SWODY1
SPC AC 250515
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1215 AM CDT TUE AUG 25 2009
VALID 251200Z - 261200Z
...NO SVR TSTM AREAS FORECAST...
...MID-MO VALLEY AND CNTRL PLAINS...
WEST TO SOUTHWEST FLOW WILL BE IN PLACE ACROSS THE CNTRL STATES
TODAY AS A COLD FRONT MOVES SWD ACROSS THE CNTRL PLAINS AND UPPER MS
VALLEY. THIS BOUNDARY SHOULD BE A FOCUS FOR CONVECTIVE DEVELOPMENT
THIS AFTERNOON AND EVENING. MODEL FORECASTS ARE IN DISAGREEMENT
CONCERNING WHERE THE GREATEST COVERAGE OF THUNDERSTORMS WILL BE. THE
NAM AND ECMWF FOCUS CONVECTIVE DEVELOPMENT FROM ERN NEB ACROSS IA
INTO SRN WI WHILE THE GFS AND SREF FOCUS MORE ON SRN NEB AND CNTRL
KS. A LACK OF A SHORTWAVE TROUGH AND RELATIVELY WEAK LOW-LEVEL FLOW
SUGGEST ANY OF THE SOLUTIONS WILL BE POSSIBLE. FORECASTS DO AGREE
THAT MODERATE INSTABILITY WILL BE IN PLACE ALONG AND SOUTH OF THE
BOUNDARY FROM SW IA INTO ERN KS. IN ADDITION...ETA-KF FORECAST
SOUNDINGS SHOW VERY STEEP LOW-LEVEL LAPSE RATES ALONG THIS CORRIDOR
WITH 25-35 KT OF VERTICAL SHEAR. THIS MAY BE ENOUGH FOR MARGINALLY
SEVERE WIND GUSTS LATE THIS AFTERNOON AND EARLY THIS EVENING WHEN
INSTABILITY SHOULD BE MAXIMIZED.
FURTHER WEST...MODEL FORECASTS MOVE A WEAK SHORTWAVE-TROUGH EWD
ACROSS THE CNTRL ROCKIES. SCATTERED TO NUMEROUS THUNDERSTORMS SHOULD
DEVELOP AHEAD OF THE UPPER-LEVEL TROUGH THIS AFTERNOON WITH THE
CONVECTION MOVING SLOWLY EWD INTO THE CNTRL HIGH PLAINS BY THIS
EVENING. ALTHOUGH VERTICAL SHEAR PROFILES MAY BE STRONG ENOUGH FOR A
FEW SEVERE STORMS...INSTABILITY SHOULD REMAIN WEAK KEEPING ANY
THREAT MARGINAL.
..BROYLES/SMITH.. 08/25/2009
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