U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 121616 
Storm Prediction Center ac 121615 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1015 am CST Wed Dec 12 2018 

Valid 121630z - 131200z 

..no severe thunderstorm areas forecast... 

isolated thunderstorms are expected to develop across portions of 
southwest Texas today, and across east/southeast Texas and the 
arklatex region tonight. 

A midlevel trough now over eastern or/ID/northern Nevada will dig 
southeastward to the southern High Plains by Thursday morning, as a 
separate southern stream trough ejects eastward from baja to the 
northwest Gulf of Mexico. Lee cyclogenesis will continue to draw a 
modifying Continental air mass northward from the western Gulf, and 
boundary-layer dewpoints will increase slowly into the 60s along the 
Texas coast through tonight. There could be sufficient midlevel 
moistening/destabilization for isolated/weak thunderstorms this 
afternoon/evening across southwest Texas in advance of the ejecting 
southern stream trough. Overnight, low-level moistening and 
strengthening ascent will support thunderstorm development in a 
loose band from the Texas coast northward to The Ark-la-tex. The 
magnitude of buoyancy should remain rather modest (mucape less than 
1000 j/kg) through this period and convection will likely be 
slightly elevated, both of which will tend to limit any threat for 
severe storms. 

.Thompson/leitman.. 12/12/2018 


Mesoscale Discussion

acus11 kwns 091734 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 091734 

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... 


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