U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 241951 
Storm Prediction Center ac 241950 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0250 PM CDT Tue Apr 24 2018 

Valid 242000z - 251200z 

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

..There is a marginal risk of severe thunderstorms across South 

A few severe thunderstorms are possible across northwest Texas into 
the mid evening hours.. isolated strong-severe storms also may 
occur today over parts of Southeast Florida. 


Earlier thoughts regarding severe remain. No appreciable changes are 
warranted to marginal risk across northwest Texas. 

High-based convection is deepening across portions of the Texas South 
Plains from Andrews County to Yoakum County, this activity is 
evolving in good agreement with earlier cams guidance and subsequent 
upscale growth downstream is expected over the next few hours. 
Locally damaging winds and hail are the primary threats into the 

Low-level convergence is beginning to focus across the southern Florida 
Atlantic coast. Convection is focusing across this region and will 
soon move off the coast. Marginal risk remains for these storms for the 
next few hours. 

.Darrow.. 04/24/2018 

Previous discussion... /issued 1050 am CDT Tue Apr 24 2018/ 

A moist and moderately unstable air mass is present today over south 
FL, where dewpoints in the 70s and strong heating will contribute to 
afternoon MLCAPE values over 1500 j/kg. Scattered thunderstorms 
have begun to form along a weak front sagging into the area, with 
development likely to spread across the Southeast Florida peninsula 
through the afternoon. Low-level flow is weak/veered, but deep 
layer shear is sufficiently strong for a few strong to severe cells. 
Gusty winds and perhaps hail are the main threats. 

Southerly winds have drawn 50s dewpoints back into parts of 
west-central TX, where afternoon MLCAPE values over 1000 j/kg are 
expected. 12z cam solutions are consistent in the development of a 
cluster of thunderstorms this afternoon in the lbb/maf vicinity, 
spreading eastward toward abi this evening. Forecast soundings 
suggest sufficient effective shear for a few rotating cells capable 
of hail, but a rather quick transition to linear Mode is expected 
due to limited moisture and strong downdrafts. Weak low-level wind 
fields and isolated storm coverage limit confidence in a more robust 
severe event, so will maintain the ongoing marginal risk area. 

..eastern NC... 
A large shield of precipitation persists across eastern NC today, 
with little destabilization expected through the afternoon. While 
an occasional embedded rotating storm is possible, the overall 
severe risk appears low. 

West of the precipitation shield, mid-level dry air is spreading 
into east-central NC. A narrow corridor of marginal cape is 
expected to develop in this region, but weak forcing, limited 
convergence, and moist-adiabatic lapse rates suggest that updrafts 
will we rather weak. Therefore have removed the marginal risk from 
these areas. 


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