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1/23-24 Randytastic Snowstorm Part 2 STORM MODE THREAD


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Good trends overnight and so far this morning. This storm looks like an absolute behemoth on satellite too. I think the prospect of "miss" for Rockland/Westchester and south is much, much diminished, and I'd probably go with 10-15" for NYC/LI/up to I-80 in NJ based on the trends overnight and this morning. Where that deform band can sit and the pivoting keeps heavy snow overhead, watch out-that's where someone here can grab 18 or 20". I'm still not ready to say this will be as good for around DC yet for NYC, but the first major part of the battle-getting the heavy snow up to the area, looks to be won. Hopefully the banding acts more like the NAM shows than the GFS. I still think the NAM is too far north and you can see is slowly settling south with how far it gets the heavy snow banding. At least it didn't collapse, which is what I feared it would do after its insane 0z run. 

 

North of I-84, unfortunately it still looks to be too little, too late. South from there to White Plains is the real area to watch to see how far north the real snow can get. 

 

One key to how much you receive is how soon this second low takes over well offshore and starts shutting down the very heavy snow. If it takes over sooner, snow will begin to diminish and also won't make it as far north. That's where models like the GFS (still up to a foot in parts of NYC and Long Island as well as I-78) will be more right. 

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Warmer waters helping out big here. Much like last Sundays snow showers, you can essentially see where the barclinic zone sets up.

I've been doing this for a living for a while now, but these bowling ball ULs rarerly seem to miss southward. Models gave a scare, but I think we're starting to see the reality of how close to 96 this storm could very well be, especially in Philly.

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Good trends overnight and so far this morning. This storm looks like an absolute behemoth on satellite too. I think the prospect of "miss" for Rockland/Westchester and south is much, much diminished, and I'd probably go with 10-15" for NYC/LI/up to I-80 in NJ based on the trends overnight and this morning. Where that deform band can sit and the pivoting keeps heavy snow overhead, watch out-that's where someone here can grab 18 or 20". I'm still not ready to say this will be as good for around DC yet for NYC, but the first major part of the battle-getting the heavy snow up to the area, looks to be won. Hopefully the banding acts more like the NAM shows than the GFS. I still think the NAM is too far north and you can see is slowly settling south with how far it gets the heavy snow banding. At least it didn't collapse, which is what I feared it would do after its insane 0z run. 

 

North of I-84, unfortunately it still looks to be too little, too late. South from there to White Plains is the real area to watch to see how far north the real snow can get. 

 

One key to how much you receive is how soon this second low takes over well offshore and starts shutting down the very heavy snow. If it takes over sooner, snow will begin to diminish and also won't make it as far north. That's where models like the GFS (still up to a foot in parts of NYC and Long Island as well as I-78) will be more right.

Norh of 84 sees warning level snows according to Nam... Pretty far north of 84 actually...

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I am starting to suspect that the series of very strong warm eddies along 38N - they are very, very anomalous for this time of year, some of them have 24-25degC water - is this issue here.  I don't think they're being properly resolved by the globals, and what's happening is that the eddies are being expanded by the resolution b/c they extend over multiple grid spaces.  So the globals see gigantic chunks of  23degC+ water at 38N, and that generates massive convection and pulls the low to where the warmer SSTs are.

 

That's not entirely a false solution, since the warm water is going to draw the low toward where the boundary is, but I think that the globals are overplaying it.  There's also plenty of anomalously warmish water just offshore of LI and south of the Islands - ~10degC water south of Long Island and ~8degC water south of Nantucket.  I think the fine details of SST are going to be relevant here.

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This blows my mind more Than anything... The SREFS are updated, and so VERY well within 12-24hrs.. And no they are not as scewed by the ARW as you may think.. Most NMM members are in board as well..... I'm throwing the challenge on these globals

 

GFS and ECMWF are by their very definition "medium-range" models. They are less useful in the short term. Hence why we have the NAM, SREF, HRRR, RAP, etc. The OP Euro kept the heavy snow west during Juno even after the NAM had bailed. It held out to the end. Even the GFS failed to get the details right during that storm, despite its QPF output being fairly accurate.

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GFS and ECMWF are by their very definition "medium-range" models. They are less useful in the short term. Hence why we have the NAM, SREF, HRRR, RAP, etc. The OP Euro kept the heavy snow west during Juno even after the NAM had bailed. It held out to the end. Even the GFS failed to get the details right during that storm, despite its QPF output being fairly accurate.

Let's not forget the RGEM in that list... let's see how it comes in for 12z. I'd strongly prefer to have it on our side.

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As a non-weather person who's interested in models, I do have this question for you fine folks: Why are the local NOAA offices (both Mt Holly and Upton), with their 9:30 updates to the point/click weather, still saying only about 7-ish inches for my area (Rockaway, Morris County) and 6-ish inches for Mahwah,NJ area even though all these newer model updates are spewing much more than that amount?

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Is anyone else concerned about the fact that the precipitation shield has dropped south 2 runs in a row now? It's fine now but if it continues?  

Going to come down to the banding for us.  If there is a mega band just to our south, we could get stuck in a subsidence zone.  Still think we're good for 4-8 up here with chance for more.

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As a non-weather person who's interested in models, I do have this question for you fine folks: Why are the local NOAA offices (both Mt Holly and Upton), with their 9:30 updates to the point/click weather, still saying only about 7-ish inches for my area (Rockaway, Morris County) and 6-ish inches for Mahwah,NJ area even though all these newer model updates are spewing much more than that amount?

Because making a forecast is not just taking the model with the highest qpf and then taking snow maps verbatim

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As a non-weather person who's interested in models, I do have this question for you fine folks: Why are the local NOAA offices (both Mt Holly and Upton), with their 9:30 updates to the point/click weather, still saying only about 7-ish inches for my area (Rockaway, Morris County) and 6-ish inches for Mahwah,NJ area even though all these newer model updates are spewing much more than that amount?

If the rest of the 12z suite comes in further north then they will up those totals this afternoon, and then again possibly for some areas when we get an idea of where the mesoscale features are setting up. Remember last year a forecast for 2-3 feet busted with 9in at KNYC, that mistake will not be made again. If you're looking for a non moving target forecast, try to reach out to Mitch Volk, he forecasts for NYC's san dept and thus has to provide a non wavering forecast 24 hours out in order for the City to prepare snow removal, etc. resources.

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GFS and ECMWF are by their very definition "medium-range" models. They are less useful in the short term. Hence why we have the NAM, SREF, HRRR, RAP, etc. The OP Euro kept the heavy snow west during Juno even after the NAM had bailed. It held out to the end. Even the GFS failed to get the details right during that storm, despite its QPF output being fairly accurate.

A medium range model is "less useful" in the short term?...........what?

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