DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 180855
SWOD48
SPC AC 180854

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0354 AM CDT SUN AUG 18 2013

VALID 211200Z - 261200Z

...DISCUSSION...
AN UPPER-LEVEL SHORTWAVE TROUGH IS FORECAST TO ENTER ONTARIO DURING
WEDNESDAY. AS THIS OCCURS...A SURFACE COLD FRONT WILL BECOME
POSITIONED FROM THE UPPER GREAT LAKES REGION WSWWD INTO THE
NRN/CNTRL HIGH PLAINS. A MOIST BOUNDARY LAYER AIRMASS LOCATED ALONG
THE FRONT WILL RESIDE BENEATH STEEP MIDLEVEL LAPSE RATES AND AID IN
STRONG BUOYANCY DURING THE AFTERNOON/EVENING. THIS WILL SUPPORT A
RISK FOR SEVERE THUNDERSTORM DEVELOPMENT FROM NRN NEB INTO SD AS
WELL AS SRN/CNTRL MN AND NRN IA. HOWEVER...SEVERE POTENTIAL DOES NOT
APPEAR TO WARRANT A 30 PERCENT DELINEATION ATTM.

BEYOND D4...MODELS CONTINUE TO SHOW DIFFERENCES IN THE LOCATION OF
AN UPPER-LEVEL ANTICYCLONE...WHICH IMPACTS THE PREDICTABILITY OF
WARM/MOIST SLY RETURN FLOW OVER THE N-CNTRL CONUS. DESPITE THE
SPREAD IN MODEL SOLUTIONS...A SEVERE STORM THREAT MAY EXIST FROM THE
NRN HIGH PLAINS EWD INTO THE UPPER MIDWEST DURING THE D5 THROUGH D8
PERIOD.

..GARNER.. 08/18/2013

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