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Potential Snow 11/27 - 11/28


NEG NAO

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If you look at the BL in the 950mb-975mb range, a stronger system is going to increase this flow out of the ENE...the NAM warms this level between 15z and 18z despite the precip increasing because of the ENE flow. The precip intensity is able to fight it off though and it levels out...also the winds start turn more NE in the BL as the system moves east. The RGEM is probably pushing this BL warmth a little more inland.

But it should be watched. This is often the difference between a 35F and rain and 35F with snow falling when 850s are cold enough to snow.

True. Especially since the system is just off to the S and SW as opposed to a coastal bomb which tends to always stay to the southeast of our area.

So, strong coastal systems are definitely better for snow than overrunning waves this time of year for immediate coastal areas -- all else being equal. I still think the models are overdoing the surface "torch" given that evaporational cooling can still put up quite a fight. But it's clear that some ingredients are lacking from what we had during the 11/7 event.

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You can see the WAA surge at the 850mb level, too. SV has the 925mb temperature graphics and you can see the WAA bring the 0c line up to Monmouth County NJ -- and as soundings confirm a little warmer layer below 900mb. But here's the loop for illustrative purposes.

http://www.meteo.psu...4_0z/8loop.html

Also look at how the surface and 850mb wind barbs are perpendicular to the isotherms in southern regions (very efficient warm air advection), but they are about half way between parallel and perpendicular on the cold side. Thus, the warm air advection is "winning".

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Also look at how the surface wind barbs are perpendicular to the isotherms in southern regions (very efficient warm air advection), but they are about half way between parallel and perpendicular on the cold side. Thus, the warm air advection is "winning".

Yeah...this low level warm tongue is the reason why we're seeing the snow algorithms showing little to nothing east of NYC and dramatically less east of EWR. It's evident on soundings, but on this 975mb temperature map you can see the NAM also has the same warm tongue as the RGEM..just a little farther east. The thing that concerns me is that the NAM really likes banding and QPF and can often be too generous in that regard. If it's too strong with the dynamics and lift, it's cooling the column too fast. The RGEM might be more reliable at this juncture.

post-6-0-88154600-1353990181_thumb.gif

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That's a good point regarding the duration of the fetch. It won't traverse very far, but where it does hit would be affected. Immediate north shore beaches would seem to suffer more, intuitively, than the immediate south shore.

...though that seems odd to say. But of course, the hillier north shore regions not along the water will still do better than most locations on Long Island in this setup -- all else being equal.

This does happen in the fall. It was very pronounced last Halloween (nothing within a mile of the sound) but similar happened right next to the sound earlier this month. In another couple of weeks it won't matter much.

However, as you noted with light winds it is really just the beaches that are affected.

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The SUNY model generally rolls out one forecast hour for every real hour that goes by...but is usually slower on nights prior to unsettled weather events.

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UKMET says the GFS is its brother and the NAM is on crack. Maxes out at about 1/3rd inch liquid across central NJ.

You've been hanging around MetFan too long...lol

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I think--as is typical with these events--precip begins sooner than forecast, likely before daybreak. Radar already shows virga beginning to overspread the area.

Maybe it will, but that leading stuff seems to be all virga, and there's quite a gap behind it before the main body of precip. It'll have to fill in.

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