SWODY1
SPC AC 101629
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT WED JUN 10 2009
VALID 101630Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
FROM THE SRN PLAINS EWD TO THE CENTRAL APPALACHIANS....
...TX/OK/KS/MO THROUGH TONIGHT...
A LARGE CLUSTER OF THUNDERSTORMS IS DEVELOPING NEWD FROM W TX TOWARD
WRN OK IN A REGION OF ASCENT IMMEDIATELY DOWNSTREAM FROM A LEAD
SHORTWAVE TROUGH EJECTING NEWD OVER W TX...ALONG A MOISTURE GRADIENT
THAT IS RETREATING SLOWLY NWD. THIS EJECTING WAVE IS PRECEDED BY A
LARGE PLUME OF MID LEVEL MOISTURE/CLOUDS WHICH WILL SLOW SURFACE
HEATING...THOUGH CLOUD BREAKS IN EXISTENCE FROM NE OK INTO SW MO AND
THINNING CLOUDS OVER PARTS OF NW TX WILL ALLOW LOCALLY STRONGER
DESTABILIZATION. MODIFIED REGIONAL 12Z SOUNDINGS SUPPORT AFTERNOON
MLCAPE VALUES IN THE 2000-3500 J/KG RANGE...WHILE ASCENT/MOISTENING
DOWNSTREAM FROM THE EJECTING MID LEVEL TROUGH WILL HELP REDUCE
CONVECTIVE INHIBITION AND AID IN THE MAINTENANCE OF THE ONGOING
CONVECTION SPREADING NEWD FROM W TX.
MID-UPPER SWLY FLOW WILL INCREASE FROM SW TO NE WITH THE APPROACH OF
THE MID LEVEL WAVE TODAY /PER THE OBSERVED 50-60 KT FLOW FROM 2-5 KM
AGL AT MAF/LUB AND TCC/. THIS INCREASING FLOW WILL CONTRIBUTE TO
SUFFICIENT VERTICAL SHEAR FOR ORGANIZED STORM CLUSTERS...AND
POTENTIALLY SUPERCELLS. CYCLOGENESIS DOWNSTREAM FROM THE MID LEVEL
WAVE IS RATHER WEAK AND LOW-LEVEL FLOW IS NOT PARTICULARLY
WELL-ORGANIZED...THUS DAMAGING WINDS AND LARGE HAIL WILL BE THE
PRIMARY SEVERE THREATS THIS AFTERNOON/EVENING. LOW-LEVEL SHEAR WILL
BE A LITTLE STRONGER TO THE NE OF THE SURFACE WAVE AND ALONG THE
BAROCLINIC ZONE FROM EXTREME NE OK/SE KS INTO SW MO THIS AFTERNOON.
THIS AREA COINCIDES WITH THE LARGEST CLOUD BREAKS/STRONGEST SURFACE
HEATING AS WELL AS BOUNDARY LAYER DEW POINTS NEAR 70 F...THUS THE
POTENTIAL FOR MORE DISCRETE SUPERCELLS WITH A TORNADO OR TWO WILL BE
SOMEWHAT GREATER COMPARED TO AREAS FARTHER SW IN OK/TX.
ONGOING CONVECTION...OR ADDITIONAL DEVELOPMENT THIS
AFTERNOON/EVENING...COULD BE MAINTAINED AS AN MCS OVERNIGHT IN
ADVANCE OF THE EJECTING MID LEVEL TROUGH AND ASSOCIATED SURFACE WAVE
ACROSS ERN KS/MO AND PERHAPS IL NEAR THE END OF THE PERIOD.
...OH/TN VALLEYS EWD TO VA/WRN NC THIS AFTERNOON...
A COUPLE OF EMBEDDED SHORTWAVE TROUGHS FROM IL/INDIANA SWD TO WRN TN
WILL CONTINUE TO BE ASSOCIATED WITH SEVERAL THUNDERSTORM CLUSTERS
FROM NRN AL TO ERN KY AND WV. SURFACE HEATING AND INSTABILITY ARE
SOMEWHAT GREATER IN ADVANCE OF THE AL CLUSTER...COMPARED TO LESSER
BOUNDARY LAYER MOISTURE AND MORE WIDESPREAD CLOUDS IN ADVANCE OF THE
CONVECTION ACROSS KY/WV. GIVEN ADDITIONAL DESTABILIZATION THROUGH
EARLY-MID AFTERNOON...THE NRN AL STORM CLUSTER COULD EVENTUALLY POSE
A THREAT FOR DAMAGING WINDS AND MARGINALLY SEVERE HAIL WHILE IT
PROGRESSES SEWD.
THE DAMAGING WIND/HAIL THREAT FARTHER N ACROSS KY/WV IS MORE
MARGINAL THAN YESTERDAY AS A RESULT OF WEAKER LAPSE
RATES/INSTABILITY. A LITTLE GREATER THREAT FOR SEVERE STORMS MAY
EXIST JUST E OF THE APPALACHIANS AS THE CONVECTIVE CLUSTERS AND
ASSOCIATED MID LEVEL WAVE REACH THIS AREA LATER THIS AFTERNOON.
SPECIFICALLY...STRONGER SURFACE HEATING AND RICHER BOUNDARY LAYER
MOISTURE ACROSS WRN VA WILL RESULT IN A LITTLE GREATER INSTABILITY
COMPARED TO AREAS FARTHER W...AND BEFORE HIGH CLOUDS OVERSPREAD THE
AREA THIS AFTERNOON.
...HIGH PLAINS AREA THIS AFTERNOON/EVENING...
WIDESPREAD CLOUDS AND A MID LEVEL MOISTURE PLUME WILL CONTINUE TO
OVERSPREAD THE TX/OK PANHANDLES...WRN KS...AND ERN CO IN ADVANCE OF
THE MID LEVEL TROUGH EJECTING NEWD OVER NM. SURFACE HEATING WILL BE
LIMITED BY THE CLOUDS...AND MID LEVEL LAPSE RATES ARE SUBSTANTIALLY
WEAKER WITHIN THE MOIST PLUME...THUS INSTABILITY WILL BE LIMITED
THIS AFTERNOON. VERTICAL SHEAR WILL BE SUFFICIENT FOR
SUPERCELLS...BUT WILL OUTLOOK ONLY LOW SEVERE PROBABILITIES GIVEN
THE AFOREMENTIONED INSTABILITY CONCERNS.
..THOMPSON/GARNER.. 06/10/2009
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