U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 240441 
Storm Prediction Center ac 240440 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1140 PM CDT Mon Apr 23 2018 

Valid 241200z - 251200z 

..there is a marginal risk of severe thunderstorms across northwest 

..there is a marginal risk of severe thunderstorms over eastern 
North Carolina... 

A few severe thunderstorms are possible across northwest Texas 
during the evening and overnight, with scattered thunderstorms over 
North Carolina and southeast Virginia. 

An upper low will move from the Tennessee/Ohio valleys eastward toward the 
mid Atlantic, with a surface low drifting northeast across the 
Carolinas. Easterly surface winds will maintain a plume of 60s f 
dewpoints across NC as a warm front lifts north toward the Virginia border 
by 00z Wednesday. A few strong storms are possible with the aid of 
heating south of the warm front. 

To the west, a shortwave trough will drop southward across the 
Central High plains, with a belt of 50-70 kt midlevel westerlies 
from Colorado/nm into KS/OK. This system will help drive a cold front 
southward into eastern nm and the Texas Panhandle during the day, and 
into southwest Texas by Wednesday morning. Instability will increase 
across West Texas during the evening into the overnight, supporting a 
few strong storms. 

..northwest Texas... 
Strong heating will occur ahead of the cold front, with steep low 
and mid level lapse rates developing. MUCAPE on the order of 1000 
j/kg will develop, with cin eroded by late afternoon. Increasing 
westerlies aloft atop weak low-level easterlies will result in a 
sufficiently long hodograph to support a few long-lived cells 
capable of hail or gusty winds. Splitting cells and/or small line 
segments are the most likely storm Mode. 

Widespread rain and embedded storms are likely across much of 
eastern NC into Virginia during the morning which will lift northeast. 
These storms will be elevated, and instability will likely be too 
weak for any hail threat. Later in the day, air mass recovery is 
expected with heating. Forecast soundings indicate relatively poor 
lapse rates aloft despite some cooling aloft, and the presence of 
dry air. This, along with weak lift in the wake of the early-day 
warm advection suggests storms may have trouble becoming severe. 
Will maintain the marginal risk due to favorable low-level srh along 
with upstream heating, but overall the severe threat appears very 
low. An isolated strong wind gust will be the main threat, perhaps 
in association with weak mesocyclones. 

.Jewell/Gleason.. 04/24/2018 


Mesoscale Discussion

acus11 kwns 240040 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 240039 

Mesoscale discussion 0287 
National Weather Service Storm Prediction Center Norman OK 
0739 PM CDT Mon Apr 23 2018 

Areas affected...north-central and east-central Georgia 

Concerning...severe potential...watch unlikely 

Valid 240039z - 240145z 

Probability of watch issuance...5 percent 

Summary...a couple of transient supercells are possible for the next 
1-2 hours. 

Discussion...radar data over the past couple of hours has shown a 
couple of storms intermittently showing weak rotation (i.E., Weak 
supercells). A sharp gradient in buoyancy is evident per the 00z 
Atlanta and Charleston, SC raobs with around 1500 j/kg MLCAPE to 100 
j/kg, respectively along the warm frontal zone. Conversely, much 
stronger low-level shear was evident at Charleston but considerably 
weaker at kclx VAD and the Atlanta radiosonde observation. The overlapping area in 
between Charleston and Atlanta is also where the storms have been 
most prone to exhibit weak cyclonic rotation (also with sidelobe 
contaminated velocities). The expectation for the next few hours is 
the possibility for an isolated gust may continue but diminishing 
boundary-layer instability will likely lead to a lowering 
strong/severe risk. 

.Smith/Thompson.. 04/24/2018 

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


Latitude...Lon 32088224 32998369 33198407 33638401 33578317 33188239 
32718169 32088224