DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 261614
SWODY1
SPC AC 261612

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1112 AM CDT MON OCT 26 2009

VALID 261630Z - 271200Z

...NO SVR TSTM AREAS FORECAST...

....SYNOPSIS...
BROAD TROUGH OVER THE CENTRAL CONUS FROM THE UPPER MS VALLEY SWWD
INTO THE SRN ROCKIES IS FORECAST TO SHIFT EWD THROUGH THE
PERIOD...IN RESPONSE TO AN UPPER TROUGH AMPLIFYING SEWD FROM THE
PACIFIC NW INTO THE WRN GREAT BASIN. THE SRN PORTION OF THE SRN
ROCKIES TROUGH WILL SHARPEN AND EVOLVE FROM A POSITIVE TO A NEUTRAL
TILT AS IT MOVES INTO CENTRAL TX TONIGHT...AS A MID LEVEL JET MAX
SHIFTS FROM THE BACKSIDE INTO THE BASE OF THE SYSTEM. STRONG SURFACE
RISES OVER TX WILL CONTINUE TO PUSH A COLD FRONT AND ASSOCIATED
CONVECTION SWD OFF THE TX COAST BY LATE AFTERNOON. HOWEVER...
APPROACHING UPPER TROUGH WILL SLOW EWD MOTION OF FRONT/INVERTED
TROUGH ACROSS THE LOWER MS VALLEY.

...TX AND LA COASTAL REGION...
A MAJORITY OF THE STRONGER CONVECTION ALONG THE UPPER TX COAST WAS
LOCATED NORTH OF FRONT AND THIS TREND SHOULD CONTINUE UNTIL THE
BOUNDARY MOVES OFFSHORE. THE DEEP SLY FLOW ABOVE THE COLD FRONT AND
ELEVATED CONVECTION SUGGESTS THE THREAT FOR SEVERE IS VERY LOW.
HOWEVER...A WEAK WAVE APPEARS TO HAVE FORMED ALONG THE FRONT WEST OF
ALI...MOVING EWD AHEAD OF THE UPPER TROUGH. WARMING SURFACE
TEMPERATURES AND STRENGTHENING SHEAR AHEAD OF SURFACE WAVE MAY
PROVIDE ENOUGH SHEAR/INSTABILITY FOR A BRIEF SEVERE WIND GUST/WEAK
TORNADO UNTIL AROUND MID AFTERNOON.

SFC WAVE SHOULD GRADUALLY DEEPEN BY LATE TONIGHT IN THE NWRN GULF AS
UPPER TROUGH BECOMES LESS POSITIVELY TILTED. STRENGTHENING MID/HIGH
LEVEL WIND FIELDS AND PRESENCE OF SURFACE LOW WOULD PROVIDE A
SLIGHTLY MORE FAVORABLE ENVIRONMENT FOR ROTATING STORMS.
HOWEVER...FORECAST SOUNDINGS INDICATE INSTABILITY WILL BE VERY WEAK
WITH UPDRAFTS ROOTED AROUND 850 MB. MAIN THREAT FOR STRONGER STORMS
IS EXPECTED IN THE NWRN GULF NEAR THE PRIMARY SURFACE LOW PRESSURE
SYSTEM.

..IMY/JEWELL.. 10/26/2009

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