SPC AC 061308
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0808 AM CDT TUE OCT 06 2009
VALID 061300Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM S CNTRL TX ENE INTO THE
LWR MS/LWR TN VLYS...
...SYNOPSIS...
SPLIT FLOW PATTERN WILL CONTINUE OVER THE WRN HALF OF THE U.S.
THROUGH WED AS POSITIVE TILT UPR LOW SLOWLY REDEVELOPS SEWD ACROSS
CA...AND NRN STREAM TROUGH NOW OVER THE CNTRL/NRN PLNS CONTINUES E
TO THE LWR GRT LKS.
SFC LOW NOW OVER IA SHOULD CONTINUE E/ENE INTO SRN ONTARIO BY 12Z
WED...WITH SOME DEEPENING LIKELY. ASSOCIATED COLD FRONT WILL
ACCELERATE SE ACROSS THE MID MS VLY...OH...AND TN VLYS...AND
CONTINUE STEADILY SSE ACROSS THE SRN PLNS.
...SRN PLNS INTO LWR MS/TN VLYS...
BAND OF SLIGHTLY ELEVATED STORMS LIKELY WILL PERSIST THROUGH LATE
MORNING FROM NW TX ENE INTO SE OK AND WRN AR AS MOIST/CONFLUENT SW
TO WSWLY LLJ FURTHER VEERS IN RESPONSE TO CONTINUED EWD MOVEMENT OF
NRN STREAM TROUGH. QUALITY OF ASSOCIATED MOISTURE INFLOW /PW AOA
1.50 INCHES/ AND STRENGTH OF UNIDIRECTIONAL WSWLY CLOUD LAYER SHEAR
/50+ KTS/ SUGGEST POTENTIAL FOR POSSIBLE SUSTAINED STORMS AND
PERHAPS AN ADDITIONAL SUPERCELL OR TWO. HOWEVER...SVR THREAT SHOULD
DIMINISH AS LLJ WEAKENS LATER THIS MORNING AND COLD FRONT NOW
ENTERING N CNTRL TX UNDERCUTS EXISTING BAND OF STORMS.
IN THE WAKE OF MORNING ACTIVITY...ADDITIONAL STORMS EXPECTED THIS
AFTN AND EVE ALONG AND AHEAD OF SRN PLNS/LWR MS VLY COLD FRONT AS
HEATING AND PERSISTENT WSWLY LOW LVL SCOUR REMAINING PORTION OF
SHALLOW COOL AIR DOME NOW PRESENT NEWD FROM THE ARKLATEX.
TEMPERATURES WILL REMAIN RELATIVELY WARM AT 500 MB...AROUND MINUS 5
OR 6 C....FROM TX INTO AR AND WRN TN/NRN MS. IN ADDITION... FORCING
FOR ASCENT WILL BE LIMITED AS WEAK SHORTWAVE RIDGING SPREADS FROM NM
INTO TX IN WAKE OF NRN STREAM TROUGH. BUT A BELT OF 50+ KT DEEP
WSWLY MID LVL FLOW WILL PERSIST ON SRN FRINGE OF TROUGH. WITH SFC
HEATING AND CONTINUING PRESENCE OF RICH MOISTURE LIKELY TO BOOST
SBCAPE TO AROUND 2500 J/KG IN S CNTRL TX ENE INTO THE ARKLATEX...ANY
STORM FORMING ALONG/AHEAD OF COLD FRONT MAY BECOME SUFFICIENTLY
SUSTAINED/ORGANIZED TO POSE A THREAT OF DMGG WIND FROM ASSOCIATED
SMALL SCALE BOWS. VEERED LOW LVL FLOW WILL LIMIT TORNADO POTENTIAL.
A NON-ZERO TORNADO THREAT WILL...HOWEVER ...EXIST FROM NRN LA AND
CNTRL/SRN AR INTO ADJACENT PARTS OF TN AND MS WITH ANY SUSTAINED
STORMS/POSSIBLE SUPERCELLS THAT INTERACT WITH RESIDUAL WARM FRONTAL
SEGMENTS ON SW FRINGE OF ERODING COOL DOME.
THE SVR THREAT SHOULD DIMINISH THIS EVE AS HEIGHT RISES SPREAD E
FROM THE SRN PLNS TO THE LWR MS VLY...AND COLD FRONT CONTINUES TO
UNDERCUT STORMS.
...MID MS VLY/MIDWEST...
DESPITE AMPLE LARGE SCALE FORCING FOR ASCENT AND STRENGTHENING
DEEP WIND FIELD ASSOCIATED WITH AMPLIFYING UPR TROUGH... APPRECIABLE
LOW LVL DESTABILIZATION SEEMS UNLIKELY AHEAD OF COLD FRONT GIVEN
PREFRONTAL RAIN/CLOUDS. BUT COMBINATION OF WEAK ELEVATED
INSTABILITY AND STG WIND FIELD COULD SUPPORT A BAND OR TWO OF STORMS
WITH MARGINALLY SVR HAIL AND/OR CONVECTIVELY ENHANCED WINDS UNTIL
AROUND SUNSET.
...SW TX...
TSTMS MAY INCREASE EARLY WED OVER SW TX AND PERHAPS FAR SE NM AS LOW
LVL MOISTURE RETURNS NWWD ON WRN SIDE OF SHORTWAVE RDG. ABSENCE OF
UPR LVL FORCING FOR ASCENT SHOULD LIMIT OVERALL SVR THREAT...BUT
AMPLE SHEAR AND ELEVATED INSTABILITY WILL EXIST FOR A FEW STORMS
WITH SVR HAIL.
..CORFIDI/SMITH.. 10/06/2009
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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