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2/20 -2/22 Storm Threat Discussion


Zelocita Weather

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Its a bizarre setup in that the confluence increases as you go east so very much like Warren county NJ saw more snow than JFK on 2/6/10 this is an event where it may rain in Erie PA but be all snow in N NJ. ...that said this has major bust potential if leading into the event the models still are showing the same thing as this run of the NAM is because even a 50 mile shift and someone forecast to get 5 inches will get squadoosh.

Ah, this is why I saw some people in the New England subforum saying that SE Mass might actually do well with more cold air banked to the east. Might this be the case for our area also?

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Current air temps sort of reflect how the colder air may be slightly more deeply entrenched over eastern sections of the CWA...Newark is 29 F but Montauk is already down to 23 F...and obviously no radiational cooling is going on...

How cold are they now? Its 23 here.

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But it also likes the GFS went slightly north at 0z for the 2nd wave so that if verified, we might get a few flurries or even a little light snow from it. Lol.

So we have a few options on the table since the fates of the two waves seem intertwined.

A. Get Wave 1 to trend south, so more snow, but Wave 2 becomes crushed and we get nothing from it.

B. Get Wave 2 to trend north, which means more rain, but then Wave 2 can amplify more and we get snow from that.

C. The worst case scenario and the two waves both miss the area or we only get very light accumulations from one, or the other or both.

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So we have a few options on the table since the fates of the two waves seem intertwined.

A. Get Wave 1 to trend south, so more snow, but Wave 2 becomes crushed and we get nothing from it.

B. Get Wave 2 to trend north, which means more rain, but then Wave 2 can amplify more and we get snow from that.

C. The worst case scenario and the two waves both miss the area or we only get very light accumulations from one, or the other or both.

I'll take option D.

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Get hit by both? I dont know if thats possible lol.

You got it, LOL. But I know that's not realistic.

Actually as recently as yesterday I was rooting more for wave 2. More potential to be significant for north-central Jersey to NYC area because colder temps will be in place. Snow ratios. But of course now it's more likely that wave 1 will give us a bit of accumulating snow, while wave 2 gets squashed to the south. I'll be happy if we can squeeze out a couple inches tomorrow night. North of the city obviously will do a lot better.

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You got it, LOL. But I know that's not realistic.

Actually as recently as yesterday I was rooting more for wave 2. More potential to be significant for north-central Jersey to NYC area because colder temps will be in place. Snow ratios. But of course now it's more likely that wave 1 will give us a bit of accumulating snow, while wave 2 gets squashed to the south. I'll be happy if we can squeeze out a couple inches tomorrow night. North of the city obviously will do a lot better.

I was rooting for #2 also, higher ratios and much less chance of mixing. Now Im wondering if #2 will be much drier, because it looks like the areas that will get hit "hard" by it, wont be getting anything more than light accumulations.

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The GFS tend tom predict the lightest isohyet too far north often. However, NYC should see 2-6 inches from the first wave.

An infamous case of this was last year, 2/6/10 when according to the GFS we were going to get a nice snowfall. It had the cut off about 25-50 miles too far north.

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0z GGEM looks like a decent hit for the area with the 1st wave. The 2nd wave is slightly north of the previous run. It now has light snow getting into NYC.

Ukie also appears decent. Ggem, Ukie, nam and Srefs look fairly similar. 2"-4" event with spots of 3"-5".

Gfs is an outlier it appears.

Hope the euro stays cold.

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You got it, LOL. But I know that's not realistic.

Actually as recently as yesterday I was rooting more for wave 2. More potential to be significant for north-central Jersey to NYC area because colder temps will be in place. Snow ratios. But of course now it's more likely that wave 1 will give us a bit of accumulating snow, while wave 2 gets squashed to the south. I'll be happy if we can squeeze out a couple inches tomorrow night. North of the city obviously will do a lot better.

If we somehow did get accumulating snow from both, it would complete the Feb 1994 analogy. That month, the second wave was supposed to be suppressed to our south too (and the first was supposed to change over), well the first didnt change over until near the end of the event and the second one came much further north than it was originally forecast to. They both became nowcasting events.

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The GFS tends to predict the lightest isohyet too far north often. However, NYC should see 2-5 inches from the first wave.

