U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 230037 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0737 PM CDT Sat Apr 22 2017 

Valid 230100z - 231200z 

..there is a marginal risk of severe thunderstorms from the lower 
MS valley to northwest Georgia... 

Isolated strong storms are possible this evening along a corridor 
from southern Louisiana to northwest Georgia. Gusty winds and hail 
are the primary threats through mid evening. 


Large-scale mid-level height falls will spread across the central 
Gulf states tonight as strong 500mb speed Max translates across OK 
into the lower MS valley by sunrise Sunday. High-level diffluent 
flow should enhance upper venting for continued convection along the 
cold front as it advances across the remainder of la/MS into 
southern Alabama/northwest Georgia late tonight. However, 00z soundings 
across the central Gulf states exhibit only modest instability/shear 
such that robust convection capable of producing gusty winds and 
some hail may be noted...especially this evening south of I-20. 
Elsewhere along the front, draped across the southern Appalachians 
into NC, boundary-layer cooling and weak forcing will limit 
convection/severe threat along this portion of the wind shift. 

.Darrow.. 04/23/2017 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 222340 

Mesoscale discussion 0549 
National Weather Service Storm Prediction Center Norman OK 
0640 PM CDT Sat Apr 22 2017 

Areas affected...extreme southwest Tennessee /western NC...northwest 
Georgia...portions of central into northeast Alabama 

Concerning...Severe Thunderstorm Watch 158... 

Valid 222340z - 230045z 

The severe weather threat for Severe Thunderstorm Watch 158 

Summary...a general weakening trend is expected heading into the 
evening hours. A few strong/marginally severe storms may persist 
another 1-2 hours, producing strong wind gusts and perhaps small 
hail. However, threat will diminish with time and eastward extent 
and a downstream watch is not expected. 

Discussion...scattered strong to severe thunderstorms along a line 
from far western NC/southwest Tennessee through central Alabama into southern MS 
will continue to track east this evening. In general, recent 
weakening trend should continue with loss of daytime heating and a 
stabilizing boundary layer. Modest midlevel lapse rates and adequate 
deep layer shear should sustain storms into the evening, and in the 
short term /next 1-2 hours/ some strong gusts and small hail will be 
possible. Given the marginal nature of the threat downstream of ww 
158 and overall weakening trend, a downstream watch is not expected, 
and ww 158 likely will be able to be canceled before the 02z 
expiration time. 

.Leitman.. 04/22/2017 

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


Latitude...Lon 32238702 32038744 32008793 32128832 32668837 33378757 
34448630 35258490 35408431 35328391 35088375 34848384 
34298447 33978487 33048597 32238702