U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 191613 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1013 am CST Fri Jan 19 2018 

Valid 191630z - 201200z 

..no severe thunderstorm areas forecast... 

isolated thunderstorms will be possible along the Texas and central 
California coasts. 

A weak midlevel trough will continue to drift eastward near the 
northwest Gulf Coast. Though the weakly unstable warm sector and 
the majority of the deep convection remains offshore, weak midlevel 
buoyancy does extend inland over the Texas coastal plain per the 12z 
sounding at Corpus Christi. Low-level warm advection should 
maintain some weak midlevel convection, and the potential for 
isolated lightning strikes, through early afternoon. 

Otherwise, an upstream shortwave trough is progressing 
east-southeastward toward California. Low-topped convection accompanies the 
midlevel thermal trough per satellite imagery, and a few lightning 
flashes have been detected off the central California coast as of 16z. Weak 
surface-based buoyancy will reach the immediate central California coast 
later today in conjunction with the steeper low-midlevel lapse 
rates, though thunderstorm coverage should remain isolated, at best. 

.Thompson/Gleason.. 01/19/2018 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 180309 

Mesoscale discussion 0031 
National Weather Service Storm Prediction Center Norman OK 
0909 PM CST Wed Jan 17 2018 

Areas affected...the Outer Banks area of North Carolina into the 
Tidewater area of southeast Virginia 

Concerning...heavy snow 

Valid 180309z - 180715z 

Summary...heavy snow rates in excess of 1 inch per hour, including 
occasional heavier convective bursts, may develop across the North 
Carolina Outer Banks area, possibly into portions of the Virginia 
Tidewater, during the 11 PM to 4 am time frame. 

Discussion...a significant mid-level trough is forecast to continue 
pivoting east of the southern Appalachians during the next few 
hours. As it does, models suggest that it may take on more of a 
neutral to negative tilt, accompanied by an increasingly better 
defined lower/mid tropospheric cyclonic circulation center across 
the Piedmont through coastal areas. This appears likely to 
contribute to a consolidating area of upward vertical motion, with 
considerable strengthening by the 05-08z time frame, centered across 
the Outer Banks area of North Carolina. 

Aided by dynamic cooling, cold advection and melting precipitation, 
thermodynamic profiles near immediate coastal areas are expected to 
cool entirely below freezing, supporting snow or a changeover to 
snow. Rapid refresh forecast soundings indicate that lift may 
become maximized within the dendritic growth layer for several 
hours, supporting snow rates in excess of 1 inch per hour, in the 
presence of precipitable water between .5 and .75 inches. At least 
some convective enhancement appears possible leading to occasional 
heavier bursts of snow, before diminishing/spreading offshore after 

It is possible similar snow rates could impact portions of the 
southeast Virginia Tidewater, but the most prolonged/heaviest snow 
appears most likely to the south, across the Outer Banks area 
near/north of Cape Hatteras. 

.Kerr.. 01/18/2018 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 36377656 36697547 34977525 35127595 35307683 36377656