U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 161949 
Storm Prediction Center ac 161948 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0248 PM CDT Mon Sep 16 2019 

Valid 162000z - 171200z 

..no severe thunderstorm areas forecast... 

severe risk appears likely to remain minimal today and tonight. 

No changes to the outlook are required at this time, as prior 
reasoning and thunder areas continue to reflect the latest thinking. 
While a briefly strong/possibly severe storm cannot be ruled out 
over the Gulf Coast of Texas/Louisiana, parts of the west, including 
Arizona, this afternoon, and over the Minnesota vicinity tonight, 
risk appears too minimal in all areas to require addition of 
probability area. 

.Goss.. 09/16/2019 

Previous discussion... /issued 1110 am CDT Mon Sep 16 2019/ 

A deep midlevel trough, with associated cool midlevel temperatures 
and steep lapse rates, will continue to progress inland over the 
Pacific coast today and the Great Basin tonight. Isolated to widely 
scattered thunderstorms will be possible across portions of the 
Pacific northwest into the Great Basin as the trough moves eastward. 
Elsewhere, multiple shortwave troughs will eject northeastward from 
the southern rockies into the northern plains, resulting in the 
potential for widely scattered thunderstorms from the High Plains 
today into portions of the Dakotas/Minnesota late tonight. A weak 
mid/upper-level trough over the northwestern Gulf will produce 
widespread convection, with some of this activity spreading inland 
into coastal portions of la/Texas later today and tonight. 

While a few stronger storms cannot be ruled out across the interior 
northwest/Great Basin into the intermountain west, near the Texas/la 
Gulf Coast, and also across the eastern Dakotas into Minnesota late 
tonight, the potential for severe thunderstorms is expected to 
generally remain low through the period. 


Mesoscale Discussion

acus11 kwns 162122 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 162122 

Mesoscale discussion 1980 
National Weather Service Storm Prediction Center Norman OK 
0422 PM CDT Mon Sep 16 2019 

Areas affected...southern Arizona 

Concerning...severe potential...watch unlikely 

Valid 162122z - 162245z 

Probability of watch issuance...5 percent 

Summary...a cluster of multicell thunderstorms is expected to 
continue for a few more hours with a threat for isolated large hail 
and damaging winds. 

Discussion...several strong thunderstorm cores have developed in the 
last hour in southern Arizona with a few 1.5 to 2 inch mesh cores. 
However, any threat of large hail or damaging winds should be 
isolated and limited in time due to the relatively unorganized 
nature of the convection. The 20z Yuma sounding shows flow less than 
20 knots below 8km with effective shear less than 20 knots. Given 
the weak flow, expect any additional convection to remain 
unorganized with occasional multicell clusters. Dewpoints from the 
mid 50s to low 60s and temperatures in the 90s have yielded MLCAPE 
around 1500 to 2500 j/kg which will continue to support additional 
robust updraft development for the next 1 to 2 hours, where prior 
convection has not destabilized the boundary layer. No Severe 
Thunderstorm Watch is expected. 

.Bentley/Edwards.. 09/16/2019 

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


Latitude...Lon 31761239 32271248 32781225 33081178 33081064 32601014 
31590968 31290977 31321111 31761239