Thursday, September 15, 2011

DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 150853
SWOD48
SPC AC 150853

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0353 AM CDT THU SEP 15 2011

VALID 181200Z - 231200Z

...DISCUSSION...
WITH 00Z ECMWF/GEFS GUIDANCE IN GENERAL LARGE SCALE AGREEMENT
THROUGH EARLY NEXT WEEK...PROGRESSIVE WESTERLIES ARE EXPECTED TO
PERSIST ESPECIALLY OVER THE NORTHERN TIER OF THE CONUS/CANADA. WHILE
SOME SEVERE TSTMS WILL BE POSSIBLE /AS BELOW/...NO 30 PERCENT
EQUIVALENT SEVERE RISK AREAS ARE CURRENTLY WARRANTED.

ON DAY 4/SUNDAY...WITH A RELATIVELY MOIST/POTENTIALLY UNSTABLE
AIRMASS AHEAD OF A WEAK/SLOW EAST-SOUTHEASTWARD MOVING
FRONT/TROUGH...SOME STRONG/PERHAPS SEVERE TSTMS MAY BE POSSIBLE ON
AN ISOLATED BASIS ACROSS PORTIONS OF THE SOUTHERN PLAINS/LOWER MO
VALLEY. BUT WITH THE PRIMARY NORTHERN TIER SHORTWAVE TROUGH LIKELY
TO BE PASSING OVER THE UPPER MIDWEST/GREAT LAKES REGION...LIMITED
LARGE SCALE SUPPORT/VERTICAL SHEAR WILL COINCIDE WITH THE BRUNT OF
THE MOIST SECTOR.

FOR DAYS 5-6 MONDAY/TUESDAY...A SECONDARY SHORTWAVE TROUGH SEEMS
LIKELY TO AT LEAST GRAZE A GRADUAL NORTHWARD EXPANSION OF MOISTURE
ACROSS THE PLAINS/MIDWEST EARLY NEXT WEEK. ACCORDINGLY...CURRENT
THINKING IS THAT ISOLATED SEVERE TSTMS MAY BE POSSIBLE ESPECIALLY
DAY 6/TUESDAY IN AREAS SUCH AS THE MIDDLE MO VALLEY/UPPER MIDWEST.

..GUYER.. 09/15/2011

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