jm1220

These would be 2/1/21 like totals at least for the city and LI. Much as I think this will be an impressive storm here I don’t see that kind of an outcome at least here.

Maybe we get a compromise of some type since the amped models seem to be relaxing a bit. But it would take a lot for me to buy into a SWFE type system dumping widespread 12”+ in NYC. Would I buy that in Boston-sure.

I wouldn’t go higher than 8-12” for NYC/LI/I-78 to I-80 right now because of uncertainty and models like the RGEM. It’s possible the GFS is right but it’s wiser to hedge toward how SWFEs usually are which is they try to amp and trend north unless there’s the brick confluence wall to stop them, and sneaky warm layers that try to move in quicker than expected. But the GFS is another possibility if we can catch a break with a further south transfer and decent coastal development, in which case those 12-18” amounts really can happen. North of the city especially I-84 corridor I think is a lock for 12”+. We’re lucky this is a SWFE setup where it’s running into a huge overrunning dome/high pressure which means even the amped models dump 6-8” before changing over and again-the sleet will definitely have its own impact and thicken up the snow pack.

Oh I agree.

I’m glad that the “low end” RGEM still gets us with 6-8” at 10-1 with the overrunning surge and we have the high end GFS/UKMET with 12”+.

It transfers it earlier/further south which keeps the mid level warm air away. And puts us in a pivot zone where we don’t dry slot and the coastal snow takes over. That’s another consequence of a primary driving into Buffalo-the 700mb layer dries out and we get the dry slot. GFS has been consistent I’ll give it that.

If we can manage 1” liquid as snow then I’m pretty confident we can manage 12”, I think the NWS amounts are a little high. If something like the RGEM happens then sleet probably would cut into the accums a decent amount in the city/LI and up to the CT coast. Still time for trends in either direction with this one and if this is more of a SWFE it will try to get as far north as it can. We want a sloppy phase and stronger confluence.

You’re near Tom’s River right? You’ll get the initial overrunning snow burst the rest of us get so you should do well too.

I think it’s a little high as well but if higher ratios work out it’s possible. In any case the north bumps seem to have stopped so that’s good.

I agree. I remember the huge snow mounds in the city after the 3/14/17 storm even though a huge amount was sleet. Sleet has a disproportionately high impact for how much of it falls-1” of sleet is the same water content as 3-4” of snow and it tends to stick around a lot longer. I’d rather it snow all things considered but anyone who wants deep long lasting snowpack shouldn’t complain about some sleet thrown in after a big thump of snow.

This reminds me of the 12/17/20 storm overall-SWFE type system that transfers to a coastal system. 8” here from that one.

There’s like a 60 knot jet coming from the Gulf. There will definitely be a warm mid level layer and sleet in a wide area. It’s coming into a big high pressure area which causes the huge area of snow out ahead but it eventually becomes too much of a good thing. But sleet in the end is a plus if it freezes into the snow and turns it into concrete. This stuff won’t be going anywhere until we get a major torch.

If we get 2”/hour rates for 5 hours we know what that can add up to. This seems like the type of SWFE that can produce- heavy snow shield coming into a strong high pressure that provides an overrunning surface.

12/17/20 might be a pretty good one at the end. Hopefully the snow comes in better than that one did-I ended up with 8” but was hoping for 12+ but the snow shield broke up so the warm mid level air advanced faster.

Yep, seen it before too where if 750-800mb are wrecked by the initial primary lows hanging on too long it can take a while to flip back to snow. But the coastal storm evolution is the complex part of this that we have to wait and see on. It’s looking good for at least 4-6 hours or so of heavy snow before any warm mid level air arrives.

I think there’s an in house model group the NWS uses for this but someone with more information can add further.

We all know the tendency for these to trend north over time.

If we get 10” of snow with sleet mixed in at the end that will all freeze up and thicken the snowpack up, count that as a big win. Rather that than 15” all snow that melts faster.

We’re still not in a regime that allows for big coastal storms like before 2020. Still very progressive and favoring fast moving/suppressed or SWFE type systems. If this one trends to a SWFE type system although one that’s much larger and more far reaching than usual it would fit the mold.

It’s really not overly complicated, if we have a strong 700/850 low go NW of us, we will mix eventually-plain and simple. That means the winds at those levels are from the south and a warm direction. It doesn’t matter that the surface is cold. We could have a lot of snow fall before then but the same mechanism driving all the moisture from the Gulf also brings warm air. If the snow comes in like a wall it helps hold the warm mid level air back and we can pile it up quickly, if it comes in like shredded garbage it will disappoint and we get sleet sooner. We could also dry slot before or as that warm air arrives since dry air will pivot around the mid level lows from the south. We need the mid level confluence to force a further south transfer. If se see that retreating we have a typical SWFE setup. There’s the other possibility of a coastal system bringing snow back in but I think that won’t be determined until we’re closer in.

Definitely a positive with this storm that there seems to be a floor of at least a decent event with the initial overrunning surge and potential for something really great if we can get this coastal to crank in time.

Oh sure, if this stays intact it looks good for a few hours at least of couple inch per hour rates. That's a thumper if I ever saw it, and tons of moisture coming into the overrunning dome.

Yep I’ve seen it before where it’s been 10 degrees outside and we get tiny needle and sand flakes.

That would make sense, if we start out with good saturation and lift in the -12 to -18C cloud layer we get the best ratios from good snow growth. If that warms up we lose the best ratios. 20:1 is very rare even in the best setups and I’d argue we wouldn’t even want that as that would be pure fluff that would compact/blow away. I’m fine with less snow overall but longer lasting.