SWODY1
SPC AC 180100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0700 PM CST FRI FEB 17 2012
VALID 180100Z - 181200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS DEEP S TX TO MIDDLE TX
COAST...
...SYNOPSIS...
PRIOR SPLIT-FLOW PATTERN OVER WRN CONUS AND NRN MEX IS BECOMING MORE
PROGRESSIVE IN RESPONSE TO NRN-STREAM WAVE AMPLIFICATIONS. THIS IS
RESULTING IN OPENING/EJECTION OF PREVIOUSLY CLOSED LOW OVER
BORDERLANDS REGION OF TX/NM/CHIHUAHUA. ASSOCIATED STG SHORTWAVE
TROUGH IS EXPECTED TO BECOME LESS POSITIVELY TILTED THROUGH
REMAINDER PERIOD...MOVING TO POSITION NEAR AMA...INK...SWD OVER BIG
BEND NATIONAL PARK AND WRN COAHUILA.
AT SFC...APCH OF MID-UPPER TROUGH IS SUPPORTING LEE-SIDE
CYCLOGENESIS E OF NERN MEX MOUNTAINS...AND W OF MFE. RELATED SFC
LOW WILL MOVE NEWD ALONG WARM FRONT DRAWN AT 00Z ACROSS STAR/KENEDY
COUNTIES THEN EWD OVER GULF. LOW SHOULD MOVE TO COASTAL BEND/MIDDLE
COAST AREA NEAR VCT BY 12Z...WHILE WARM FRONT MOVES NWD TOWARD PSX
AND SW GLS. NWD MOVEMENT OF WARM FRONT TOWARD UPPER TX COAST WILL
BE IMPINGED BY ONGOING CONVECTION/OUTFLOW NOW OFFSHORE MID-UPPER TX
COAST.
...S TX...
SFC TEMPS 80S/90S F WERE MEASURED OVER RELATIVELY CLOUD-FREE SWATH
OF INTERIOR MEX PLATEAU EARLIER TODAY...EVIDENCE OF STG ELEVATED
MIXED-LAYER AIR MASS POTENTIALLY ADVECTED DOWNSTREAM ACROSS OUTLOOK
AREA TONIGHT. LAST VIS IMAGERY SHOWED STRATUS STILL DAMMED AGAINST
ERN SLOPES OF SERRANIAS DEL BURRO...EXTENDING EWD ON BOTH SIDES OF
FRONTAL ZONE ACROSS S TX AND ADJACENT PORTIONS NERN MEX. TSTMS HAVE
DEVELOPED AND INCREASED IN COVERAGE GREATLY OVER WRN COAHUILA DURING
PAST COUPLE HOURS...WHERE PLUME OF STRONGER MID-UPPER ASCENT AHEAD
OF SHORTWAVE TROUGH IMPINGED UPON WELL-HEATED/MIXED BOUNDARY LAYER
AND AT LEAST MRGLLY FAVORABLE MOISTURE. AS SWATH OF LIFT SHIFTS
EWD/ENEWD TONIGHT INTO RICHER LOW-LEVEL MOISTURE...CONVECTION SHOULD
EXPAND/REDEVELOP ACROSS RIO GRANDE AND OVER S TX ON EITHER SIDE OF
FRONT. GREATEST COVERAGE IS LIKELY IN ZONE OF ELEVATED WAA/MOISTURE
TRANSPORT N OF FRONT AND NW-N OF SFC LOW TRACK...WHERE FCST
SOUNDINGS SHOW 45-60 KT EFFECTIVE SHEAR MAGNITUDES EVEN FOR ELEVATED
BUOYANCY...IN SUPPORT OF HAIL THREAT.
S OF FRONT...SFC DEW POINTS UPPER 60S TO LOW 70S F WILL BE
MAINTAINED...ENABLING SFC-BASED EFFECTIVE INFLOW PARCELS IF
SUFFICIENT LIFT IS PROVIDED TO FORCE THEM THROUGH BASAL EML
INVERSION. FAVORABLE MLCAPE IN 2000-2500 J/KG RANGE WAS ESTIMATED
FROM 00Z BRO SOUNDING...EVEN AFTER CORRECTING FOR APPARENT WET-BULB
COOLING ARTIFACT AROUND 815 MB...ALONG WITH 50 KT EFFECTIVE SHEAR
MAGNITUDE. ATTM IT REMAINS UNCERTAIN HOW FAR S INTO WARM SECTOR ANY
CONVECTIVE BAND OR CLUSTER WILL BUILD...GIVEN STRENGTHENING EML
PLUME WITH SWD EXTENT...BUT MOISTURE AND DEEP-LAYER SHEAR WILL
REMAIN FAVORABLE. AS SUCH...WILL MAINTAIN CATEGORICAL-THRESHOLD SVR
PROBABILITIES NEAR AND S OF CYCLONE TRACK...AND OVER PORTIONS RIO
GRANDE VALLEY NW-W OF LOW TRACK WHERE SRN PORTION OF GREATEST TSTM
CONCENTRATION SHOULD JUXTAPOSE WITH MOST VIGOROUS WAA CONVEYOR.
..EDWARDS.. 02/18/2012
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