jm1220

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.

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.