U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 260546 

Day 2 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1246 am CDT Mon Aug 26 2019 

Valid 271200z - 281200z 

..there is a marginal risk of severe thunderstorms from northwest 
Texas/southwest Oklahoma southeastward into western Louisiana... 

Isolated severe thunderstorms are possible from northwest 
Texas/southwest Oklahoma southeastward into western Louisiana on 

Maturing mid-latitude cyclone, centered near the southern 
Manitoba/Ontario border early Tuesday morning, is expected continue 
eastward into far northwest Ontario. Expansive cyclonic flow 
throughout the base of this system (and attendant enhanced westerly 
flow aloft) will also progress eastward over the Upper/Middle MS 
valleys into the Ohio Valley. 

Surface low attendant to this upper system is expected to be 
centered over northwestern Ontario Tuesday morning. A cold front 
will extend southeastward from this low into the upper Great Lakes 
then southwestward through the middle MS valley into southwest Texas. 
Northern/eastern portion of this front will remain progressive, 
continuing eastward through the Ohio Valley and lower Great Lakes. 
Southern/western portion of this front will be less progressive with 
outflow from an mesoscale convective system likely becoming the effective boundary across 
southern OK/northern Texas. 

..far northwest Texas/southeast OK into western la... 
Showers and thunderstorm will likely be ongoing at the beginning of 
the period as a decaying mesoscale convective system moves into the region. Isolated 
damaging wind gusts are possible with the strongest cells along the 
outflow boundary. 

Warm and moist conditions are anticipated south of the composite 
outflow boundary Tuesday afternoon. Mid-level temperatures will be 
relatively warm, but the warm and moist low-levels will likely 
result in an erosion of any convective inhibition. Convergence along 
the boundary will then lead to thunderstorm development. However, 
given the mesoscale nature of this boundary, its location is hard to 
ascertain with much confidence at this point. Most of the 
convection-allowing guidance suggests a more southerly boundary 
location during the afternoon and the 5% threat area was adjusted 

The lack of stronger vertical shear suggests minimal storm 
organization and a predominantly multicellular Mode. Even so, strong 
water-loaded downbursts are possible with the strongest updrafts. 

..upper Midwest... 
A shortwave trough embedded within the base of the larger parent 
mid-latitude cyclone is expected to move into the region during the 
afternoon. Cool mid-level temperatures and large-scale forcing for 
ascent associated with this trough will led to thunderstorm 
development. Given the weak instability, storms are generally 
expected to remain sub-severe with some small hail possible within 
the strongest updrafts. 

..maximum risk by hazard... 
Tornado: 2% - marginal 
wind: 5% - marginal 
hail: 5% - marginal 

.Mosier.. 08/26/2019