SWODY2
SPC AC 081658
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1158 AM CDT TUE SEP 08 2009
VALID 091200Z - 101200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LARGE SCALE PATTERN WILL NOT PROVE PARTICULARLY FAVORABLE FOR
ORGANIZED SEVERE THUNDERSTORMS DURING THE DAY2 PERIOD AS MID LEVEL
FLOW IS EXPECTED TO REMAIN VERY WEAK OVER THE CONUS AS MORE
PROGRESSIVE WLYS RESIDE OVER CANADA. IN THE ABSENCE OF MEANINGFUL
DEEP LAYER SHEAR...DIURNAL HEATING WILL BE INSTRUMENTAL IN MUCH OF
THE CONVECTIVE DEVELOPMENT/INTENSIFICATION...THOUGH SUBTLE WEAK
VORTICITY MAXIMA AND ROGUE MCV/S WILL ENHANCE THUNDERSTORM CLUSTERS.
IT APPEARS AN AXIS OF MORE NUMEROUS SHOWERS/THUNDERSTORMS WILL
DEVELOP ALONG SWD-SAGGING FRONTAL ZONE ACROSS THE CNTRL/SRN PLAINS
INTO THE SRN ROCKIES...THOUGH CONVERGENCE ALONG THIS BOUNDARY IS
EXPECTED TO REMAIN RATHER WEAK. EARLY MORNING NAM SUGGESTS A WEAK
MID LEVEL CIRCULATION WILL MEANDER INTO THE SRN HIGH PLAINS WHICH
SHOULD AID CONVECTIVE DEVELOPMENT ACROSS THIS REGION WHERE MLCAPE
VALUES SHOULD RANGE FROM 500-1000 J/KG...JUST ENOUGH FOR A FEW
ROBUST UPDRAFTS CAPABLE OF GENERATING MAINLY SUB-SEVERE WIND GUSTS.
FARTHER EAST...AN ELONGATED WEAK UPPER LOW WILL RESIDE ACROSS THE
LOWER OH VALLEY INTO THE MIDDLE ATLANTIC. THIS FEATURE WILL
MAINTAIN A SFC LOW JUST OFF THE VA/NC COAST...WITH AN INVERTED
TROUGH EXPECTED TO STRETCH NWWD INTO ERN VA. FORECAST SOUNDINGS FOR
THIS REGION SUGGEST NELY ONSHORE FLOW AND WEAK LOW LEVEL LAPSE RATES
WILL SEVERE LIMIT BUOYANCY ALONG THE ATLANTIC COAST. IF ANY
THUNDERSTORMS DEVELOP IT APPEARS CONVECTION WILL BE ROOTED WELL
ABOVE THE BOUNDARY LAYER...LIKELY NEAR 700 MB.
..DARROW.. 09/08/2009
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