Updated Final Call Snow Map, Observations Thread 2/21-2/22

[Frank_Wx]

Updated my final call snow map based on latest observations / guidance runs.



I went colder for the majority of the area and shifted the jackpot zone further south and east. Precipitation is moving in at a rapid rate this morning which means the more cold air we have to work with and less warm air we have to deal with (since there will not be as much precip. left to fall). Additionally, guidance is keying in on shifting the baroclinic zone further south and east as well. Areas just north or west of this zone will experience the greatest frontogenesis. Snowfall rates will be in the order of 1"-2" an hour. I do expect a changeover to ice and rain around NYC Metro still, but like I said, the amounts of precip that will be left probably won't be a lot. Coastal NJ and SNJ can expect a little more rain, hence the lower amounts.

**Isolated areas near the red jackpot zone that are in blue could see amounts greater than 6" as well.**

Should be an interesting storm to nowcast.

It looks healthy

http://www.intellicast.com/Local/WxMap.aspx

[mmanisca]

Good call Frank. I noticed the colder air hanging a lot tougher than originally forecasted by the models and kind of figured by most of us to happen!

[sroc4]

This comment was made on the 18th by Larry Cosgrove. This was when the LP was a strong GLC soln:
The latest model trends have a contiguous system which crosses middle Appalachia into PA and NJ. I account for snow cover, depth of cold air, and the fact that, for all of the warm air advecting north along the backside of the surface high, the push of warmer air gets subverted by the surge of Arctic values. Remember that cold air always wins out over warmth when a westerly component is noted with 500MB winds. So I see a changeover scenario whereas others may only be looking at rain.


So if you look at the current mesoscale analysis at 850mb you can see the flood gates are open for business to the GOM; the blue indicates the freezing line:
http://earth.nullschool.net/#current/wind/isobaric/850hPa/overlay=temp/orthographic=-87.32,35.91,2048

But as the comment states above 500mb is westerly:
http://earth.nullschool.net/#current/wind/isobaric/500hPa/overlay=temp/orthographic=-82.69,37.64,2048


The point here is that it is going to be a positive now cast for many on this board...I think...esp for my friends N and W.

[Frank_Wx]

[Frank_Wx]

This comment was made on the 18th by Larry Cosgrove.  This was when the LP was a strong GLC soln:  
The latest model trends have a contiguous system which crosses middle Appalachia into PA and NJ. I account for snow cover, depth of cold air, and the fact that, for all of the warm air advecting north along the backside of the surface high, the push of warmer air gets subverted by the surge of Arctic values. Remember that cold air always wins out over warmth when a westerly component is noted with 500MB winds. So I see a changeover scenario whereas others may only be looking at rain.


So if you look at the current mesoscale analysis at 850mb you can see the flood gates are open for business to the GOM; the blue indicates the freezing line:
http://earth.nullschool.net/#current/wind/isobaric/850hPa/overlay=temp/orthographic=-87.32,35.91,2048

But as the comment states above 500mb is westerly:
http://earth.nullschool.net/#current/wind/isobaric/500hPa/overlay=temp/orthographic=-82.69,37.64,2048


The point here is that it is going to be a positive now cast for many on this board...I think...esp for my friends N and W.

An excellent post. By you and LC.

[Frank_Wx]

[lglickman1]

Did something change overnight that made upton change their snow amounts?

[Dunnzoo]

Looking at the soundings on the 06z gfs and nam for NYC, the columns are cold all afternoon, however between 9-midnight, there is a small rise in temps that would indicate freezing rain since the surface is still cold. Being NW of the city, I'm hoping we stay all snow. Both models show me at a total of about .5" liquid.

[Frank_Wx]

One band just formed over central PA

[HeresL]

Did something change overnight that made upton change their snow amounts?

I'm confused as well. Upton had me in 6-8 last night but down to 4-6 this morning...

[Quietace]

Still only 9.9 degrees...wow

[algae888]

this is what we need to watch today as 540 stays south off most of the region as do 850"s. this is 925's as of 745am.hard to tell from this map but 0*c over west Virginia right now. need towatch how this layer progresses today.

[algae888]

the last blue dotted contour line over s/w west verginia is 0*c line. bottom center of page

[Quietace]

Hrrr has area start snowing between 12 and 1...with temps between 25-30 degrees, lower in HV and PA.

[snow247]

Morning all, radar looks great! Fun day/night incoming.

[oldtimer]

14* High clouds calm

[algae888]

also if you look at map I posted above western Virginia is -9*c and western west Virginia is 0*c. look at how tight those lines are. this is where best lifting is occurring and matches well with heavier radar returns.

[Quietace]

HRRR has R/S line making a northward push into area by 2z Sunday. By 3z south of I-195 is Raining

[Frank_Wx]

*whistles*

[skinsfan1177]

Hey Ace is this a close call as far as rain snow line or no

[rb924119]

In looking at the radar, is anybody else concerned that this is moving too much west to east?

[docstox12]

Maybe all this heavy cold air is suppressing it right now.

[mancave25]

To me it looks like it pivoting ne

[snow247]

12* here

[algae888]

look at what nam did with snowfall from 00z to 6z. any concerns?

6z

00z

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