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March 20th-22nd Suppressed, Fish, Not Coming Threat


Rjay

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3k NAM soundings for my backyard show a warm layer between 750 and 850 for 3 or 4 hours starting around 19z during a period of lighter precip.  I'm not buying it for the most part, but some sleet during any lulls in the precip wouldn't be a shock for central LI.

12k NAM is my hero right now and I am going to ride it into oblivion.

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39 minutes ago, NJwx85 said:

I put a lot of thought into this, final call

Inside the pink line - 1-3"

Inside the light blue line - 2-5"

Inside the dark blue line - 4-8"

Inside the green line - 5-10"

Inside the red line - 6-12"

Locally higher amounts possible in banding. Wouldn't shock me if someone pulled out 18", however confidence is below average on the higher amounts.

sketched_5ab1769a489ca.png

If I were a betting man, I'd wager that you are well underdone on LI. But, I'm certainly not one to judge, and should sleet overperform my expectations that certainly could verify.

personally, I think a general 7-14 inches covers the western 2/3rds of the Island, outside of maybe the immediate south shore... these areas maybe it's more like 4-8 or something...Heaviest totals would be on the grass, with the lower end or maybe even a few inches lower on pavement.

i pulled the NAM soundings from coordinates in NW Suffolk, and, verbatim, there's a 3 hour window between 18-21z where it looks isothermal along the 0C between 875 and 775... a line which is a dangerous line to walk, though the heaviest precip is after this point anyway. that being said, other than that the soundings don't look terribly sleety.

I pulled meteograms from KOKX (which is the old OKX, not Islip) and it showed that the precip was  overwhelmingly snow... how good The algorithm is, I'm not sure but we'll find out.

as I alluded to earlier, my main concern is sleet. Often times models will underdo WAA in the mid levels which does scare me. However, seeing as how the NAM appears to be the warmest aloft combined with the sheer Amount of liquid progged to fall, I think it will overcome those limitations

While I think and hope that your map busts, thanks for the work you put in with your posts, and the effort you put into making maps in the first place. It certainly makes the forums a better place when people put in a bunch of effort

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17 minutes ago, NJwx85 said:

I just think that you're going to have a hard time accumulating in the city, aside from parts of SI and Northern Queens. I guess you could group parts of upper Manhattan and the Bronx in there too.

If temps were 33-34 like the last three storms, I would be going with 1-3" in NYC. I think 3-6" is a good call, because you're going to lose some to melting even with great rates. If everything works out perfectly, then the city could do much better than that, or if the EPS is correct, maybe everyone misses.

It’s already accumulating here although it’s sleet. If it’s freezing or below there won’t be as many problems. 

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19 minutes ago, NJwx85 said:

I just think that you're going to have a hard time accumulating in the city, aside from parts of SI and Northern Queens. I guess you could group parts of upper Manhattan and the Bronx in there too.

If temps were 33-34 like the last three storms, I would be going with 1-3" in NYC. I think 3-6" is a good call, because you're going to lose some to melting even with great rates. If everything works out perfectly, then the city could do much better than that, or if the EPS is correct, maybe everyone misses.

Disagree.  As modeled, snowfall rates of 1" or more per hour will easily exceed NYC melting rates (except maybe streets over subways that are abnormally warm) and once there's a layer of 32F snow, the rest of the snow accumulates easily even at midday, with the high albedo of the snow cover, especially with surface temps below 32F most of the day (indirect solar radiation has little melting effect on newly fallen snow).  Certainly the Park will accumulate easily.  

 

Plotter.php?lat=40.758&lon=-73.986&wfo=OKX&zcode=NYZ072&gset=20&gdiff=10&unit=0&tinfo=EY5&ahour=0&pcmd=11011111111110000000000000000000000000000000000000000000000&lg=en&indu=1!1!1!&dd=&bw=&hrspan=48&pqpfhr=6&psnwhr=6

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6 minutes ago, weatherbear5 said:

i pulled the NAM soundings from coordinates in NW Suffolk, and, verbatim, there's a 3 hour window between 18-21z where it looks isothermal along the 0C between 875 and 775... a line which is a dangerous line to walk, though the heaviest precip is after this point anyway. that being said, other than that the soundings don't look terribly sleety.

 

On the 3k it peaks at +2C around 775mb at 21Z over my head.  SkewT graphically shows a pretty deep above freezing layer for 3 or 4 hours.  From that view, we might also be in a relative dry slot at that time.   On the 12k NAM its all snow.

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