SWODY2
SPC AC 050600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT MON OCT 05 2009
VALID 061200Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF MS/AR/LA WSWWD
ACROSS CENTRAL TX...
...SYNOPSIS...
WHILE AN UPPER LOW DEVELOPS NEAR/JUST OFF THE CA COAST AND A SECOND
DRIFTS NEWD OUT OF NEW ENGLAND AND ACROSS THE CANADIAN MARITIMES...A
SHORT-WAVE TROUGH PROGGED TO CROSS THE MIDWEST/OH VALLEY/GREAT LAKES
REGION WILL REMAIN THE PRIMARY FEATURE ALOFT WITH RESPECT TO THE
SEVERE/CONVECTIVE FORECAST THIS PERIOD.
AS THIS FEATURE MOVES QUICKLY EWD...AN ASSOCIATED SURFACE SYSTEM
WILL DO LIKEWISE. A COLD FRONT -- INITIALLY TRAILING FROM A LOW
INVOF IA SSWWD INTO CENTRAL OK AND THEN ON INTO SOUTHWEST TX -- WILL
MOVE QUICKLY EWD ACROSS THE MS/TN/OH VALLEYS THROUGH THE
DAY...LIKELY ARRIVING E OF THE APPALACHIANS BY THE END OF THE
PERIOD. SWD PROGRESS WILL BE LESS RAPID HOWEVER...WITH THE TRAILING
PORTION OF THE FRONT PROGGED TO EXTEND FROM N GA WSWWD ACROSS THE
GULF COAST STATES AND INTO S TX AT THE END OF THE PERIOD.
...OH VALLEY REGION SWWD INTO TX...
SHOWERS AND STORMS WILL BE ONGOING AHEAD OF THE SURFACE COLD FRONT
AT THE START OF THE PERIOD...FROM THE UPPER GREAT LAKES REGION SWWD
ACROSS THE MID AND UPPER MS VALLEY INTO OK/TX. VERY LIMITED
POTENTIAL FOR HEATING/DESTABILIZATION FROM ROUGHLY THE MID MS/TN
VALLEY REGION NWD WILL HINDER APPRECIABLE SEVERE POTENTIAL AS
CONVECTION SPREADS EWD THROUGH THE PERIOD...AND THUS WILL INCLUDE
ONLY 5% SEVERE PROBABILITY ACROSS THIS REGION DESPITE THE PASSAGE OF
A SIGNIFICANT FRONT AND VERY STRONG ACCOMPANYING FLOW ALOFT.
FARTHER SW -- FROM THE LOWER MS VALLEY REGION WSWWD ACROSS CENTRAL
TX...A GREATER POTENTIAL FOR HEATING SUGGESTS AFTERNOON MIXED-LAYER
CAPE VALUES AVERAGING 500 TO 1000 J/KG AHEAD OF THE FRONT ACROSS
THIS REGION. THOUGH MOST OF THE LARGE-SCALE UPPER SUPPORT FOR
ASCENT WILL REMAIN WELL N OF THIS AREA...STORMS SHOULD INCREASE
THROUGH THE AFTERNOON NEAR AND N OF THE FRONT AS IT SHIFTS SWD/SEWD
WITH TIME.
WHILE STRONGER FLOW ALOFT WILL REMAIN N OF THE FRONT...30 TO 40 KT
MID-LEVEL WSWLYS ATOP SLY BOUNDARY-LAYER WINDS WILL YIELD SHEAR
SUPPORTIVE OF ORGANIZED -- AND IN SOME CASES ROTATING -- STORMS.
HAIL WILL LIKELY BE THE PRIMARY SEVERE THREAT -- WITH SOME OF THE
CONVECTION EXPECTED TO BE ELEVATED N OF THE SURFACE FRONT. ANY
SURFACE-BASED STORMS -- PARTICULARLY OVER ERN PORTIONS OF THE SLIGHT
RISK AREA WHERE THE FLOW ALOFT WILL CROSS THE SURFACE FRONT AT A
GREATER ANGLE -- WILL ALSO POSE A THREAT FOR LOCALLY-DAMAGING WINDS.
SEVERE POTENTIAL SHOULD BEGIN WANING OVERNIGHT...WITH HAIL LIKELY
TO BECOME THE MAIN SEVERE THREAT WITH ONGOING/ELEVATED STORMS.
..GOSS.. 10/05/2009
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