U.S. Severe Weather Forecast (Прогноз Конвекции)

после завтра

acus01 kwns 221937 
Storm Prediction Center ac 221935 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0135 PM CST Wed Feb 22 2017 

Valid 222000z - 231200z 

..no severe thunderstorm areas forecast... 

severe thunderstorms are not expected through tonight. 

No changes are made to the outlook for this issuance. 

.Broyles.. 02/22/2017 

Previous discussion... /issued 1030 am CST Wed Feb 22 2017/ 

An upper low over the eastern Gulf of Mexico will continue to slowly 
move southeastward toward South Florida through tonight. Numerous 
showers along with a few thunderstorms are ongoing across the 
peninsula and Keys vicinity, and related cloud cover should continue 
to hinder appreciable destabilization much of the afternoon, 
although modest destabilization may occur from west to east in the 
wake of ongoing precipitation with related low-topped thunderstorm 
redevelopment. Even so, the overall severe potential appears low 
given weak shear and poor mid-level lapse rates. 

An eastward-moving low-amplitude shortwave trough over the upper 
Midwest and upper Great Lakes, in conjunction with steep lapse rates 
and a minimally unstable air mass, will yield a few thunderstorms 
across the region into tonight. Additionally, a few thunderstorms 
may also occur along parts of the West Coast. 


Mesoscale Discussion

acus11 kwns 202038 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 202037 

Mesoscale discussion 0198 
National Weather Service Storm Prediction Center Norman OK 
0237 PM CST Mon Feb 20 2017 

Areas affected...parts of Louisiana and into far southwest 

Concerning...severe potential...watch unlikely 

Valid 202037z - 202230z 

Probability of watch issuance...20 percent 

Summary...a slow increase in storm intensity is ongoing, along with 
low-probability risk for an isolated damaging wind gust or two, or a 
brief tornado. At this time, it appears that risk will remain 
sufficiently limited to preclude the need for ww issuance. 

Discussion...latest surface analysis shows persistent southeasterly 
flow off the north-central Gulf of Mexico, contributing to both 
onshore advection of upper 60s to low 70s dewpoints, as well as some 
enhancement to the low-level shear profile. As a semi-organized 
band of storms continues crossing western Louisiana, a weakly 
heating/destabilizing airmass (characterized by around 750 j/kg 
mixed-layer cape) is contributing to some increase in updraft 
strength -- both within the line, and with isolated showers 
developing ahead of the main band of storms. 

While potential for additional destabilization is limited, low-level 
and deep-layer shear are both sufficient to support a few stronger 
cells, and at least weak/mid-level rotation. Indeed, a few cells 
immediately ahead of the main convective band have exhibited weak 
rotation per area WSR-88D data, and this will likely continue over 
the next several hours. Overall risk, however, appears likely at 
this time to remain marginal, and thus likely not requiring watch 

.Goss/guyer.. 02/20/2017 

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


Latitude...Lon 29749036 29169024 29079132 29409283 30819321 32059330 
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