U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 250043 
Storm Prediction Center ac 250042 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0742 PM CDT Mon Sep 24 2018 

Valid 250100z - 251200z 

..no severe thunderstorm areas forecast... 

organized severe thunderstorms are not forecast through early 
Tuesday morning. 

Water-vapor imagery shows a mid-level trough over the Yellowstone 
National Park vicinity and this feature is forecast to move east to 
be near the Black Hills at sunrise. Isolated thunderstorms will 
accompany this perturbation mainly over the north-Central High 
plains as ascent overspreads the region. Farther east, a weak 
mid-level disturbance over the Ohio Valley will move northeast into 
the Lake Ontario/New York area. Numerous showers and widely scattered 
thunderstorms will gradually move north-northeast during the evening 
across the Tennessee Valley and into the central Appalachians during the 
overnight. The outflow-dominant character of the convection will 
preclude a severe risk. 

.Smith.. 09/25/2018 


Mesoscale Discussion

acus11 kwns 242055 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 242054 

Mesoscale discussion 1496 
National Weather Service Storm Prediction Center Norman OK 
0354 PM CDT Mon Sep 24 2018 

Areas affected...portions of central Tennessee and northern Alabama 

Concerning...severe potential...watch unlikely 

Valid 242054z - 242300z 

Probability of watch issuance...5 percent 

Summary...a few stronger/organized storms could develop over middle 
Tennessee and northern Alabama through this evening. Overall, the 
severe threat will remain isolated if it materializes. 

Discussion...a shortwave trough is moving over the southeast and 
Ohio River valley helping to spread ascent over the region. Within 
the warm sector including across Mississippi, Alabama, and most of 
Tennessee, a moist/unstable airmass is present and supportive of 
developing convection. MLCAPE of 750-1500 j/kg over middle 
Tennessee/northern Alabama with effective srh of 75-150 and bulk 
shear of 25-30 knots per mesoanalysis/rap soundings indicate the 
potential for a few weakly rotating storms. Bna radar has depicted a 
few storms with broad/weak rotation in the last hour across portions 
of middle Tennessee. A few stronger/organized storms are possible, 
but the overall severe threat remains marginal at best, thus a watch 
issuance is not expected. 

.Nauslar/Thompson.. 09/24/2018 

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


Latitude...Lon 35388699 35888682 36298650 36598615 36718558 36688530 
36548514 36288515 35918529 35508544 35128564 34858592 
34658612 34558634 34518659 34558689 34638716 34748719 
35208705 35388699