SWODY1
SPC AC 202000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT SAT SEP 20 2008
VALID 202000Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...UT/SOUTHERN ID AND WESTERN WY/SOUTHWEST MT...
WATER VAPOR IMAGERY REFLECTS AN UPPER TROUGH SHIFTING EAST-NORTHEAST
OVER ORE AND THE NORTHERN GREAT BASIN THIS AFTERNOON...WITH A STRONG
MID/UPPER JET STREAK RACING EASTWARD ACROSS THE GREAT BASIN. AMPLE
LARGE SCALE FORCING FOR ASCENT WILL SUPPORT ADDITIONAL TSTM
DEVELOPMENT THROUGH THE AFTERNOON/EVENING ACROSS THE INTERMOUNTAIN
REGION. RELATIVELY STRONG VERTICAL SHEAR AND MODEST
INSTABILITY/STEEP LAPSE RATES WILL FAVOR HAIL AND GUSTY WINDS WITH
THE STRONGEST TSTMS.
...UPPER MIDWEST...
SURFACE COLD FRONT WILL CONTINUE TO SPREAD SOUTH-SOUTHEASTWARD
ACROSS THE UPPER MIDWEST/GREAT LAKES REGION THROUGH TONIGHT. IN
SPITE OF LIMITED LARGE SCALE FORCING BENEATH RISING HEIGHTS
ALOFT...A WARM/DESTABILIZING BOUNDARY LAYER MAY ALLOW ISOLATED TO
PERHAPS SCATTERED TSTMS TO DEVELOP LATE THIS AFTERNOON/EARLY EVENING
ALONG THE COLD FRONT...RELATIVELY MORE LIKELY ACROSS THE SOUTHERN
PORTIONS OF MN/WI AND FAR NORTHERN IA. IN SPITE OF A FAVORABLE
THERMODYNAMIC ENVIRONMENT FOR A CONDITIONAL HAIL RISK...WEAK
VERTICAL SHEAR WILL CONSIDERABLY LIMIT ANY SEVERE POTENTIAL.
...LOWER/MIDDLE MISSISSIPPI VALLEY AND OH VALLEY...
WITH A SLOW MOVING/WEAK UPPER LOW CENTERED OVER EASTERN MO...A FEW
STRONG TSTMS WILL REMAIN POSSIBLE WITH FAIRLY COOL MID LEVEL
TEMPERATURES ATOP A WARM/MOIST BOUNDARY LAYER. WELL REMOVED FROM THE
STRONGER WESTERLIES...WEAK VERTICAL SHEAR ACROSS THE ENTIRE CORRIDOR
WILL KEEP ANY HAIL/WIND THREAT REMOTE.
..GUYER.. 09/20/2008
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