jm1220

Looks lame/warm again like 12z. If we’re punching sleet up to I-84 here, people near the coast might barely eke out a warning event. Hopefully tonight 0z we resolve this one way or another, if not we watch the radar in the morning to see how the snow advances in. That’s really the difference maker here.

Shoulda woulda coulda?

Winters for the last 20 years in Central PA have by and large been horrendous. I’m glad that most of that region should do well tomorrow but the long term average for State College, Altoona, Williamsport etc is over 40” snow per winter. They’ve been able to manage that in their few high end winters in the last 20 years but by and large way below that. Way too many SWFE’s that turn into sleetfests, cutters or Miller Bs that develop too late, much fewer Miller A coastal huggers like 3/1993 or storms that would redevelop offshore in time-now these are good I-90 snowmakers not I-80. It started right when I went to school there and never really improved. So I’d say there’s definitely some long term shift that’s screwed them over and not some short term correction that will easily reverse.

Hopefully tonight's 00z gets better, then I'll start to legit worry it's onto something. I consider this the low end and RGEM the high end if all goes perfectly. This run looked maybe a hair better but all in all still sucks. Tough forecast for NYC because it's really a couple hour difference and intensity of the initial snow.

Looked maybe a touch warmer to me. Sleet gets here by 22z roughly.

Unfortunately with the late developing coastal, you have easterly winds for a while which warm up the surface.

The posters from coastal NJ south of maybe Asbury Park yes since there's an easterly flow established, otherwise no.

Would just make it a gigantic glacier. Even if we have a period of freezing drizzle at the end it will fuse everything together into concrete.

I’m thinking 8-10” total where we are, have to hedge lower with the NAM as crappy as it is and GFS cutting back. Hopefully the snowy models have a clue.

We did pretty well last Feb with that smaller SWFE when the snow came in heavy right away. Same with Nov 2018 which was completely unexpected. This will have a larger overrunning surface which means theoretically a longer duration of snow. But we really have to see how this evolves overnight/in the morning. We’ll do well if we have heavy snow echos coming in like a wall for hundreds of miles to the south. If we have spotty in some places heavy snow in some places light and dry holes thrown in, we won’t. And the sleet will take over sooner.

Yep, 2/13/14 for example I don’t think was a rapidly intensifying coastal and there was widespread 10-14” amounts.

It’s not going to rain on LI (plain rain) outside of maybe Montauk. This kind of cold surface air won’t be dislodged unless we had a strong prolonged onshore flow. I could maybe see freezing rain for a time but the back half of this storm is probably sleet. NJ gets that prolonged onshore flow so south of Tom’s River it might really change to rain.

Hopefully the ratios start out above 10-1 when the column is still cold, so maybe we average out 10-1 before the sleet comes in. Some places north and west that stay all snow will likely average 15:1 type ratios given the amount of moisture in the snow growth zone and lift.

I’m not sure of the exact algorithm but it’s supposed to print out predictions based on analysis of similar storms in the past and gain experience and therefore better predictions in the future based on verifications. I’m sure it would evaluate similar patterns at 500mb, analogs etc to come up with the predictions. I’m not sure how it directly evaluates current atmospheric conditions to come up with the predictions but it seems to match up pretty well with the operational EC.

Well-it either scores a coup here or falls flat on its face. It’s supposed to build better results with experience-not sure how much it has with setups like these. It did pretty well with the Dec storms.

NYC only had 7-8 inches from 3/14/17 but there were snow/ice mountains everywhere and streets were horrible as if way over a foot fell. I remember how bad it was driving down some side streets in Queens. The 7-8” NYC had was the same water content as someone in PA that got 20”+. This one won’t have the same water content (I think over 2” liquid) as that storm but it will still be significant impact.

Exactly. 7-8” of combined snow and sleet will be a PITA to move to put it mildly. And that seems to be the low end.

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.