SWODY1
SPC AC 241241
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0741 AM CDT FRI SEP 24 2010
VALID 241300Z - 251200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
AN INITIAL SHORTWAVE TROUGH OVER THE UPPER GREAT LAKES WILL PROGRESS
ENEWD /ALONG AND N OF THE SAINT LAWRENCE VALLEY/ THROUGH EARLY
SATURDAY...WHILE AN UPSTREAM TROUGH NOW OVER THE NRN ROCKIES BEGINS
TO DIG SEWD OVER THE NRN/CENTRAL PLAINS LATE IN THE PERIOD. A COLD
FRONT ACCOMPANYING THE LEAD SHORTWAVE TROUGH WILL CONTINUE TO
PROVIDE A FOCUS FOR THUNDERSTORM DEVELOPMENT TODAY...PRIMARILY
ACROSS PARTS OF THE SRN PLAINS AND MS VALLEY WHERE LOW-LEVEL
MOISTURE/INSTABILITY WILL BE GREATEST. BUOYANCY WILL BE MUCH MORE
LIMITED FARTHER NE ALONG THE FRONT INTO THE MID-UPPER OH VALLEY AS A
RESULT OF A NARROWING MOIST SECTOR WITH TIME...AND POOR MIDLEVEL
LAPSE RATES. DAMAGING WINDS WOULD BE A MINOR CONCERN ACROSS THE OH
VALLEY GIVEN THE FORECASTS OF 30-50 KT WSWLY LOW-MIDLEVEL FLOW AND
STEEP LOW-LEVEL LAPSE RATES WITH DAYTIME HEATING.
HOWEVER...MARGINAL THERMODYNAMIC PROFILES WITH SMALL CAPE AND WARM
EQUILIBRIUM LEVEL TEMPERATURES WILL BE SOMEWHAT UNFAVORABLE FOR
LIGHTNING PRODUCTION WITHIN THE BAND OF SHALLOW CONVECTION ALONG THE
FRONT.
OVERNIGHT...LOW-MIDLEVEL ASCENT WILL INCREASE OVER THE CENTRAL
PLAINS/MID MO VALLEY IN ADVANCE OF THE AMPLIFYING MIDLEVEL
TROUGH...AND ON THE NOSE OF A DEVELOPING SWLY LLJ. A NARROW
CORRIDOR OF MOISTURE RETURN ABOVE THE SURFACE WILL OCCUR IN
CONJUNCTION WITH THE LLJ...BENEATH A PLUME OF RELATIVELY STEEP
MIDLEVEL LAPSE RATES. THE NET RESULT WILL BE AN ENVIRONMENT
SUPPORTIVE OF ELEVATED THUNDERSTORMS LATE TONIGHT...SOME OF WHICH
COULD PRODUCE MARGINALLY SEVERE HAIL GIVEN 500-1000 J/KG OF MUCAPE
AND COOL TEMPERATURES ALOFT.
..THOMPSON/GARNER.. 09/24/2010
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