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January 12-13th Cold Smoke Obs and Nowcast


Bob Chill
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Just now, DCTeacherman said:

Adding up the lower bounds of the precipitation 6 hr maps I get about 0.5 inches for DC, so it should be a good run. 

Looks like DC gets near .6-.7 and Bal gets .4-.5 about a .1 or .2 increase for both cities. 

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5 minutes ago, heavy_wx said:

Just for fun, here is a good example of mesoscale banding indicated by some diagnostics of the 12z NAM.

 

The 750 mb heights (black), frontogenesis, and saturation equivalent potential vorticity (SEPV) are plotted above. SEPV is a measure of the stability of air parcels to slantwise and/or vertical displacements in a saturated environment. Regions of negative SEPV have been associated with mesoscale precipitation bands in winter storms. You can see that there is a band of negative SEPV from east of the Delmarva to northern MD, to the north of the closed 750-mb height contour.

There is also enhanced 750-mb frontogenesis in this region, associated with a thermally direct circulation (i.e., warm air rising to the south, cold air sinking north). This circulation provides lift, and in the aforementioned environment of conditional stability, leads to enhanced vertical motion within the general synoptic ascent.

An important thing to note with these diagonistics is that these circulations and regions of conditional instability occur within layers of the atmosphere, and are often sloped. For example, here is the same plot but for 850 mb:

 

You can see here that the main region of conditional instability and enhanced frontogenesis is displaced to the south over central VA and SE MD. These two levels are different horizontal slices through the same circulation; in this case the circulation is sloped to the north with height. Where this circulation intersects the dendritic growth zone (DGZ) is often where the most intense banded precipitation occurs, due to the region having the most efficient ice crystal growth and aggregation.

For more information, this is one good resource: http://cstar.cestm.albany.edu/CAP_Projects/Project6/Mesoscale_Structure/seminar (M. Greenstein).ppt

I've been waiting for you to chime in Heavy. Good to hear from you on this one. Looks like your area will be getting the goods down there in Laurel

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4 minutes ago, BrianW said:

I am in DC for a wedding tonight and have a jetblue flight back to Hartford from Reagan airport at 5 pm tomorrow. Thoughts on that flight happening? We were planning on taking a cab or uber to the airport. 

Looking forward to the storm though. Its been pretty much snowless back home in CT. 

It depends on the details of your plane's inbound flight.   And based on your route, your scheduled plane has a couple stops at Reagan before your flight.  But since the actual inbound is from Orlando, you might be OK.

 

https://flightaware.com/live/flight/N203JB

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1 minute ago, smokeybandit said:

It depends on the details of your plane's inbound flight.   And based on your route, your scheduled plane has a couple stops at Reagan before your flight.  But since the actual inbound is from Orlando, you might be OK.

 

https://flightaware.com/live/flight/N203JB

Jet Blue 1098 is my flight tomorrow at 530 pm. 

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1 minute ago, MillvilleWx said:

I've been waiting for you to chime in Heavy. Good to hear from you on this one. Looks like your area will be getting the goods down there in Laurel

 Yeah, hopefully it will be a good storm for us down here (my first). It will certainly be interesting to see how the banding sets up.

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5 minutes ago, BrianW said:

Jet Blue 1098 is my flight tomorrow at 530 pm. 

You should be good by 5:30. Could easily be delays but my guess is runways will easily be plowed and open by late afternoom. Deicing and arrival delays could mess with the schedule but outright cancellations are unlikely...unless a deathband sets up...

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