U.S. Severe Weather Forecast (Konvektiivne väljavaade)

Day Three

acus01 kwns 091946 
Storm Prediction Center ac 091945 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0145 PM CST sun Dec 09 2018 

Valid 092000z - 101200z 

..no severe thunderstorm areas forecast... 

a few thunderstorms remain possible over the southern Florida 
Peninsula through early evening, but no severe weather is expected. 


The marginal risk category has been removed for the rest of the 
period. A band of pre-frontal, shallow convection with little to no 
lightning will continue through southern Florida into the early evening. 
However, deeper forcing accompanying a low-amplitude, deamplifying 
shortwave trough is moving through the middle Atlantic and will 
remain well north of the warm sector. Moreover, the attendant 
southwesterly low-level jet is gradually shifting northeastward away 
from the peninsula, resulting in weakening convergence and 
decreasing 0-2 km hodograph size. These factors along with the weak 
thermodynamic environment should limit any further threat for severe 

.Dial.. 12/09/2018 

Previous discussion... /issued 1024 am CST sun Dec 09 2018/ 

..central Florida through 18-21z... 
A pre-frontal band of thunderstorms is moving eastward across 
central Florida as of mid-late morning, with a few embedded rotating 
updrafts noted. Clouds are slowing surface heating, but 
temperatures have warmed into the low 70s immediately in advance of 
the ongoing convection, with boundary-layer dewpoints in the 68-70 f 
range. SBCAPE near 1000 j/kg and effective bulk shear in excess of 
50 kt will maintain a threat for at least isolated/organized severe 
storms for the next few hours. Low-level shear has peaked within 
the warm sector, and will begin to weaken by 18z as the primary 
midlevel trough and surface Cyclone Pass to the north of central Florida. 
Thus, there will be a window of opportunity for a tornado and/or 
isolated damaging gusts through early afternoon, with any severe 
threat expected to diminish by 21z. 


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