U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 240452 
Storm Prediction Center ac 240451 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1051 PM CST Thu Nov 23 2017 

Valid 241200z - 251200z 

..no severe thunderstorm areas forecast... 

isolated thunderstorms are possible across portions of the Florida 
Peninsula and Keys. No severe storms are anticipated. 

A pair of phased shortwave troughs will move east-southeastward 
during the period with the northernmost shortwave moving across the 
northern plains and the southernmost shortwave moving across the 
northern Great Basin and central rockies. An associated cold front 
will track quickly southeastward across the plains and Upper/Middle 
MS valley. However, in spite of these features and their related 
forcing for ascent, dry conditions will result in an environment 
hostile to deep convection. Farther south, shortwave trough 
currently moving through the base of the longwave trough covering 
the eastern Continental U.S. Will continue eastward through the Florida Peninsula 
early in the period. A few isolated thunderstorms are possible 
across the peninsula through the early afternoon, primarily along 
the west-central coast. Isolated thunderstorms will remain possible 
across southern Florida and the Keys during the afternoon and evening. 
Limited instability will temper updraft strength, keeping the severe 
threat very low. 

.Mosier/Cook.. 11/24/2017 


Mesoscale Discussion

acus11 kwns 231824 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 231823 

Mesoscale discussion 1776 
National Weather Service Storm Prediction Center Norman OK 
1223 PM CST Thu Nov 23 2017 

Areas affected...central Florida 

Concerning...severe potential...watch unlikely 

Valid 231823z - 232030z 

Probability of watch issuance...20 percent 

Summary...threat for a couple of damaging wind events and a brief 
tornado will persist through mid afternoon, primarily in a narrow 
corridor across north central Florida. Overall threat appears too 
marginal for a ww. 

Discussion...storms have undergone some intensification as they 
moved onshore just north of Tampa, possibly due to interaction of 
attendant NE-SW oriented convergence boundary with the seabreeze. 
Stationary front extends from just north of Tampa to north of 
Melbourne, and visible imagery shows thinning cirrus, allowing 
modest diabatic warming of the boundary layer in the warm sector 
where MLCAPE ranges from 500 to 800 j/kg over central Florida. Models 
indicate there should be some tendency for low-level winds to veer 
and weaken as a low-amplitude shortwave trough moves east of the 
peninsula later this afternoon. In the meantime, the more favorable 
low-level hodographs with 150-250 storm-relative helicity will 
persist in vicinity of the stationary front. Storms moving east and 
interacting with this boundary may develop occasional supercell 
structures and bowing segments, posing a risk for locally strong to 
damaging wind gusts and a brief tornado. The marginal thermodynamic 
environment and tendency for the low-level winds to veer and weaken 
later this afternoon suggest overall threat should remain limited. 

.Dial/Hart.. 11/23/2017 

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


Latitude...Lon 28538243 28818191 29178131 29198101 29008096 28628148 
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