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Thanksgiving Eve SECS/MECS Discussion II


gkrangers

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What a snow bomb that run was....850 was significantly further s/e as well....

Now the question is - is this run of the NAM to be believed ? Have to wait for the rest of the 0Z model runs and see if they trend in the same direction as the 0Z NAM to make that determination..........then after that its time for some NOWCASTING and also some input from the shorter range models..........

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Now the question is - is this run of the NAM to be believed ? Have to wait for the rest of the 0Z model runs and see if they trend in the same direction as the 0Z NAM to make that determination..........then after that its time for some NOWCASTING and also some input from the shorter range models..........

Rgem,ggem,nam,srefs,euro all have good snows in NYC points west...gfs is only skunker

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Now the question is - is this run of the NAM to be believed ? Have to wait for the rest of the 0Z model runs and see if they trend in the same direction as the 0Z NAM to make that determination..........then after that its time for some NOWCASTING and also some input from the shorter range models..........

Nam still warms nyc at 18z or so.

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im not so sure that wind direction is going to hurt the coastal plain so much here...

 

That's not my point...the point is radiational cooling the night before one of these things is not going to play a role in making it colder when the rain or snow moves in.  Its just a shallow, thin layer of cool air near the ground...and one that probably features conditionally stable air...i.e. an inversion or a low level thermal profile that features an increase in temperature with height...and one that is rather easily scoured out once the wind starts to blow. 

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That's not my point...the point is radiational cooling the night before one of these things is not going to play a role in making it colder when the rain or snow moves in. Its just a shallow, thin layer of cool air near the ground...and one that probably features conditionally stable air...i.e. an inversion or an increase in temperature with increased altitude.

True.....I'm sure we've all seen it go from at least the 50s to 30s with snow AND from the teens to upper 30s and rain..it happens so quickly and the airmass that was in place is quickly a part of history

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That's not my point...the point is radiational cooling the night before one of these things is not going to play a role in making it colder when the rain or snow moves in. Its just a shallow, thin layer of cool air near the ground...and one that probably features conditionally stable air...i.e. an inversion or a low level thermal profile that features an increase in temperature with height.

Couldn't be more correct.

A few winters ago west Hampton dropped into the low teens under clear sky's only to rain a few hours later

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That's not my point...the point is radiational cooling the night before one of these things is not going to play a role in making it colder when the rain or snow moves in.  Its just a shallow, thin layer of cool air near the ground...and one that probably features conditionally stable air...i.e. an inversion or a low level thermal profile that features an increase in temperature with height...and one that is rather easily scoured out once the wind starts to blow. 

exactly that is why wind direction in this event is so critical -especailly with a warm November Atlantic-  have to pay attention to hourly observations in this situation and also watch the radars that differentiate between rain and snow to get a general idea which way that line is moving - in other words after the 0Z model runs its NOWCASTING

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This was an *extremely* wet run of the NAM with a huge chunk of heavily populated real estate progged to see 1.5 to 2.0 inches of liquid...if that comes down as snow...as it likely will over the interior...this is a historic November snow event for this part of the country. Tremendous commuting problems can be anticipated on the heaviest travel day of the year. 

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That's not my point...the point is radiational cooling the night before one of these things is not going to play a role in making it colder when the rain or snow moves in.  Its just a shallow, thin layer of cool air near the ground...and one that probably features conditionally stable air...i.e. an inversion or a low level thermal profile that features an increase in temperature with height...and one that is rather easily scoured out once the wind starts to blow. 

good post.   some of this can be ovecome with heavy precip rates, right?  that being said, i think anytime it lightens up the coastap plane is looking at a lot of snizzle.

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This was an *extremely* wet run of the NAM with a huge chunk of heavily populated real estate progged to see 1.5 to 2.0 inches of liquid...if that comes down as snow...as it likely will over the interior...this is a historic November snow event for this part of the country. 

i've seen this move by the NAM before, although I guess some people have been posting that the NAM has not been as bad in this regard recently   Still it always seems like there is one run of the NAM that is a precip bomb during every winter storm.

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That's not my point...the point is radiational cooling the night before one of these things is not going to play a role in making it colder when the rain or snow moves in.  Its just a shallow, thin layer of cool air near the ground...and one that probably features conditionally stable air...i.e. an inversion or a low level thermal profile that features an increase in temperature with height...and one that is rather easily scoured out once the wind starts to blow. 

it certainly doesnt hurt lol.    a little rac is actually beneficial for surface temps after this mild day.

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This was an *extremely* wet run of the NAM with a huge chunk of heavily populated real estate progged to see 1.5 to 2.0 inches of liquid...if that comes down as snow...as it likely will over the interior...this is a historic November snow event for this part of the country. Tremendous commuting problems can be anticipated on the heaviest travel day of the year. 

 

Pretty sure this run cut back on precip. amounts for most people vs 18z (and even 12z), no?

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That's not my point...the point is radiational cooling the night before one of these things is not going to play a role in making it colder when the rain or snow moves in.  Its just a shallow, thin layer of cool air near the ground...and one that probably features conditionally stable air...i.e. an inversion or a low level thermal profile that features an increase in temperature with height...and one that is rather easily scoured out once the wind starts to blow. 

True - would raise the probability of freezing rain under certain circumstances & locations.

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The warm layer is through Long Island by 18z..and straddling NYC...but not at 700mb...now it's at 925mb.

 

There are multiple warm layers and this is a really crappy thermal profile east of the city still. But this run is way better for anyone west of there. 

The storm is almost totally screwed for east of the city and down along coastal NJ-even this colder NAM run is vast majority sleet/rain mix for anyone near the coast. I'll be happy with an inch between the front and end. This one's for west of the city for sure.

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Pretty sure this run cut back on precip. amounts for most people vs 18z (and even 12z), no?

 

When I wrote the post I had not looked at the 12z or 18z runs...and, upon review you make a fair point of comparison...though when I look at these things...my focus is usually on LI & SNE...and that area did look very wet. 

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True, that's another ingredient the NYC folks need in addition to a cold air mass in the proper place.

Well if you look at the GEFS ensembles at 300 hours you see the Aleutian trof coming back. Some of the spaghetti plots show ridging in the EPO and PNA regions...let's hope that continues in future runs.

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