SWODY1
SPC AC 191249
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0649 AM CST MON DEC 19 2011
VALID 191300Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CNTRL AND E TX...
...SYNOPSIS...
FAR W TX UPR LOW EXPECTED TO CONTINUE NE INTO THE TX PANHANDLE BY
THIS EVE AND INTO SW KS TUE MORNING AS UPSTREAM IMPULSE IN SPLIT
FLOW PATTERN ARCS S ACROSS CA TO OFF THE NRN BAJA CA CST. SFC LOW
ASSOCIATED WITH THE W TX SYSTEM SHOULD CONSOLIDATE OVER THE TX SOUTH
PLAINS LATER TODAY AND MOVE ENE INTO S CNTRL OK BY 12Z TUE. PACIFIC
COLD FRONT AND PRE-FRONTAL CONFLUENCE AXIS EXTENDING S FROM THE LOW
SHOULD ADVANCE E INTO CNTRL TX BY THIS EVE...AND TO NEAR THE LA
BORDER EARLY TUE...SERVING AS FOCI FOR STRONG TO POTENTIALLY SVR
STORMS.
...CNTRL AND E TX TODAY/TNGT...
50+ KT SLY LLJ WILL PERSIST AHEAD OF W TX UPR SYSTEM TODAY AND
TNGT...MAINTAINING NWD TRANSPORT OF MOISTURE ACROSS THE SRN PLNS AND
WRN PARTS OF THE LWR MS VLY. NEITHER SATELLITE NOR SFC DATA SHOW
PRESENCE OF ESPECIALLY MOISTURE-RICH AIR OVER THE NWRN GULF FOR THE
LLJ TO TAP. NEVERTHELESS...THE DATA DO SUGGEST THAT AHEAD OF
PACIFIC COLD FRONT...SFC DEWPOINTS WILL RISE INTO THE UPR 50S F AS
FAR N AS THE RED RIVER LATER TODAY. VALUES IN THE MID TO UPR 60S
APPEAR LIKELY OVER THE MIDDLE TX GULF CSTL PLN...WITH PW AOA 1.25
INCHES.
HEIGHT FALLS/FORCING FOR ASCENT ON LEADING EDGE OF W TX UPR
VORT...LOW-LVL UPLIFT ALONG ASSOCIATED PACIFIC FRONT...AND WEAK SFC
HEATING SHOULD FOSTER DEVELOPMENT OF AN ARC OF SFC TO NEAR SFC-BASED
TSTMS ALONG THE FRONT FROM ERN PARTS OF THE HILL COUNTRY NWD TO N
CNTRL TX BY MID TO LATE AFTN. THIS ACTIVITY SHOULD FAIRLY QUICKLY
EVOLVE INTO A BROKEN LINE AND CONTINUE E ACROSS THE I-35 CORRIDOR BY
EARLY EVE. OTHER...PERHAPS MORE DISCRETE STORMS MAY FORM A BIT
LATER IN THE DAY OR THIS EVE ALONG PRE-FRONTAL CONFLUENCE AXIS OVER
THE MIDDLE TX GULF CSTL PLN E/NE TO NEAR THE CLL AREA.
AS THE UPR LOW CROSSES THE SRN PLAINS...A BAND OF 60 TO 80 KT SSW TO
SWLY 500 MB FLOW WILL OVERSPREAD WARM SECTOR...YIELDING SHEAR/WIND
PROFILES FAVORABLE FOR SUSTAINED STORMS/SUPERCELLS. ALTHOUGH THE
STRONGEST FORCING FOR ASCENT AND SHEAR WILL RESIDE OVER N
TX...TEMPORAL BACKING OF MID LVL WINDS AND COMPARATIVELY WEAK LOW
LVL BUOYANCY /SBCAPE AOB 250 J PER KG/ SHOULD LIMIT THE SVR THREATS
TO LOCALLY DMGG WIND AND PERHAPS AN ISOLD TORNADO FROM LINE SEGMENTS
CONTAINING EMBEDDED LEWPS/SMALL BOWS. MORE SUBSTANTIAL SBCAPE /WITH
VALUES AOA 1000 J PER KG/ IS EXPECTED FARTHER S FROM CNTRL TX ESE TO
THE MIDDLE TX GULF CST. WHILE WIND PROFILES IN THIS REGION WILL BE
WEAKER RELATIVE TO POINTS N...ABSENCE OF TEMPORAL BACKING OF FLOW
AND PRESENCE OF GREATER INSTABILITY/WEAKER LINEAR FORCING FOR ASCENT
MAY SUPPORT A COUPLE SUPERCELLS CAPABLE OF TORNADOES...IN ADDITION
TO DMGG WIND. SOME OF THIS ACTIVITY MAY REACH THE CST
TNGT...AFFECTING AREA FROM PSX TO HOU/GLS.
THE SVR THREAT SHOULD DIMINISH LATER TNGT/EARLY TUE AS UPR LOW
CONTINUES NE INTO KS AND FORCING/SHEAR WEAKEN OVER SE TX.
...NW TX/SW OK THIS AFTN...
TSTMS SHOULD CONTINUE AND POSSIBLY INCREASE IN COVERAGE AND STRENGTH
TODAY OVER W CNTRL AND NW TX...IMMEDIATELY AHEAD OF LEAD VORT LOBE
ASSOCIATED WITH W TX UPR LOW AND ON NW EDGE OF LOW LVL MOISTURE
AXIS. SFC HEATING OVER REGION WILL BE NEGLIGIBLE. BUT COMBINATION
OF STRONG FORCING FOR ASCENT WITH STEEPENING MID LVL LAPSE RATES MAY
YIELD A FEW STORMS WITH HAIL. THE ACTIVITY COULD REACH SW OK BY
LATE AFTN/EARLY TNGT. WITH THE BOUNDARY LAYER REMAINING
COOL...BUOYANCY WILL REMAIN WEAK...LIMITING THE OVERALL THREAT.
..CORFIDI/HURLBUT.. 12/19/2011
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