U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 250046 
Storm Prediction Center ac 250045 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0745 PM CDT Mon Apr 24 2017 

Valid 250100z - 251200z 

..no severe thunderstorm areas forecast... 

isolated thunderstorms remain possible across the eastern Carolinas 
this evening, with isolated weak thunderstorms expected to continue 
from The Rockies into the Central Plains. 


Center of upper low has progressed to near the Georgia/SC border this 
evening. Latest water vapor imagery depicts significant mid-level 
drying has wrapped into this feature which appears to be partly 
responsible for weak buoyancy that is supporting a small cluster of 
weak thunderstorms across southern SC. 00z sounding from chs 
supports this mid-level drying with mu cape on the order of 800 
j/kg. In the absence of significant forcing this activity should 
gradually weaken over the next few hours. 

00z soundings across the interior west depict steep mid-level lapse 
rates north of a strengthening mid-level jet that extends from California 
into the central rockies. Diurnal heating appears mostly 
responsible for scattered weak convection along the cyclonic side of 
the jet and isolated lightning with this activity should gradually 
wane later this evening with loss of heating. However, large-scale 
forcing for ascent will increase across the Central Plains late 
tonight as low level jet increases over OK/KS. Weak elevated convection 
should evolve across this region and the strongest updrafts should 
attain heights necessary for lightning discharge. 

.Darrow.. 04/25/2017 


Mesoscale Discussion

acus11 kwns 240232 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 240232 

Mesoscale discussion 0552 
National Weather Service Storm Prediction Center Norman OK 
0932 PM CDT sun Apr 23 2017 

Areas affected...southeast Georgia...central/eastern SC 

Concerning...severe potential...watch unlikely 

Valid 240232z - 240500z 

Probability of watch issuance...20 percent 

Summary...thunderstorms are expected to persist into late tonight, 
especially across portions of South Carolina. The strongest cells 
will be capable of locally damaging wind and perhaps a tornado or 
two. Watch issuance is considered unlikely at this time. 

Discussion...thunderstorms have recently increased in coverage and 
intensity across portions of eastern Georgia into west-central SC. This 
increase occurred in conjunction with a collision of the 
westward-moving sea breeze and an eastward-moving outflow boundary 
emanating from earlier convection over Georgia. The resulting composite 
boundary extends southward from a weak surface low over eastern GA, 
with another nearly-stationary boundary extending eastward from the 
low across central SC. 

A few cells have exhibited weak rotation across portions of 
west-central SC in Aiken and Barnwell counties, though these are 
likely slightly elevated and up to now have not appeared to pose an 
appreciable severe risk. Cells further south have shown less 
organization, but as they advance eastward into a somewhat more 
unstable airmass across the coastal plain of SC, some increase in 
intensity is possible with a risk of locally damaging wind in the 
short term. 

Later this evening, a modest increase in the low-level jet is 
anticipated in response to a well-defined upper low that will move 
slowly east-southeastward into Georgia. As this occurs, cells that are 
able to interact with the frontal boundary (which may move slowly 
northward as a warm front with time) may pose a threat of a brief 
tornado or two, though widespread convection and relatively weak 
deep-layer shear will likely keep the severe threat relatively 
limited. While a low-end severe threat will exist for much of the 
night, the magnitude of the threat at any particular location and 
time is currently expected to remain too limited for watch issuance. 

.Dean/guyer.. 04/24/2017 

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


Latitude...Lon 32718163 33238157 33728142 34058052 33997956 33827892 
33227913 32787973 32368044 31878113 31948167 32278171