhat with the maturation of the southerly wave and shunt any surface reflection further southeast. Wave amplification typically occurs when a shortwave is on the downstream side of a longwave trof. In the ideal scenario, a 3rd follow up wave (upper Midwest at day 4) phases with the southern wave, dropping into the backside of the trof, leading to amplification and negative tilting. If we can avoid an initial wave phasing and resulting SLP into western NY, there may be enough cold air relatively close by to tap into a coastal low. We would still need the trof to take on a significant negative tilt, without pinching off the cold air source, to wrap some moisture back into the cold air. I believe a few ensemble members have shown something like this. But the UK, EC, and GFS are pretty far off.

Yeah the recent model cycles show it cooling down for a day or two around the weekend. But if there are clouds behind the ULL or if guidance switches back to the pinched off ULL that might change. I think it could be a close call for the urban centers.

I'm not rooting against NNE snow. And we would probably all take whatever snow we can get. I just don't agree with the interpretation that the 12z EC is a good snow outcome for anybody outside of Maine considering the potential setup and time of year.

6" in the mountains on a clown map in mid January is not impressive, especially with a high amplitude trof and copious moisture available. Plus many south of NNE flip to heavy rain anyway.

EC and UK are both hideous for anybody outside of Northern Maine.

It looks like there's a small chance some NYC urban areas won't hit freezing all January. I think we'll get a seasonably cold day or two at least, but it's not a given.

CMC is northern stream dominant. That feature has to be way out ahead or flat. Only NNE can cash in with a surface low anywhere near the Lakes.

Detroit - Rochester SLP primary track on the 12z GFS is not what most want.

Keep that primary slp south and east of PA and it's game on for all of NNE and possibly further south. As many have noted, the key is to avoid an early phase.

Definitely not at day 4 in the Midwest. But a subsequent phasing of a follow up polar wave when the main low has traversed further east could work out.

I think what happens days 4-5 with the initial wave interaction and slp track through the midwest is actually more important than where the low center is at day 6.

I think that storm broke the algorithm. 8 day storm? Pretty generous 4" coverage on the southern periphery. Getting the NYC to Trenton corridor in that areal coverage also probably helps the score. I guess technically a T is < 4"

Actually I would say there is a potential cold source to our north on Thursday. But the early wave phasing and slp through the midwest pushes it out of the northeast and deep into Canada.

The amplifying and severely negatively tilting trof that's modeled is fun to look at. There's actually a little cold air to our north to work with initially, and this is still 6 days out. So I keep checking too. Problem is all guidance is showing a relatively early phase in the midwest, which quickly scours out the cold throughout the northeast. That means even if a developing coastal slp goes ballistic, there's no available source nearby to tap into. We need to hope for a re-jumbling of the features that shakes out more favorably. 1st goal is to lock in more cold air.

The 0z CMC and even EC are incredible. Days and days of rain beginning next weekend. Presumably coastal flooding too. Most northeast ski areas would probably have to shut down. Peak winter climo season.

I think we need a snowstorm modeled inside 3 days, not a "pattern." To the degree that patterns can even be defined, they are continental to hemispheric in scale. Snowstorms are local to regional.

The Dunning-Kruger effect neatly illustrates so much of what we observe both in life and on this board.

Careful about using those 10+ day ensembles. Any "signal" that you see out in that range should be treated with skepticism. It's fine to interpret what current model guidance is showing. But it should be well understood that those features have a good likelihood of verifying significantly differently than currently modeled.