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Winter storm 12/8-9 Observations/Nowcasting II


nj2va

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So I went back and looked and a few thing stand out, but really nothing to think 8-9". Here is 00z last night. Notice the strong lift progged at 700mb. That is a red flag. However notice the 850-500 RH and VV progs. Not as pronounced through this level and too warm (classic GFS) but there is a hint at good lift through a saturated layer. Also notice 700mb winds. Notice the strong 700mb jet pushing into DC. That is helping with the frontogenesis...you have convergence with a stronger H7 jet pushing in. Notice also the good 850mb LLJ is way south. This is more classic mid level fronto and not necessarily LLJ convergence at 850mb. Also notice the nice thermal ribbon at this level. This is certainly a strong gradient at H7 which will cause the atmosphere to induce a frontogenic circulatio to restore thermal balance. Also notice a good H3 jet. This is a decent entrance region of the jet and virtually all the fun happens at the entrance region of jet streaks in the winter. The reason is that the divergence at the entrance region will help to allow the low level jet to rise in an isentropic fashion to fill the void left by divergence at 300mb. 

 

Now look at the prog today from the 12z GFS valid at 15z. aqnd 18z. Much colder and more robust with the 850-500mb lift.

 

 

 

 

 

 

 

 

 

12z today.

 

 

 

 

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One more degree and I can chuckle at those mountain valleys.

 

Most of the time I hate where I live because I am so damn close to the Potomac and relatively mild conditions.

 

This time tho I am exuberantly happy. A half inch or more of ice is no fun at all, especially on powerlines and on tree limbs.

 

I might rise above freezing well before midnight. I am so happy about it I want to shout it from the housetops :)

 

The cleared road has good water reflectivity, meaning that it is only wet, no ice at all on the road by my house. Ice and slush look very different. This is the reflectivity of the road from rain in the summer.

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One more degree and I can chuckle at those mountain valleys.

 

Most of the time I hate where I live because I am so damn close to the Potomac and relatively mild conditions.

 

This time tho I am exuberantly happy. A half inch or more of ice is no fun at all, especially on powerlines and on tree limbs.

 

I might rise above freezing well before midnight. I am so happy about it I want to shout it from the housetops :)

Hate to break it to you but Dale City will likely be at or below freezing tonight
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Folks, what a great day you had today! 1/25/00 esque?

 

I think for the far NW DC burbs up through NE MD...yes...epic for them...basically a 6-10" surprise...i don;t hink anyone was thinking more than 3"...for me, I got what I expected as did most of immediate DC metro..but fun event for early dec

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