ACUS01 KWNS 151951
SWODY1
SPC AC 151949
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0249 PM CDT WED JUN 15 2011
VALID 152000Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE LOWER OH
AND TN VALLEY REGION...
...THERE IS A SLGT RISK OF SVR TSTMS FOR CENTRAL/SRN FL PENINSULA...
...TN VALLEY REGION...
CLUSTERS OF STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO CONTINUE
THROUGH THE AFTERNOON...ESPECIALLY ACROSS TN AND THE NRN PORTIONS OF
AL/MS/GA WITHIN WW 478. CONVECTION HAS BEEN SLOW TO DEVELOP SOUTH
OF THE WATCH AND MID AFTERNOON VISIBLE SATELLITE SUGGESTS THE AREA
IS SUBSIDENT. THE FLOW WILL EVENTUALLY BECOME MORE WNWLY ALOFT
OVERNIGHT...WITH STORMS MOVING MORE SEWD...AS SRN TAIL OF UPPER
TROUGH MOVES INTO REGION. IT APPEARS IT MAY TAKE LONGER FOR STORMS
TO REACH CENTRAL GA THAN EARLIER ANTICIPATED ...SO PORTIONS OF
SLIGHT RISK HAVE BEEN TRIMMED IN THIS REGION.
...IL/IND/FAR SERN MO...
STORMS HAVE RECENTLY DEVELOPED ALONG/AHEAD OF COLD FRONT STRETCHING
FROM CENTRAL IL SWWD INTO FAR SERN MO. A NARROW WEDGE OF MODERATE
INSTABILITY AND 35-40 KT DEEP LAYER SHEAR IS LOCATED AHEAD OF THE
FRONT...AND MAY BE SUFFICIENT FOR A FEW STORMS/SUPERCELLS WITH
SEVERE WINDS/HAIL. A SLIGHT RISK HAS BEEN INCLUDED FOR PARTS OF THIS
AREA...BUT STORMS SHOULD WEAKEN AS THEY REACH AS FAR EAST AS A
HUF-SDF-LOZ LINE...WHERE MORNING CONVECTION AND LEFTOVER CLOUDS HAVE
RESULTED IN A COOLER/MORE STABLE BOUNDARY LAYER.
...NRN TX/SRN OK...
ISOLATED STORMS MAY FORM LATER THIS AFTERNOON NEAR STATIONARY FRONT
LOCATED IN THE RED RIVER VALLEY REGION...WITH A THREAT OF DAMAGING
WINDS AND HAIL...REFERENCE MD 1231. HOWEVER...THE 10% THUNDER LINE
HAS BEEN REMOVED SOUTH OF THIS AREA DUE TO BUILDING HEIGHTS IN
CONJUNCTION WITH A WARMING/DRYING BOUNDARY LAYER.
..IMY.. 06/15/2011
.PREV DISCUSSION... /ISSUED 1122 AM CDT WED JUN 15 2011/
...TN VALLEY REGION THIS AFTERNOON...
THE PRIMARY MIDLEVEL TROUGH IS PROGRESSING EWD OVER TN AND THE LOWER
OH VALLEY. IN ADVANCE OF THIS SYSTEM...BANDS OF ELEVATED
THUNDERSTORMS ARE ONGOING IN THE ZONE OF WAA FROM MIDDLE TN INTO
CENTRAL KY...AND THESE STORMS MAY POSE A MARGINAL HAIL RISK.
FARTHER W/SW...A WARM FRONT IS MOVING NEWD INTO MIDDLE TN AND
CENTRAL/NRN AL. THE HIGHEST BOUNDARY LAYER TEMPERATURES AND
DEWPOINTS RESIDE ALONG AND W OF THIS BOUNDARY...AND SE OF A REMNANT
WSW-ENE ORIENTED OUTFLOW BOUNDARY FROM NRN AR INTO NW TN.
NEW STORMS ARE BEGINNING TO DEVELOP ALONG THE SURFACE BOUNDARIES
ACROSS WRN/MIDDLE TN IN AN ENVIRONMENT OF MLCAPE AOA 3000 J/G...AND
THIS CONVECTION COULD EVOLVE INTO ONE OR MORE CLUSTERS THAT WILL
MOVE EWD/SEWD ALONG THE WARM FRONT THIS AFTERNOON. 50 KT WLY
MIDLEVEL FLOW NOTED ON AREA VWPS/ WILL SUPPORT ORGANIZED CLUSTERS
CAPABLE OF PRODUCING DAMAGING WINDS...WHILE BUOYANCY/LAPSE RATES
WILL BE SUFFICIENT FOR LARGE HAIL.
