SWODY1
SPC AC 131600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1100 AM CDT SUN SEP 13 2009
VALID 131630Z - 141200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF ERN MT...
...THERE IS A SLGT RISK OF SVR TSTMS CENTRAL GULF COAST REGION...
...ERN MT...
COMPACT UPPER LOW OVER SCENTRAL MT ATTM IS HEADING BACK N AGAIN INTO
CANADA BY 12Z MON. INITIALLY ENVIRONMENT NOT CONDUCIVE FOR STRONG
CONVECTION...BUT BY THIS EVENING COMBINATION OF UPPER COLD
POOL...40KT SSELY LLJ TRANSPORTING LOW LEVEL MOISTURE INTO ERN
MT...AND STRONG SURFACE HEATING E OF UPPER LOW WILL PUT IN PLACE
PARAMETERS FOR A FEW SEVERE THUNDERSTORMS. WITH LAPSE RATES IN
EXCESS OF 7C/KM AND MLCAPES APPROACHING 1000 J/KG BY LATER THIS
AFTERNOON...SURFACE BASED CONVECTION SHOULD INCREASE NEWD IN
FAVORABLE SHEAR ENVIRONMENT FOR NOT ONLY ORGANIZED
THUNDERSTORMS...BUT POTENTIALLY A FEW SUPERCELLS. PRIMARY THREAT
GIVEN THE COLD AIR ALOFT AND MARGINAL LOW LEVEL MOISTURE WILL BE
LARGE HAIL. HOWEVER WITH ANY SUPERCELL DEVELOPMENT THERE WILL BE
POTENTIAL FOR A BRIEF TORNADO AND LARGER HAIL. ACTIVITY SHOULD
DEVELOP NWD BY LATE EVENING INTO CANADA WITH THREAT ENDING OVER ERN
MT.
...CENTRAL GULF COAST...
SETUP OVER THE WRN/CNTRL GULF CST REGION WILL REMAIN SIMILAR TO THAT
ON SAT. HOWEVER A MORE DECIDED NWD ADVANCE OF THE W/E WARM
FRONT NOW OVER THE NRN GULF RELATIVE TO SAT. BY LATE THIS AFTN THE
BOUNDARY SHOULD EXTEND FROM NEAR LFK EWD THROUGH CNTRL LA INTO S
CNTRL MS. ADVANCE OF THE FRONT WILL ALLOW VERY RICH MOISTURE /SFC
DEWPOINTS IN THE MID 70S F AND PW AOA 2.00 INCHES/ TO OVERSPREAD
AREAS ALONG AND N OF THE I-10 CORRIDOR.
MID LVL SSWLY WINDS WILL STRENGTHEN THROUGH THE DAY...WITH 700-500
MB FLOW EXPECTED TO REACH 25-30 KTS. LOW-LVL WINDS...HOWEVER...
SHOULD REMAIN FAIRLY WEAK AS ANY DEEPENING OF SFC LOW NOW OVER SE TX
IS EXPECTED TO BE MINIMAL. NEVERTHELESS...COMBINATION OF SUSTAINED
WAA WITH RICH MOISTURE AND LOW-LVL VEERING WIND PROFILES WILL FAVOR
THE DEVELOPMENT OF NUMEROUS STORM CLUSTERS NEAR WARM FRONT. THESE
MAY EXHIBIT PERIODIC LOW LVL ROTATION...AND COULD POSE A THREAT FOR
A FEW TORNADOES AND/OR STG WIND GUSTS.
..HALES/GRAMS.. 09/13/2009
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