U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 130056 
Storm Prediction Center ac 130054 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0654 PM CST Wed Dec 12 2018 

Valid 130100z - 131200z 

..no severe thunderstorm areas forecast... 

isolated to scattered thunderstorms are expected to develop across 
east/southeast Texas and the arklatex region tonight. 

..synopsis and discussion... 
A southern-stream shortwave trough over northern Mexico this evening 
will pivot eastward across east/southeast Texas overnight, while 
another upper trough continues to dig southeastward over the 
southern High Plains. Low-level warm and moist air advection is 
forecast to modestly strengthen through the end of the period along 
the Texas coast and vicinity. Isolated to scattered thunderstorms 
appear likely to develop mainly after 06z across east/southeast Texas 
as large-scale forcing for ascent increases in tandem with the 
approach of the southern-stream shortwave trough. 

00z surface observations indicate low-level airmass recovery is 
still in early stages across the western Gulf of Mexico, with 
dewpoints mainly in the upper 50s to lower 60s. Forecast soundings 
from the NAM/rap along and just inland of the middle/Upper Texas coast 
show weak elevated instability developing overnight, with MUCAPE 
less than 1000 j/kg. Even through low-level shear conditionally 
supports some severe potential across this region in the 08-12z time 
frame, tendency for storms to remain slightly elevated suggests that 
the overall severe threat remains too low to include any 
probabilities through 12z Thursday morning. 

.Gleason.. 12/13/2018 


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