...FL THIS AFTERNOON...
STRONG SURFACE HEATING IS UNDERWAY ACROSS FL...AND MODIFIED 12Z
SOUNDINGS SUPPORT AFTERNOON MLCAPE NEAR 3000 J/KG WITH LITTLE
CONVECTIVE INHIBITION. NWLY MIDLEVEL FLOW WILL ALLOW ORGANIZED
MULTICELL CLUSTERS TO PROPAGATE SWD/SWWD ALONG THE E COAST SEA
BREEZE...AND INTO THE WARMER INTERIOR WHERE THE STRONGEST
INSTABILITY WILL RESIDE. ALSO...WLY FLOW ALOFT WILL KEEP ANVIL
DEBRIS FROM SHADING THE STORM INFLOW REGIONS...WHICH WILL HELP
MAINTAIN STRONG INSTABILITY IN ADVANCE OF THE STORMS THROUGH THE
AFTERNOON. THE MORE INTENSE STORMS WILL HAVE THE POTENTIAL TO
PRODUCE DAMAGING WET MICROBURSTS...AS WELL AS MARGINALLY SEVERE
HAIL.
...IL/INDIANA THIS AFTERNOON/EVENING...
A LARGE CLUSTER OF THUNDERSTORMS HAS MOVED EWD INTO ERN KY/TN...WITH
A RESIDUAL OUTFLOW BOUNDARY NEAR THE TN/KY BORDER. N OF THIS
BOUNDARY...SURFACE DEWPOINTS LINGER IN THE MID-UPPER 60S...AND
CLEARING SKIES WILL ALLOW SURFACE HEATING THIS AFTERNOON.
HOWEVER...THE INITIAL MIDLEVEL TROUGH IS ALREADY MOVING OVER
IL...AND THE NEXT UPSTREAM WAVE WILL NOT IMPACT THIS AREA UNTIL
TONIGHT AND IN THE WAKE OF THE WAKE OF THE SURFACE COLD FRONT WHICH
IS NOW CROSSING THE MS RIVER. ISOLATED STORM DEVELOPMENT WILL BE
POSSIBLE...BUT THE COVERAGE/INTENSITY OF STORMS IS IN QUESTION.
THUS...WILL MAINTAIN LOW HAIL/WIND PROBABILITIES ACROSS THIS AREA.
...RED RIVER VALLEY OF TX/OK THIS AFTERNOON/EVENING...
A WEAKENING COLD FRONT WILL STALL NEAR OR JUST N OF THE RED RIVER
THIS AFTERNOON...AS THE ASSOCIATED MIDLEVEL TROUGH MOVES E OF THE MS
VALLEY. SURFACE HEATING WILL RESULT IN STRONG INSTABILITY ALONG AND
S OF THE FRONT...BUT THERE WILL BE LITTLE FOCUS FOR STORM
DEVELOPMENT OTHER THAN THE FRONT WHICH WILL BECOME MORE DIFFUSE WITH
TIME. GIVEN THE WEAKENING VERTICAL SHEAR WITH TIME AND UNCERTAINTY
REGARDING INITIATION...WILL MAINTAIN ONLY LOW HAIL/WIND
PROBABILITIES THIS AFTERNOON/EVENING.
...INTERIOR NEW ENGLAND AND ERN NY THIS AFTERNOON...
STRONG SURFACE HEATING AND RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE
MID 50S WILL ALLOW THE DEVELOPMENT OF 500-1000 J/KG MLCAPE THIS
AFTERNOON. A FEW THUNDERSTORMS WILL FORM OVER THE HIGHER TERRAIN
THIS AFTERNOON AND MOVE SWD AS MIDLEVEL FLOW WILL SLOWLY WEAKENS AND
BACKS FROM NELY TO NLY. MARGINALLY SEVERE HAIL AND STRONG OUTFLOW
GUSTS WILL BE POSSIBLE FOR A FEW HOURS THIS AFTERNOON WITH THE
STRONGER STORMS.
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