SWODY1
SPC AC 261610
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1110 AM CDT MON SEP 26 2011
VALID 261630Z - 271200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON FROM ERN TN/KY
TO ERN OH/WRN PA...
...UPPER OH VALLEY THIS AFTERNOON...
THE OCCLUDING LOW OVER SE WI WILL WOBBLE CYCLONICALLY TO NRN IL AND
WEAKEN BY TONIGHT. FARTHER E...A SURFACE COLD FRONT WILL CONTINUE
TO MOVE EWD ACROSS TN/KY/OH THIS AFTERNOON. SURFACE TEMPERATURES
ARE EXPECTED TO WARM TO 75-80 F IN CLOUD BREAKS E OF THE FRONT FROM
ERN TN/KY TO WRN WV AND ERN OH THIS AFTERNOON...WHICH COMBINED WITH
LOW-MID 60S BOUNDARY LAYER DEWPOINTS WILL SUPPORT MLCAPE OF
1000-1500 J/KG. MEANWHILE...DEEP-LAYER VERTICAL SHEAR WILL REMAIN
FAVORABLE FOR ORGANIZED BOWING SEGMENTS AND EMBEDDED SUPERCELLS
WITHIN THE ERN PERIPHERY OF THE CLOSED LOW AND STRONGER HEIGHT
GRADIENTS ALOFT.
THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ON THE E EDGE
OF THE THICKER CLOUDS AND BAND OF ASCENT ACCOMPANYING THE COLD
FRONT...AND THEN SPREAD NEWD ACROSS ERN KY/WRN WV/ERN OH/WRN PA
THROUGH LATE AFTERNOON. VERTICAL SHEAR/INSTABILITY WILL BE
SUFFICIENT FOR A DAMAGING WIND RISK THIS AFTERNOON...ALONG WITH THE
POSSIBILITY OF AN ISOLATED/BRIEF TORNADO.
...CENTRAL LA/MS/AL THIS AFTERNOON...
A BAND OF THICK CLOUDS PERSISTS ALONG THE SURFACE COLD FRONT FROM
NRN LA ACROSS NRN MS/AL. STRONGER SURFACE HEATING JUST S/SE OF THIS
CLOUD BAND WILL RESULT IN DESTABILIZATION AND WEAKENING OF
CONVECTIVE INHIBITION...AND SHOULD ALLOW NEW THUNDERSTORM
DEVELOPMENT BY EARLY-MID AFTERNOON. THE STRONGER FLOW ALOFT WILL
REMAIN N OF THIS AREA...BUT MULTICELL CLUSTERS COULD STILL PRODUCE A
FEW STRONG/DAMAGING GUSTS THIS AFTERNOON.
...NE TX/NRN LA OVERNIGHT...
A LOW-LEVEL WAA REGIME WILL BECOME ESTABLISHED OVERNIGHT IN
CONJUNCTION WITH THE DEVELOPMENT OF A 25-30 KT SWLY LLJ ACROSS E TX.
MUCAPE COULD EXCEED 2500 J/KG AS A RESIDUAL STEEP LAPSE RATE PLUME
COMBINES WITH WARM SECTOR BOUNDARY LAYER DEWPOINTS IN THE LOW-MID
70S. ASCENT WILL BE STRONGEST JUST N OF THE STALLED SURFACE FRONT
FROM NE TX INTO NRN LA...WHERE A FEW ELEVATED THUNDERSTORMS SHOULD
FORM OVERNIGHT...THOUGH STORM COVERAGE IS SOMEWHAT IN QUESTION GIVEN
THE WARMTH OF THE ELEVATED MIXED LAYER/CAP. ANY STORMS THAT FORM
WILL HAVE SOME POTENTIAL TO PRODUCE AT LEAST ISOLATED LARGE HAIL.
..THOMPSON/HURLBUT.. 09/26/2011
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