DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 261246
SWODY1
SPC AC 261244

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0744 AM CDT SAT OCT 26 2013

VALID 261300Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS N-CENTRAL TO W-CENTRAL
TX...

...SYNOPSIS...
IN MID-UPPER LEVELS...HIGH-AMPLITUDE SYNOPTIC PATTERN WILL PERSIST
THROUGH PERIOD...WITH BROAD CYCLONIC FLOW ASSOCIATED WITH TROUGHING
OVER ERN NORTH AMERICA AND WRN CONUS MEAN RIDGING. MAIN UPPER-AIR
FEATURE AFFECTING CONVECTIVE POTENTIAL THIS PERIOD WILL BE
POSITIVELY TILTED TROUGH...NOW EVIDENT IN MOISTURE CHANNEL IMAGERY
AND AVAILABLE RAOB DATA FROM WRN KS SWWD ACROSS NRN TX PANHANDLE TO
ERN NM. EMBEDDED VORTICITY MAX...WHICH HAS BEEN 500-MB CIRCULATION
CENTER...WAS MOVING EWD FROM NM OVER SRN PANHANDLE REGION OF TX.
TROUGH IS EXPECTED TO MOVE ESEWD ACROSS CENTRAL/SRN HIGH PLAINS
TODAY...REACHING WRN OK...NW TX AND TX PERMIAN BASIN REGION BY 00Z.
THEREAFTER...AS IT GETS ABSORBED INTO CONFLUENT SYNOPTIC-SCALE FLOW
REGIME ALOFT...TROUGH WILL GRADUALLY WEAKEN AND ACCELERATE
ESEWD...REACHING ARKLATEX REGION AND CENTRAL TX BY END OF PERIOD.

AT SFC...DRYLINE WAS DRAWN FROM NRN COAHUILA NWD ACROSS W-CENTRAL TX
INTO CENTRAL PORTIONS SOUTH-PLAINS AND PANHANDLE...NEAR I-27 AND
JUST W OF CAPROCK. MOIST ADVECTION TO ITS E AND VERTICAL MIXING TO
ITS W WILL BALANCE EACH OTHER ENOUGH TO MINIMIZE NET DRYLINE
MOVEMENT PRIOR TO FROPA DESCRIBED NEXT. COLD FRONT WAS DRAWN FROM
WEAK LOW IN DDC/GCK AREA SWWD ACROSS PORTIONS NERN/E-CENTRAL NM.
THIS FRONT SHOULD SHIFT SSEWD ACROSS SRN HIGH PLAINS...OVERTAKING
DRYLINE AND INTERSECTING DEVELOPING WARM FRONT OVER NW TX. BY
00Z...WEAK FRONTAL-WAVE LOW SHOULD EXIST OVER NW TX...WITH COLD
FRONT SWWD ACROSS TRANS-PECOS REGION. FRONT/INVERTED TROUGH WILL
EXTEND FROM LOW NEWD INTO PROGRESSIVELY COOLER AIR MASS...INCLUDING
ANTECEDENT RAIN-COOLED AIR...OVER CENTRAL OK. MEANWHILE WARM
FRONTAL ZONE WILL STALL OVER N-CENTRAL TX OR RED RIVER REGION E OF
LOW...ITS SPECIFIC POSITION INFLUENCED STRONGLY BY CLOUDS/PRECIP
OVER AND N OF THIS AREA DURING BULK OF DAYLIGHT HOURS. WEAK SFC LOW
SHOULD SHIFT EWD TO ESEWD ACROSS N-CENTRAL TX OVERNIGHT...WHILE COLD
FRONT PROCEEDS SEWD INTO EDWARDS PLATEAU REGION.

...W-CENTRAL...N-CENTRAL AND CENTRAL TX...
WIDELY SCATTERED TO SCATTERED TSTMS SHOULD DEVELOP ALONG/AHEAD OF
COLD FRONT AND DRYLINE THIS AFTN...AS WELL AS ON BOTH SIDES OF
DIFFUSE WARM FRONT. THIS WILL OCCUR IN ENVIRONMENT OF INCREASING
BUOYANCY AND BOUNDARY-LAYER MOISTURE THROUGH MID-LATE AFTN...ALONG
WITH STG VEERING OF WINDS WITH HEIGHT AND FAVORABLE
DEEP/CLOUD-BEARING LAYER SHEAR. COVERAGE SHOULD INCREASE WITH TIME
INTO LATE AFTN/EARLY EVENING AMIDST AT LEAST MRGLLY FAVORABLE DEEP
SHEAR...AND BECOME SUFFICIENT TO SUPPORT CATEGORICAL SVR RISK FOR
PARTS OF THIS REGION. SEVERAL REPORTS OF SVR HAIL AND DAMAGING WIND
ARE POSSIBLE. TORNADO POTENTIAL IS MORE CONDITIONAL...GIVEN LACK OF
SUBSTANTIAL NEAR-SFC FLOW AND UNCERTAINTIES REGARDING DURATION OF
ANY SUPERCELLULAR STORM MODES THAT DO DEVELOP.

LIMITING FACTORS WILL INCLUDE LACK OF MORE ROBUST LOW-MIDDLE LEVEL
LAPSE RATES...RESTRICTING OVERALL BUOYANCY...AS WELL AS WEAK SFC
WINDS THAT COULD HINDER CONVERGENCE. STILL...PATCHES OF SUSTAINED
INSOLATION WILL AID IN REMOVING MLCINH AND...WITH SFC DEW POINTS
COMMONLY MID-50S TO LOW-60S F...BOOSTING PREFRONTAL/PRECONVECTIVE
MLCAPE INTO 1000-1500 J/KG RANGE. UNCONDITIONAL SVR POTENTIAL
BECOMES MORE UNCERTAIN WITH NWD EXTENT TO SRN OK...THOUGH ISOLATED
SVR HAIL CANNOT BE RULED OUT. MEANWHILE...AFTN/EARLY EVENING TSTMS
OVER N TX MAY EVOLVE INTO AT LEAST LOOSELY ORGANIZED BAND OR MCS AND
MOVE SEWD OVER CENTRAL TX LATE EVENING...OFFERING STG-DAMAGING GUSTS
AND ISOLATED HAIL NEAR SVR LEVELS AT FIRST. HOWEVER...SVR THREAT
SHOULD BECOME MORE MRGL/CONDITIONAL AS FOREGOING NEAR-SFC PARCELS
COOL DIABATICALLY.

..EDWARDS/COHEN.. 10/26/2013

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.