SWODY1
SPC AC 111253
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CDT TUE OCT 11 2011
VALID 111300Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NW TX...THE TX
PANHANDLE...AND WRN OK...
...SYNOPSIS...
FAST PACIFIC JET WILL CONTINUE TO ADVANCE ESE FROM THE PACIFIC
NW/NRN GRT BASIN THIS PERIOD AS UPR RIDGES AMPLIFY OVER CALIFORNIA
AND THE WRN ATLANTIC. THIS WILL LEAD TO THE GRADUAL DEVELOPMENT OF
BROAD...NEGATIVE TILT TROUGH WITH NUMEROUS EMBEDDED SMALLER SCALE
DISTURBANCES OVER THE PLNS/MS VLY....AND CONTINUED WEAKENING/NEWD
EJECTION OF COMPLEX TROUGH OVER THE SERN STATES.
AT THE SFC...LEE TROUGH WILL BECOME BETTER DEFINED OVER THE HI PLNS
TODAY...AHEAD OF DEVELOPING COLD FRONT ASSOCIATED WITH PACIFIC JET.
IN THE EAST...BOUNDARY NOW PRESENT JUST OFF THE GA/SC/NC CST SHOULD
REMAIN NEARLY STNRY AS WEAKENING HYBRID UPR LOW NOW OVER GA/SC
BECOMES MORE EXTRATROPICAL AND LIFTS NEWD. THE NRN PART OF THE
BOUNDARY MAY EDGE INTO FAR ERN NC LATER TODAY/TNGT AS A SFC WAVE
MOVES NEWD ALONG IT.
...CNTRL/SRN PLNS THIS AFTN/EVE...
STRENGTHENING WNWLY MID/UPR LVL FLOW ASSOCIATED WITH PACIFIC JET
WILL ALLOW AN EML TO SPREAD ESE ACROSS WRN PORTIONS OF THE CNTRL AND
SRN PLNS LATER TODAY. LOW LVL MOISTURE RETURN ACROSS THE REGION
AHEAD OF LEE TROUGH WILL...HOWEVER...REMAIN LIMITED GIVEN RECENT
MODIFIED POLAR AIR INCURSION OVER THE SRN PLNS/LWR MS VLY.
NEVERTHELESS...COMBINATION OF STEEPENING MID LVL LAPSE RATES WITH
DAYTIME HEATING LIKELY WILL YIELD SUFFICIENT DESTABILIZATION /SBCAPE
FROM 500 TO 1000 J PER KG/ TO SUPPORT SCTD TSTMS ALONG AND AHEAD OF
THE TROUGH BY LATE AFTN. DEVELOPMENT WILL BE FURTHER ENCOURAGED BY
TIMELY ARRIVAL OF ELONGATED UPR IMPULSE NOW OVER CNTRL CO.
CONFIGURATION OF UPR TROUGH AND ASSOCIATED SPEED MAX SHOULD KEEP
DEEP SHEAR RELATIVELY WEAK IN KS AND NEB...WHERE 500 MB WINDS WILL
REMAIN AROUND 20 KTS. GREATER SPEED AND DIRECTIONAL SHEAR
WILL...HOWEVER...EXIST FARTHER S OVER THE SRN PLNS...ESPECIALLY IN
NW TX WHERE 40 KT WLY 500 MB FLOW WILL OVERLIE A 20-25 KT SSWLY LLJ.
GIVEN THIS SETUP...IT APPEARS THAT SOME MULTICELL STORMS COULD POSE
A MARGINAL HAIL/WIND THREAT IN KS/NEB. FARTHER S...A FEW SUPERCELLS
COULD ADD TO THE MIX IN NW TX AND THE TX PANHANDLE...WHERE SOMEWHAT
GREATER MOISTURE /PW TO 1 INCH WITH SFC DEWPOINTS IN THE UPR 50S F/
ALSO WILL BE PRESENT. SUCH STORMS WOULD BE CAPABLE OF ISOLD LARGE
HAIL AND LOCALLY DMGG WIND. WHILE THE SVR THREAT SHOULD DIMINISH
AFTER SUNSET...SCTD STORMS...SOME LIKELY ELEVATED...COULD PERSIST
INTO EARLY WED OVER THE CNTRL AND SRN PLNS.
...CSTL CAROLINAS/SE VA TODAY/TNGT...
40 KT ELY LLJ MARKING SRN EDGE OF RETREATING MID ATLANTIC SFC HIGH
WILL LIFT NWD ACROSS THE CAROLINAS TODAY AND INTO TIDEWATER VA
OVERNIGHT. AT THE SAME TIME...AFOREMENTIONED FRONTAL ZONE
ALONG/JUST OFF THE CST MAY EDGE SLIGHTLY N AND NWWD...ESPECIALLY
INTO FAR ERN NC. ON THE SRN EDGE OF THE LLJ...SUFFICIENT LOW LVL
BUOYANCY MAY DEVELOP IN THE VERY MOIST AIR /PW NEAR 2 INCHES/ TO
SUPPORT A FEW SHALLOW...WEAKLY-ROTATING SHOWERS/STORMS WITH A LOW
PROBABILISTIC THREAT FOR A BRIEF/WEAK TORNADO.
..CORFIDI/LEITMAN.. 10/11/2011
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