SWODY1
SPC AC 211258
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CDT WED OCT 21 2009
VALID 211300Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
SATELLITE DATA SUGGEST THAT NM UPR LOW HAS REACHED ITS SRN-MOST
POINT. THE SYSTEM SHOULD TRACK NE INTO IN FAR SE CO THIS
EVE...BEFORE CONTINUING NE INTO WRN KS EARLY THU. AHEAD OF THE
LOW...A WEAKER DISTURBANCE NOW CENTERED OVER NE TX WILL ELONGATE
NEWD INTO AR...WHILE UPR LVL REMNANTS OF T.S. RICK SHEAR NE INTO S
CNTRL TX LATE TONIGHT/EARLY THU.
AT THE SFC...WRN PART OF FRONT NOW EXTENDING FROM THE SRN HI PLNS
INTO IA SHOULD SURGE S INTO W TX TODAY AS A WAVE EVOLVES ALONG THE
BOUNDARY IN NW OK. THE WAVE SHOULD REACH ERN KS BY THE END OF THE
PERIOD. FARTHER S...A WEAK NW/SE FRONT LIKELY WILL DEVELOP OVER E
CNTRL TX LATER TODAY AND TONIGHT...MARKING CONFLUENCE ZONE BETWEEN
RELATIVELY COOL/DRY AIR EMANATING FROM SRN APPALACHIANS SFC RDG AND
INCREASINGLY MOIST AIR MOVING N ACROSS THE FAR WRN GULF.
...CNTRL/S TX INTO WRN LA...
FAIRLY SUBSTANTIAL MOISTURE /WITH PW AOA 1.50 INCHES AND SFC DEW
POINTS IN THE UPR 60S/ WILL CONTINUE TO STREAM N INTO CNTRL/E TX
AND...EVENTUALLY...WRN LA THIS PERIOD AS DEEP SLY FLOW PREVAILS IN
SE QUADRANT OF NM UPR LOW. CONVECTION/EMBEDDED THUNDER NOW
DEVELOPING ACROSS REGION EXPECTED TO PERSIST AND POSSIBLY INCREASE
IN COVERAGE THROUGH EARLY THU IN RESPONSE TO CONTINUED MOISTENING
AND SUSTAINED UPR DIFFLUENCE DOWNSTREAM FROM T.S. RICK.
WHILE LOW LVL WIND PROFILES LIKELY WILL BE FAVORABLE FOR LOW LVL
UPDRAFT ROTATION...THICK CLOUDS WILL KEEP LOW LVL LAPSE RATES WEAK
INVOF DEVELOPING WARM FRONT. AT THE SAME TIME...MID LVL LAPSE RATES
WILL BE LIMITED BY ANTICYCLONIC/SUBTROPICAL NATURE OF UPR PATTERN.
AS A RESULT...OVERALL TSTM COVERAGE SHOULD REMAIN LIMITED. BUT
COMBINATION OF INCREASING RICH LOW LVL MOISTURE AND MODERATE WIND
PROFILES WITH CONSIDERABLE LOW LVL VEERING SUGGESTS POTENTIAL FOR A
BRIEF TORNADO OR TWO...DESPITE WEAK SBCAPE /AOB 1000 J PER KG/.
THIS THREAT MAY PERSIST THROUGH EARLY THU INTO THE SABINE RVR VLY AS
LLJ SHIFTS NEWD.
...WRN/NRN TX INTO OK...
WIDESPREAD ELEVATED CONVECTION/EMBEDDED THUNDER EXPECTED TO
MOVE/DEVELOP NNE FROM W TX INTO N TX AND MUCH OF OK TODAY/TONIGHT AS
SUBSTANTIAL HEIGHT FALLS AND UPR DIFFLUENCE OVERSPREAD REGION AHEAD
OF UPR LOW. SFC TO 850 MB MOISTURE WILL CONTINUE TO INCREASE IN SLY
FLOW S AND E OF COLD FRONT. BUT AIR MASS WILL REMAIN LARGELY
RETURNING MODIFIED POLAR IN NATURE. COUPLED WITH WIDESPREAD CLOUD
COVER AND SHOWERS ASSOCIATED WITH LEAD IMPULSE IN TX...PROSPECTS FOR
SIGNIFICANT DESTABILIZATION LOOK SLIM.
NEVERTHELESS...MID LVL LAPSE RATES WILL SOMEWHAT STEEPEN THIS
AFTN/EVE FROM W CNTRL TX NEWD INTO SW OK AS MID LVL DRY SLOT ROTATES
NE ACROSS REGION. CONVERGENCE ALONG FRONT MAY SUPPORT A FEW
STRONGER STORMS POSING AN ISOLD SVR WIND/HAIL THREAT... ESPECIALLY
IN ANY AREAS WHERE BREAKS IN THE OVERCAST BOOST MUCAPE TO NEAR 500
J/KG.
..CORFIDI/JEWELL.. 10/21/2009
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