U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 110527 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1127 PM CST Mon Dec 10 2018 


Valid 111200z - 121200z 


..no severe thunderstorm areas forecast... 


... 
severe thunderstorms are not expected across the contiguous U.S. 
Today through tonight. 


..western Washington/northwest or... 
A progressive, strong and cold Pacific mid-upper level trough will 
approach the Washington/or coast by 00z, and advance inland across the 
Pacific northwest region during the second half of the forecast 
period. Preceding this trough, a widespread area of precipitation 
is expected within a zone of ascent along the warm conveyor belt. 
Steepening lapse rates are expected across coastal and inland 
locations of Washington/or poleward of an expected 100+ kt 500-mb jet 
accompanying the Pacific trough, as sub -30 c temperatures spread 
across this region. Forecast soundings suggest buoyancy will become 
deep enough for some lightning to occur, given weak destabilization 
in the Post-frontal convection zone across coastal areas of Washington and 
northwest or this evening, and possibly inland to the Washington and 
northern or Cascades. 


... 
A large area of Continental polar high pressure will settle across 
the southeast U.S. And into the Gulf, maintaining stable conditions 
inland. 


.Peters/Cook.. 12/11/2018 


$$ 

Mesoscale Discussion


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Mesoscale discussion 1705 
National Weather Service Storm Prediction Center Norman OK 
1134 am CST sun Dec 09 2018 


Areas affected...portions of northern NC into southern WV and 
central/southern Virginia 


Concerning...heavy snow 


Valid 091734z - 092230z 


Summary...heavy snow will continue for a few more hours across parts 
of northwest NC and the higher terrain of southern WV and and 
western Virginia. Heavier snowfall also will continue to spread northeast 
into parts of central Virginia into early evening. A mix of snow and 
freezing rain and/or sleet also is possible across north-central NC 
into south-central Virginia the next few hours. 


Discussion...expansive area of moderate to heavy snowfall continues 
across parts of NC, WV and Virginia early this afternoon. The surface low 
is currently located just offshore the SC coast, and will continue 
to shift northeast near the NC coast through this evening. Midlevel 
moisture wrapping around the low level cyclone and forcing for 
ascent ahead of the approaching shortwave trough (currently over the 
Tennessee valley) will maintain wintry precip into the afternoon. A dry 
slot noted in WV imagery will continue to stream across NC and into 
eastern Virginia and some warming will occur over this area. As a result, 
snow may mix with freezing rain and/or sleet at times across 
north-central NC into south-central Virginia. 


Otherwise, cold air damming with a well-established cold conveyor is 
evident in observations across the Piedmont. Moderate to heavy snow 
will persist in this regime across the higher terrain and spread 
northeast into parts of central Virginia through the afternoon. Snowfall 
rates will generally be around 1 inch per hour, though heavier 
bursts approaching 2 inches per hour are possible. Precipitation 
will gradually wane from southwest (across nc) to northeast (wv and 
parts of va) late this afternoon into this evening. 


.Leitman.. 12/09/2018 


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


Attention...WFO...akq...lwx...rah...rnk...rlx...gsp...mrx... 


Latitude...Lon 35917922 35728036 35938125 36128151 36458188 36858190 
37438177 37808142 38068060 38447893 38507830 38447756 
38297706 38097673 37747670 37307681 37017694 36487754 
35917922