U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 130526 
Storm Prediction Center ac 130524 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1124 PM CST Mon Nov 12 2018 

Valid 131200z - 141200z 

..no severe thunderstorm areas forecast... 

severe thunderstorms are not expected today. 

..synopsis and discussion... 
A split-flow upper pattern will exist throughout the period across 
the central and eastern conus, downstream from the upper ridging in 
place along the West Coast. A southern-stream shortwave trough, 
currently moving through the southern High Plains, will continue 
slowly southeastward while gradually evolving into a closed low. By 
12z Wednesday, this closed low is expected to be centered over the 
arklatex. The northern stream will remain more progressive with the 
shortwave trough currently moving into the upper Great Lakes 
expected to continue eastward through the lower Great Lakes and 

At the surface, expansive high pressure will dominate much of the 
sensible weather across the Continental U.S.. one exception is across portions 
of the mid-Atlantic, where early period where thunderstorms are 
possible from the mouth of the Chesapeake Bay southward across 
coastal NC. A small area of surface-based instability may still 
exist across the barrier islands of NC, contributing to the 
potential for a strong storm or two. Even so, spatially limited risk 
area as well as the overall marginality of the threat precludes the 
need for any outlook areas. Isolated thunderstorms are also possible 
ahead of the front over southeast Georgia and across central/southern Florida 
as a result of diurnal destabilization. 

.Mosier/squitieri.. 11/13/2018 


Mesoscale Discussion

acus11 kwns 130516 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 130516 

Mesoscale discussion 1641 
National Weather Service Storm Prediction Center Norman OK 
1116 PM CST Mon Nov 12 2018 

Areas affected...portions of coastal NC/SC 

Concerning...severe potential...watch possible 

Valid 130516z - 130745z 

Probability of watch issuance...60 percent 

Summary...thunderstorms will move northeastward across parts of the 
coastal Carolinas overnight, with both an isolated tornado and 
strong to locally damaging wind threat. Watch issuance is possible. 

Discussion...a strong southerly low-level jet (around 40-50 kt) has 
developed over the eastern Carolinas per recent vwps from kltx and 
kmhx. Warm air advection attendant to the low level jet has encouraged recent 
thunderstorm development along a surface front very near the coast 
of SC as of 05z. A weak surface low is expected to develop 
northeastward along this boundary overnight, and continued warming 
and moistening of the low levels will likely occur across coastal 
NC/SC. Forecast soundings from latest rap/hrrr guidance indicate 
there will be some threat for surface-based thunderstorms where 
dewpoints can reach into the upper 60s to around 70. Strong speed 
shear mainly in the 0-1 km layer will contribute to large effective 
srh values across this region, potentially in excess of 300 m2/s2. 
Even though instability will remain weak owing to poor lapse rates 
through the column, MLCAPE up to 1000 j/kg will likely be sufficient 
for surface-based thunderstorms along/near the coast. Effective bulk 
shear values of 45-55 kt will support supercells, and the strong 
low-level shear suggests isolated tornadoes may occur with these 
storms. Strong to damaging straight-line winds will also be a 
possibility with any cluster that may evolve. Short-term guidance 
suggests an appreciable inland severe threat may develop near the 
coastal NC/SC border region by about 07z, and a watch may eventually 
be needed. 

.Gleason/Thompson.. 11/13/2018 

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


Latitude...Lon 33287880 33677920 33897923 34257874 34557823 35837665 
36047602 36067562 35667542 35207548 34997608 34547650 
33907789 33287880