jm1220

The NAM seems to be the only hi res model this warm (along with its replacement RRFS) so hopefully that’s a good sign. The hi res RGEM was insane at 6z.

We should be monitoring obs down there, if the NAM’s too aggressive with the mid level warmth down there hopefully that bodes well for us.

Was also clear for the last 3-4 days that the I-90 corridor including Boston would get nailed by this storm. Maybe jump on the Acela there and get a hotel for a couple nights.

I’m not sure if these Pivotal 10-1 maps count sleet as snow, if not and there’s 2” more sleet, 5-6” snow would end up as 7-8” accumulation. Even with the NAM that seems to be what we’re looking at. But I agree, definitely can’t discount it.

I mean I could say that the NAM/RRFS are trash and we’re all getting 12-18”, but that’s not reflective of reality. I’d rather set myself up for what to really expect and understand the evolution of it. And it should still be a fun 4-6 hours before going to sleet, and what we get will stay for a long time. Not saying at all this won’t have a significant impact.

I’ve found that these models are too cold with these type storms this far out. By tonight it will have more of a clue. I’m going to look to see trends in how the snow gets here/how fast we pile up vs whether we (around the city) stay snow or change over to much sleet. That to me’s been decided.

I mean look, it’s not like we’re surging into the 40s after this and the snow/ice will be gone. It will be a very dense 6, 8 inches or whatever that will last a long time and over time will congeal into cement. NYC will have the same water content in whatever falls as Albany.

Absolutely, like I said there are differences between this and most SWFEs. If we get clobbered for 5-6 hours before the sleet we’ll all do very well and no one will complain. Last Feb we did well, on the high end of expectations, Nov 2018 is another example and there are others where the snow came in gangbusters. But fundamentally this is a SWFE and the overall setup isn’t favorable for NYC heavy snow. Hopefully we luck out. And 30 miles north of the city, I assume in N Westchester maybe you won’t see much sleet and we dryslot before it comes. But on the low end we have to acknowledge the NAM is a possibility if we get crappy rates/snow growth to start.

I was thinking a couple days ago that this one has similarities locally to that storm.

If you understand the pattern and type of system we have it’s not too difficult to figure out what we’re dealing with. We have a deepening trough too far west and SE ridging, retreating confluence and retreating high. The difference between this and 10000 other lame SWFEs in the past is the big overrunning surface in place and high pressure to provide a wide area of heavy snow before the warm mid levels win out. But eventually it will win out, that was clear 2-3 days ago. It’s a matter of maxing out the snow when the cold air is still there. This is a setup that favors heavy snow along I-90 not here, and eventually every model was going to figure that out. Sucks but we can’t change it. Hopefully we can make more happen with all the cold air we’ll have for the next 10 days, the pattern looks to become more favorable for our type of storm.

Yeah, if there's sleet pushing to I-80 in PA then all the way to Hartford NYC is screwed for any kind of big event. Again it's one possible outcome but the other cold models need to hold on today.

I'd look to maybe N KY, the colder models have places like just south of Louisville with significant snow but the NAM keeps it in OH/IN mainly.

Thanks, I think that's very reasonable and what I'd go with. My guess for my backyard (NW Suffolk County) was 10" and Central Park around 9". I don't see the 12" NWS is predicting here unless we get the very high end to happen.

Yep, it really comes down to the radar presentation in the morning and nature of what's coming at us. I think the fundamentals of the storm are decided-it's a SWFE although much bigger and higher impact nationwide than usual, and there won't be redevelopment in time to stop warm mid level air enough for sleet from getting to 70-80% of us. This isn't one of our heavy snow setups for NYC-we're relying on a huge high pressure dome to provide overrunning and retreating confluence to provide some resistance but those won't be enough. We're making the best hopefully of a lousy storm setup for us in general. If we can make the most of the remaining mid level cold air with heavy steady snow we can get a higher end outcome like the HRRR or hi res RGEM. If it comes in like shredded garbage we'll end up with something like the NAM because all this moisture also will advance the warm air like gangbusters. Whether we like it or not or "vibes we give it" is irrelevant, it's just reality. In the January thread some are pointing out how the pattern should change to one that is more favorable for heavy snow in NYC and we will have cold around for quite some time so even if this one joins the long list of SWFE suckfests, there should be more opportunity and what we get will last for a long time.

I said it's a possible outcome that I'm not taking too seriously yet and the hi-res RGEM is another possible outcome lol.

That outcome might make it a high end advisory event here, maybe we barely scrape it to a warning event with added sleet on top while Boston gets possibly 18". Would go into the long list of SWFEs that suck absolute donkey balls.

I take it as the worst possible outcome and the hi-res RGEM as the best because of the front end thump that still drops 10-12" despite changing most of us over. That said if sleet really makes it to I-84 those of us down here are screwed for anything major and we might struggle to make it to a warning criteria event. We're not there yet but by tonight if the NAM still totally sucks I'll take it more seriously. I didn't like the GFS cutting back at 6z either. NAM has been too aggressive with the warm layer in the past but it will probably be more right than other models close in. We should also monitor obs in the South/TN Valley for how far the warm layer is advancing vs what models have.

The real story from this storm will be the icing down south vs the snow we get here. Austin to San Antonio is expected to get up to about 0.25" ice and there are winter storm warnings all the way to almost Corpus Christi. That would be like us getting 2-3 feet of snow in terms of disruptiveness.

The heavy rates will be key. If those shred up or let up the warm air will advance fast. We saw this in last Feb's SWFE and back in Dec.

Closer to the high pressure/cold source region. I'm confident 80% of us mix at some point. The I-84 crew will probably avoid it-I hope anyway.

Yeah.... much as I would love that it's not going to happen. I think something like the RGEM is the high end for this. I'm not sure if these maps show sleet as snow so the 10-1 snow maps that are lame in general for us, you can probably add up to 2" of sleet on top so if it shows 6" for you, sleet could end up with 8" total.

We're still long range for that model, we're not within 24 hours of most of the event yet, more like 30 hours. If other guidance at 12z trends toward it then sure.

I don't use kuchera maps, 10-1 when in doubt. We could manage a little better than 10:1 since we're starting so cold but ratios will lower as the mid levels warm up.

RGEM still looks really good with a huge front end thump.

HRRR is probably too cold at this range and will come into line with other guidance. I'd love for it to verify too but it's still a little outside of where I'd use it. GFS was always going to cave. NAM getting a little better is somewhat encouraging although losing the GFS to this degree is a little concerning. It's going to sleet a decent amount into the city with this, we just have to hope the heavy snow rates can hold it back as long as possible. SWFEs will just try to screw us over in any way they can and gain the last possible inch north. This is the exact storm type where Boston will get buried.