SWODY2
SPC AC 240538
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1238 AM CDT SAT SEP 24 2011
VALID 251200Z - 261200Z
...NO SVR TSTM AREAS FORECAST...
...MID/LOWER MS VALLEY...
CENTER OF PSEUDO STATIONARY UPPER LOW WILL WOBBLE ABOUT THE IA/MO/IL
BORDER REGION AND THIS IS SUPPORTED IN BOTH THE LATEST GFS AND NAM
MODEL GUIDANCE. AT THE SFC...IT APPEARS A REINFORCED BOUNDARY WILL
SHARPEN ACROSS SERN MO/AR INTO NERN TX DURING THE DAY SUNDAY AS
STRONG HEATING DEVELOPS WITHIN THE BASE OF THE MID LEVEL CYCLONE.
AS A RESULT A NARROW ZONE OF STEEP LOW LEVEL LAPSE RATES WILL
ENHANCE AN AXIS OF INSTABILITY ALONG SRN FRINGE OF STRONGER CYCLONIC
FLOW ALOFT. THIS SHOULD ENHANCE THE LIKELIHOOD FOR FRONTAL
CONVECTION FAIRLY EARLY IN THE PERIOD...POSSIBLY AS EARLY AS 19-20Z
ACROSS IL/MO/KY...WITH SUBSEQUENT SWWD DEVELOPMENT ACROSS AR INTO
NRN LA BY 22-00Z. FORECAST SOUNDINGS SUGGEST FAVORABLE DEEP LAYER
SHEAR FOR STORM ORGANIZATION WITH SBCAPE VALUES POSSIBLY EXCEEDING
1500 J/KG. AT THIS TIME WILL ONLY INTRODUCE A 5% PROBABILITY FOR
DAMAGING WINDS AND HAIL DUE PRIMARILY TO THE EXPECTED NARROW AXIS OF
INSTABILITY AND THE LACK OF MOVEMENT OF THE UPPER LOW.
HOWEVER...THERE IS SOME CONCERN THAT A FRONTAL SQUALL LINE COULD
EMERGE SUCH THAT A NARROW WINDOW OF OPPORTUNITY MAY EXIST FOR A
GREATER RISK OF SEVERE. AN UPGRADE MAY BE REQUIRED IN LATER
OUTLOOKS IF THESE TRENDS CONTINUE TO LOOK FAVORABLE.
...ELSEWHERE...
ISOLATED THUNDERSTORMS WILL LIKELY DEVELOP BENEATH THE UPPER LOW
ACROSS IA/IL...EWD INTO THE OH VALLEY AS WELL AS PORTIONS OF THE
MIDDLE ATLANTIC INTO THE SERN U.S. WHERE DIURNAL HEATING WILL PROVE
INSTRUMENTAL IN DESTABILIZATION. OTHERWISE...A FEW HIGH BASED
STORMS MAY DEVELOP ACROSS SERN AZ/SWRN NM DUE TO STRONG HEATING
WITHIN A WEAK MID LEVEL THERMAL TROUGH.
..DARROW.. 09/24/2011
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