U.S. Severe Weather Forecast (Konvektīvā prognoze)

Day Three

acus01 kwns 211939 
Storm Prediction Center ac 211938 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0138 PM CST Tue Nov 21 2017 

Valid 212000z - 221200z 

..no severe thunderstorm areas forecast... 

no severe thunderstorms are forecast across the nation today. 

No changes are made to the outlook for this issuance. 

.Broyles.. 11/21/2017 

Previous discussion... /issued 1013 am CST Tue Nov 21 2017/ 

A large upper trough is present today over the central and eastern 
United States. Scattered showers and a few thunderstorms are 
expected to affect parts of Texas/la, as well as along the Carolina/Georgia 
coast and the Florida Peninsula. Strong storms are possible just off the 
immediate coast of both regions, with hail and gusty winds possible. 
However, current guidance suggests the risk of severe storms moving 
inland is low. 


Mesoscale Discussion

acus11 kwns 182324 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 182324 

Mesoscale discussion 1773 
National Weather Service Storm Prediction Center Norman OK 
0524 PM CST Sat Nov 18 2017 

Areas affected...portions of Tennessee and northern Alabama 

Concerning...Severe Thunderstorm Watch 517... 

Valid 182324z - 190130z 

The severe weather threat for Severe Thunderstorm Watch 517 

Summary...a squall line will continue east within and near watch 517 
this evening, with an attendant threat of a few damaging gusts and 
perhaps a tornado. The line should gradually weaken with eastward 
extent this evening, such that downstream watch issuance is not 
currently anticipated. 

Discussion...a nearly continuous line of thunderstorms is advancing 
across Tennessee and northern Alabama early this evening. Over the 
last hour, there was a localized uptick in tornado potential 
south/east of the Nashville area, with three distinct tornadic 
debris signatures in Rutherford, Wilson, and Trousdale counties. 
While cells will continue to outpace remaining low-level buoyancy, 
impressive low-level shear may still yield a quick tornado across 
middle Tennessee over the next hour. Otherwise, an isolated damaging 
wind threat will likely persist through the 01z expiration time of 
watch 517. 

Farther south, convection has at times consolidated into a few 
stronger segments over northern Alabama. Local observations have yet 
to indicate severe wind gusts, but considering the strength of 
low-level flow and presence of weak mixed-layer cape, isolated 
damage will remain possible for the next couple hours, before 
surface-based buoyancy is shunted farther south. 

.Picca.. 11/18/2017 

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


Latitude...Lon 34048819 36588602 36588440 36278421 34978545 34268621 
33988719 33918800 34048819