Yea, which is why when you see a storm coming up from the SE and a monster high to our N, the NAM will own the GFS for the northern fringe of the qpf. The GFS loves to bring light qpf into high pressure for whatever reason. In this case, I do like the 1st wave more than the 2nd so i agree with you there. With the mild air south of the boundary, the gfs is firing convection due to feedback and that is the issue i see on the last 2 runs. It wasn't doing that previously from what i recall.

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Yea, which is why when you see a storm coming up from the SE and a monster high to our N, the NAM will own the GFS for the northern fringe of the qpf. The GFS loves to bring light qpf into high pressure for whatever reason. In this case, I do like the 1st wave more than the 2nd so i agree with you there. With the mild air south of the boundary, the gfs is firing convection due to feedback and that is the issue i see on the last 2 runs. It wasn't doing that previously from what i recall.

The GFS seems very quick with the 2nd wave compared to the other 00Z models so far....at the same time the GFS is often too north the NAM sometimes is too smoothed or sharp with its gradient...this is a scenario though where a sharp cutoff would likely be right but the NAM often has a very sharp cutoff on the NW side...say a 50 miles gradient between 0.10 and 0.50 when that gradient may verify at 100 miles....the NGM was the worst model at overdoing precipitation into cold air...the 2/24/89 bust was a classic example of that....the 1st wave on this remains a very edgy deal though, it reminds me alot of 1/13/00 and the 2002 pre-thanksgiving storm where we dealt with similar scenarios with NYC being on the southern fringe of the snow on models and wound up with nothing as the storm tracked 50 miles north...this time we have the confluence on our side so it may work out.

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The GFS seems very quick with the 2nd wave compared to the other 00Z models so far....at the same time the GFS is often too north the NAM sometimes is too smoothed or sharp with its gradient...this is a scenario though where a sharp cutoff would likely be right but the NAM often has a very sharp cutoff on the NW side...say a 50 miles gradient between 0.10 and 0.50 when that gradient may verify at 100 miles....the NGM was the worst model at overdoing precipitation into cold air...the 2/24/89 bust was a classic example of that....the 1st wave on this remains a very edgy deal though, it reminds me alot of 1/13/00 and the 2002 pre-thanksgiving storm where we dealt with similar scenarios with NYC being on the southern fringe of the snow on models and wound up with nothing as the storm tracked 50 miles north...this time we have the confluence on our side so it may work out.

well, the example i gave was different than this of course. I think it will fall somewhere in between. The NAM is too inconsistent for my taste. The source i use for isentropic maps is still updating and i didnt see the 12z data today. but yesterday when i forecasted, the 12z gfs had pretty good isentropic lift on the 300k surface and it's fast qpf idea seemed plausible.

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Does it look like warning criteria snow for NYC and LI with the latest models and ensembles? Do you think south shore LI can also get 6 inches ? Looks like one inch per hour snows from 5AM till noon, with excellent snowgrowth and 10-15 UVV 700 mb level. We should go from flurries to 1/4 +SN that lasts for 4-6 hours and taper to sleet drizzle mix around noon with event cutting off. Second event looks like flurries to light snow in the evening. If event could go 75 miles further north we could have 5-9 inch snowfall Monday night with 15 to 1 ratios with perfect set up for powder. Can it happen like in 94 ?

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I understand your concerns about the southern fringe of the snow missing NYC, but I think the chances of the 1st wave going north of NYC are minimal. I would expect a track across SE PA and off the central or southern NJ coast.

I still think the heaviest snow will be a bit north of NYC, however - from around Orange/Rockland County NY ESE to Fairfield County CT and eastern LI.

The GFS seems very quick with the 2nd wave compared to the other 00Z models so far....at the same time the GFS is often too north the NAM sometimes is too smoothed or sharp with its gradient...this is a scenario though where a sharp cutoff would likely be right but the NAM often has a very sharp cutoff on the NW side...say a 50 miles gradient between 0.10 and 0.50 when that gradient may verify at 100 miles....the NGM was the worst model at overdoing precipitation into cold air...the 2/24/89 bust was a classic example of that....the 1st wave on this remains a very edgy deal though, it reminds me alot of 1/13/00 and the 2002 pre-thanksgiving storm where we dealt with similar scenarios with NYC being on the southern fringe of the snow on models and wound up with nothing as the storm tracked 50 miles north...this time we have the confluence on our side so it may work out.

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