U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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acus02 kwns 230541 
swody2 
Storm Prediction Center ac 230540 


Day 2 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1240 am CDT Fri Aug 23 2019 


Valid 241200z - 251200z 


..there is a marginal risk of severe thunderstorms across portions 
of the plains.... 


... 
Isolated severe storms are possible over parts of the central and 
northern Southern Plains on Saturday. A severe storm or two is also 
possible across the northern plains. 


... 
A shortwave trough is expected to move southeastward from the 
Central High plains across the Central Plains and into the Ozark 
Plateau on Saturday. Interaction between this shortwave and the 
moist air mass across the Central Plains is expected to result in 
thunderstorm development. 


Farther northwest, mean cyclonic flow aloft will progress eastward 
across western Canada and the northwestern/north-central Continental U.S.. 
consequently, enhanced mid-level westerly flow will extend from the 
Pacific northwest into the central rockies by the end of the period 
(12z sunday). A shortwave trough will move quickly eastward within 
this enhanced flow aloft along the US/Canada border. An associated 
surface low is expected to move eastward across Saskatchewan and 
Manitoba, with an attendant cold front moving across eastern Montana and 
into the western Dakotas. 


Expansive surface high centered over eastern Ontario/western Quebec 
will keep much of the northeast Continental U.S. Free of thunderstorms while 
warm and moist conditions will persist across the southeast. 


..central/Southern Plains... 
Thunderstorms will likely be ongoing from central NE southward into 
the eastern Texas Panhandle/western OK early Saturday morning. Strength 
and coverage of these storms will have an impact on air mass 
recovery and destabilization later during the afternoon. 
Additionally, outflow from these storms could provide a boundary for 
potential convective initiation. These mesoscale features introduce 
uncertainty into the forecast. Current expectation is for the air 
mass to destabilize by the late afternoon with isolated storms 
developing along the Lee trough extending from northeast nm into 
eastern Montana. Higher storm coverage is possible during the evening as 
a strengthening low-level jet promotes additional thunderstorm 
development across Kansas. 


The environment is characterized by favorable low-level moisture, 
steep mid-level lapse rates, and strengthening northwesterly flow 
aloft with enough vertical shear and buoyancy to support severe 
storms. Uncertainty regarding antecedent storms precludes higher 
probabilities with this outlook, but an upgrade may be needed in a 
subsequent outlook if mesoscale details become more clear. 


..northern plains... 
Elevated storms will likely be ongoing at the beginning of the 
period. Modest instability and shear support a marginal hail threat. 
Recent model guidance has trended towards less low-level moisture 
during the afternoon and evening across the northern plains. As a 
result, convective inhibition remains in place across much of the 
area, limiting surface-based storm initiation. Best location for 
surface-based initiation currently appears to be across 
north-Central/Northeast ND. Isolated storms are also possible late 
Saturday night/early Sunday morning along the approaching cold 
front. 


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


.Mosier.. 08/23/2019 


$$