SWODY1
SPC AC 150443
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1143 PM CDT WED OCT 14 2009
VALID 151200Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF ERN TX INTO THE
CNTRL GULF STATES...
...SYNOPSIS...
CURRENT QUASI-ZONAL FLOW REGIME WILL UNDERGO AMPLIFICATION AS A
SERIES OF MIDLEVEL IMPULSES SERVE TO ESTABLISH A LONG WAVE TROUGH E
OF THE ROCKIES. THIS EVOLUTION WILL RESULT IN THE MOST SIGNIFICANT
HEIGHT FALLS/DYNAMIC FORCING FOR ASCENT DEVELOPING SEWD THROUGH THE
OH AND TN VALLEYS INTO PARTS OF THE CNTRL AND ERN GULF STATES. AT
THE SURFACE...COLD FRONT ATTENDANT TO AMPLIFYING UPPER TROUGH WILL
PUSH SEWD FROM THE ARKLATEX AND MID SOUTH THROUGH THE GULF COAST
REGION. THIS BOUNDARY WILL BE THE PRIMARY FOCUS FOR STRONG TO
SEVERE TSTM DEVELOPMENT THIS AFTERNOON INTO TONIGHT.
...ERN TX EWD INTO THE CNTRL GULF STATES...
15/00Z SOUNDINGS AND CURRENT GOES SOUNDER AND GPS PW DATA INDICATE A
MOIST LOW-LEVEL AIR MASS IN PLACE FROM CNTRL TX INTO THE LOWER MS
VALLEY WITH DEWPOINTS IN THE UPPER 60S TO MID 70S AND PW VALUES FROM
1.75-2.25 INCHES. REGIONAL VWP/PROFILER DATA INDICATE THAT
LOW-LEVEL WIND FIELDS ARE INCREASING WHILE VEERING TO A WSWLY
DIRECTION FROM THE SRN PLAINS INTO OZARKS AND LOWER MS VALLEY IN
RESPONSE TO EWD TRANSLATION OF LEAD SHORT WAVE TROUGH INTO THE MID
MS VALLEY. THESE LOW-LEVEL TRAJECTORIES ARE FORECAST TO BE
MAINTAINED TODAY WITHIN PRE-FRONTAL WARM SECTOR...ALLOWING MOIST AIR
MASS TO SPREAD EWD THROUGH THE CNTRL GULF STATES. MID LEVEL LAPSE
RATES WILL REMAIN WEAK...BUT THIS MOISTURE IN CONJUNCTION WITH
DAYTIME HEATING ARE EXPECTED TO CONTRIBUTE TO A MODERATELY UNSTABLE
AIR MASS BY AFTERNOON /PARTICULARLY ACROSS THE SLIGHT RISK AREA/
WHERE MLCAPE WILL APPROACH 1500-2500 J/KG.
CLUSTERS OF TSTMS ARE EXPECTED TO BE ONGOING AT THE ONSET OF THE
FORECAST PERIOD INVOF SURFACE FRONT FROM THE ARKLATEX INTO THE LOWER
MS VALLEY. THIS ACTIVITY IS FORECAST TO INCREASE IN COVERAGE AND
INTENSITY THROUGH THE DAY AS INCREASED HEIGHT FALLS AND FRONTAL
CONVERGENCE INTERACT WITH DESTABILIZING WARM SECTOR. WHILE
NEAR-GROUND SHEAR WILL NOT BE PARTICULARLY STRONG OWING TO VEERED
LOW-LEVEL WINDS IN WARM SECTOR...FORECAST WIND PROFILES ALONG FRONT
INDICATE RELATIVELY STRONG MID AND HIGH-LEVEL FLOW...RESULTING IN
40-50 KT OF DEEP-LAYER SHEAR. AS SUCH...SETUP APPEARS TO FAVOR THE
DEVELOPMENT OF EMBEDDED BOWING STRUCTURES CAPABLE OF MAINLY DAMAGING
WINDS THROUGH THIS EVENING.
..MEAD/GRAMS.. 10/15/2009
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