SWODY1
SPC AC 220551
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT WED OCT 22 2008
VALID 221200Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS TODAY OVER PARTS OF ERN OK INTO
NERN TX...
...SYNOPSIS...
AMPLIFYING MIDLEVEL TROUGH OVER THE CNTRL PART OF THE NATION WILL
EVOLVE INTO A CLOSED LOW OVER KS AS STRONG MID AND UPPER-LEVEL JET
STREAKS DEVELOP DOWNSTREAM FROM THE MEAN TROUGH BASE OVER THE
CNTRL/SRN LOW PLAINS INTO THE OZARK PLATEAU. THIS EVOLUTION WILL
RESULT IN SIGNIFICANT HEIGHT FALLS /60-120 M PER 12 HR/ SPREADING
SEWD ACROSS KS/OK/TX. IN THE LOW LEVELS...SURFACE CYCLONE WILL
UNDERGO OCCLUSION OVER CNTRL/ERN KS AS SYNOPTIC SYSTEM BECOMES
INCREASINGLY VERTICALLY STACKED. MEANWHILE...ATTENDANT...STRONG
COLD FRONT WILL SURGE SEWD THROUGH THE SRN PLAINS AND EVENTUALLY
INTO THE LOWER MS VALLEY BY THURSDAY MORNING.
...CNTRL/SRN PLAINS INTO LOWER MS VALLEY...
A QUASI-LINEAR MCS /QLCS/ IS CURRENTLY EVOLVING ALONG COLD FRONT
OVER WRN KS INTO THE OK/TX PNHDLS AND THIS SYSTEM IS LIKELY TO BE
ONGOING AT THE ONSET OF THE FORECAST PERIOD FROM PARTS OF CNTRL/ERN
KS SWWD INTO WRN OK AND PERHAPS NWRN TX. 22/00Z REGIONAL SOUNDINGS
ACROSS TX INDICATE THAT AMBIENT...PRE-FRONTAL AIR MASS HAS MOISTENED
SOME OVER THE PAST 24 HOURS WITH DEWPOINTS NOW IN THE LOWER 60S AND
PW VALUES AROUND AN INCH. A SIMILAR TYPE BOUNDARY LAYER MOISTURE
PROFILE WILL LIKELY DEVELOP NWD THROUGH CNTRL AND ERN TX TODAY IN
ADVANCE OF COLD FRONT SURGING SEWD. HOWEVER...DESPITE THIS INCREASE
IN MOISTURE...CONVECTIVE INSTABILITY WILL REMAIN LIMITED /I.E.
MLCAPE LESS THAN 500-750 J PER KG/ DUE TO GENERALLY WEAK MIDLEVEL
LAPSE RATES.
AFTER SOME DIURNAL WEAKENING THROUGH THE MORNING...INCREASING
BOUNDARY LAYER MOISTURE BENEATH HEIGHT FALLS/DYNAMIC COOLING WILL
CONTRIBUTE TO REINTENSIFICATION OF QLCS BY AFTERNOON OVER ERN OK
INTO NERN TX. A FEW STRONG TO MARGINALLY SEVERE STORMS MAY EVEN
DEVELOP NWD ALONG OCCLUDING FRONTAL ZONE OVER ERN KS AS SLIGHT AIR
MASS DESTABILIZATION OCCURS WITHIN A STRONGLY SHEARED AND FORCED
ENVIRONMENT. WHILE SOME HAIL IS POSSIBLE...IT APPEARS THAT LOCALLY
DAMAGING WIND GUSTS WILL BE THE PRIMARY SEVERE WEATHER THREAT GIVEN
THE STRENGTHENING WIND FIELDS AND ANTICIPATED LINEAR MODE OF
CONVECTION.
QLCS IS LIKELY TO CONTINUE SEWD THROUGH THE ARKLATEX AND ERN TX
LATER THIS AFTERNOON INTO TONIGHT...AWAY FROM THE STRONGER DYNAMIC
FORCING AND VERTICAL SHEAR. WHILE STRONG WIND GUSTS WILL REMAIN
POSSIBLE...ANY MORE ORGANIZED SEVERE THREAT SHOULD TEND TO DIMINISH
WITH TIME DUE TO THE WEAKENING SHEAR AND INSTABILITY WITH SWD
EXTENT. LATE TONIGHT...BOUNDARY LAYER MOISTENING AND STRENGTHENING
LOW-LEVEL WAA MAY CONTRIBUTE TO A PRE-FRONTAL CLUSTER OF TSTMS OVER
THE LOWER MS VALLEY. WHILE THE LIMITED INSTABILITY SHOULD PRECLUDE
A SIGNIFICANT SEVERE WEATHER THREAT...THE INCREASING LOW-LEVEL
MOISTURE AND SHEAR MAY SUPPORT A COUPLE OF ROTATING STORMS CAPABLE
OF PERHAPS A BRIEF TORNADO OR GUSTY WINDS.
..MEAD/LEVIT.. 10/22/2008
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