SWODY1
SPC AC 211959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SUN SEP 21 2008
VALID 212000Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NORTHERN/CENTRAL
PLAINS...
...NORTHERN/CENTRAL HIGH PLAINS...
EARLY DAY TSTMS/BULK OF MID LEVEL CLOUD COVER WILL CONTINUE TO
PROGRESS EASTWARD ACROSS CENTRAL SD/NORTHERN NEB THIS AFTERNOON. IN
THE WAKE OF THIS ACTIVITY...GREATER INSOLATION/DESTABILIZATION
FARTHER WEST WILL LEAD TO AN UPSWING IN TSTM COVERAGE AND INTENSITY
LATE THIS AFTERNOON/EARLY EVENING INITIALLY IN VICINITY OF A HIGH
PLAINS LEE TROUGH...WITH TOWERING CU/TSTMS EVIDENT AT MID AFTERNOON
ACROSS THE WY/NORTHEAST CO FRONTRANGE. STEEPENING MID LEVEL LAPSE
RATES...ATOP UPPER 40S TO MIDDLE 50S F DEWPOINTS ALONG/EAST OF THE
LEE TROUGH...WILL CONTRIBUTE TO MLCAPE VALUES AS HIGH AS 750-1000
J/KG LATE THIS AFTERNOON. STRENGTHING FLOW ALOFT...AS REFLECTED BY
PROFILERS FROM MEDICINE BOW WY/PLATTEVILLE CO...AND VEERING WIND
PROFILES WILL BE FAVORABLE FOR WELL-ORGANIZED MULTICELLS AND SOME
SUPERCELLS /MOST LIKELY WEST-CENTRAL PORTIONS OF SD AND NEB/ CAPABLE
OF SEVERE HAIL AND STRONG WIND GUSTS. A SEVERE THREAT WILL GRADUALLY
DEVELOP EASTWARD TOWARD THE CENTRAL PORTIONS OF THE DAKOTAS/NEB
THROUGH THE EVENING. FOR ADDITIONAL SHORT TERM INFORMATION SEE
MESOSCALE DISCUSSION 2272.
...IL/IN...
MORNING UPPER AIR ANALYSIS AND MORE RECENT WATER VAPOR IMAGERY
REFLECTS A RESIDUAL UPPER LOW CENTERED NEAR THE ST LOUIS AREA THIS
AFTERNOON. A POCKET OF COOL MID LEVEL TEMPERATURES /-14 TO -16C AT
500 MB/ ATOP A WARM/MOIST BOUNDARY LAYER WILL PROMOTE A
LOCALIZED/PULSE-TYPE HAIL RISK WITH THE STRONGEST TSTMS THROUGH
AROUND SUNSET.
..GUYER.. 09/21/2008
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