SPC AC 220553
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT TUE SEP 22 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS ARE CONSISTENT SHOWING A CUT-OFF LOW REMAINING NEARLY
STATIONARY OVER THE CENTRAL PLAINS TODAY...SOUTH OF PRIMARY BAND OF
WESTERLIES LOCATED ACROSS CANADA. AT THE SURFACE...A COLD FRONT
ASSOCIATED WITH THE UPPER SYSTEM WILL CONTINUE TO SURGE SWD FROM
CENTRAL INTO DEEP S TX...WHILE THE NERN EXTENT OF THIS BOUNDARY
MOVES MORE SLOWLY E TOWARD THE LOWER AND MID MS VALLEY.
...S TO SE TX...
STRONGEST FORCING FOR ASCENT...STEEPER LAPSE RATES...AND BAND OF
STRONGER MID LEVEL FLOW ATTENDANT TO THE UPPER LOW ARE EXPECTED TO
REMAIN WELL W AND NW OF THE COLD FRONT THIS FORECAST PERIOD. AT 12Z
TODAY...EXTENSIVE CLOUDINESS ASSOCIATED WITH AN ONGOING MCS IS
EXPECTED TO LIMIT DESTABILIZATION FROM E TX/LA NNEWD INTO PARTS OF
THE MID MS VALLEY. SURFACE HEATING AND RICH MOISTURE /SURFACE
DEWPOINTS IN THE UPPER 60S-LOWER 70S/ ARE EXPECTED TO RESULT IN
MLCAPE RANGING FROM AOB 1000 J/KG OVER SE TX TO 1500-2000 J/KG OVER
S TX. DESPITE THE LACK OF STRONG FORCING ALOFT...CONVERGENCE ALONG
THE COLD FRONT AND/OR INTERACTIONS WITH THE SEA BREEZE BOUNDARY
SUGGEST NEW TSTM DEVELOPMENT WILL BE LIKELY BY AFTERNOON FROM THE
UPPER TX COASTAL PLAIN TO S TX. EFFECTIVE BULK SHEAR TENDING TO
REMAIN AOB 30 KT ACROSS THE WARM SECTOR SHOULD LIMIT A MORE
ORGANIZED SEVERE WEATHER THREAT. HOWEVER...MODERATE INSTABILITY AND
STEEPER LOW LEVEL LAPSE RATES WILL BE SUPPORTIVE OF SOME STRONGER
TSTM CLUSTERS OR LINE SEGMENTS CAPABLE OF ISOLATED DAMAGING WINDS
AND HAIL.
..PETERS/GRAMS.. 09/22/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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