DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 280556
SWODY2
SPC AC 280555

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT TUE AUG 28 2007

VALID 291200Z - 301200Z

..NO SVR TSTM AREAS FORECAST...

..OH VALLEY/LOWER MI...
AN UPPER-LEVEL TROUGH OVER THE UPPER-MIDWEST TONIGHT WILL MOVE EWD
INTO THE GREAT LAKES REGION WEDNESDAY. AT THE SFC...A COLD FRONT
WILL MOVE SEWD ACROSS SRN LOWER MI EXTENDING SWWD ACROSS THE LOWER
OH VALLEY DURING THE AFTERNOON. MODEL FORECASTS ARE RELATIVELY
CONSISTENT DEVELOPING MODERATE INSTABILITY AHEAD OF THE BOUNDARY
FROM AROUND DETROIT MI EXTENDING WSWWD ACROSS NRN IND AND NRN IL.
SCATTERED THUNDERSTORMS APPEAR LIKELY TO DEVELOP ALONG THE BOUNDARY
AND MOVE ESEWD ACROSS THE REGION INTO INCREASING INSTABILITY.
FORECAST SOUNDINGS WEDNESDAY AFTERNOON IN THE AREAS OF STRONGEST
INSTABILITY SHOW 0-6 KM SHEAR VALUES GENERALLY BELOW 20 KT. THIS
SHOULD LIMIT STORM ORGANIZATION SOMEWHAT WITH MULTICELLS OR PULSE
STORMS THE DOMINANT CONVECTIVE MODE. HOWEVER...SOME FORECAST
SOUNDING SHOW INVERTED-V PROFILES WITH STEEP LOW-LEVEL LAPSE RATES
AND LARGE SFC TEMP-DEWPOINT SPREADS. IF CONVECTION CAN FORM IN THIS
ENVIRONMENT...THEN A MARGINAL WIND DAMAGE THREAT MAY EXIST NEAR PEAK
HEATING.

..SE WY/ECNTRL CO/NE NM...
WLY FLOW ALOFT ACROSS THE CNTRL HIGH PLAINS TONIGHT WILL BECOME MORE
NORTHWESTERLY AS AN UPPER-LEVEL RIDGE AMPLIFIES ACROSS THE WRN
STATES. AT THE SFC...A QUASI-STATIONARY FRONT IS FORECAST TO BE
LOCATED FROM SE WY EXTENDING SEWD ACROSS ECNTRL CO. AS SFC TEMPS
WARM...SCATTERED TO NUMEROUS THUNDERSTORMS SHOULD INITIATE IN THE
HIGHER TERRAIN OF SE WY...CNTRL CO TO NE NM AND ALONG THE BOUNDARY
ACROSS ERN CO. REGIONAL FORECAST SOUNDINGS WEDNESDAY AFTERNOON SHOW
0-6 KM SHEAR VALUES IN THE 20 TO 30 KT RANGE WITH THE BETTER
DIRECTIONAL SHEAR LOCATED FROM DENVER TO CHEYENNE. THE AMOUNT OF
VERTICAL SHEAR ALONG WITH STEEP LAPSE RATES ESPECIALLY AT LOW-LEVELS
MAY BE ENOUGH FOR A MARGINAL WIND DAMAGE THREAT. A FEW HAIL REPORTS
WILL ALSO BE POSSIBLE WITH THE STRONGER CELLS ESPECIALLY IF A POCKET
OF MODERATE INSTABILITY DEVELOPS.

.BROYLES.. 08/28/2007

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