...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS ARKLATEX REGION TO
LOWER MS VALLEY...
...SYNOPSIS...
IN MIDDLE-UPPER LEVELS...SPLIT-FLOW PATTERN FCST TO PERSIST WELL
BEYOND THIS PERIOD. RIDGING WILL EXTEND SWD ACROSS ND FROM
ANTICYCLONE CENTERED OVER NERN SK...WHILE CONTINUOUS/QUASI-ZONAL
CURRENT COVERS MUCH OF CONUS FROM MIDDLE-SRN ATLANTIC COAST WWD
ACROSS CENTRAL/SRN ROCKIES. WELL-DEFINED CYCLONE -- NOW EVIDENT IN
MOISTURE CHANNEL IMAGERY OFFSHORE ORE -- IS FCST TO MOVE INLAND
EARLY THIS PERIOD. THIS FEATURE THEN SHOULD QUICKLY DEAMPLIFY INTO
WEAKENING OPEN-WAVE TROUGH OVER NRN ROCKIES...WHILE SECOND CYCLONE
DEVELOPS OFFSHORE PAC NW. SHORTWAVE TROUGH -- NOW MOVING INLAND
CENTRAL/NRN CA -- IS FCST TO MOVE EWD ACROSS GREAT BASIN AND CENTRAL
ROCKIES TO CENTRAL HIGH PLAINS BY 26/12Z. MEANWHILE...DOWNSTREAM
SHORTWAVE OVER CENTRAL PLAINS WILL MOVE EWD AND WEAKEN CONSIDERABLY
ACROSS CENTRAL APPALACHIANS TODAY...AMIDST CONFLUENT FLOW ALOFT
ASSOCIATED WITH CYCLONE OVER LOWER ST LAWRENCE VALLEY REGION.
AT SFC...WEAK NW TX/SWRN OK LOW IS EXPECTED ALONG WARM FRONTAL ZONE
EARLY IN PERIOD...WITH FRONT ESEWD ACROSS ARKLATEX TO CENTRAL/SRN
LA. FRONT SHOULD LIFT NWD INTO SERN OK AND SRN AR BY
26/00Z...EXTENDING WNWWD ACROSS SRN TX PANHANDLE REGION. BY THAT
TIME...DRYLINE SHOULD EXTEND FROM SERN OK SWWD ACROSS N-CENTRAL TX
TO SRN HILL COUNTRY...THEN RETREAT SLIGHTLY WWD DURING EVENING.
ANOTHER SFC LOW MAY DEVELOP OVERNIGHT ALONG FRONT INVOF SWRN OK/NW
TX AND MOVE EWD...WITH RELATED VEERING OF SFC WINDS TO ITS S AND SW
RESULTING IN EWD OSCILLATION OF DRYLINE AGAIN BEFORE 26/12Z.
...ARKLATEX REGION TO LOWER MS VALLEY...
AREA OF STG-SVR TSTMS IS EXPECTED TO DEVELOP...EXPAND AND MOVE EWD
FROM NE TX/SERN OK/SWRN AR AREA DURING EVENING...AMIDST INCREASING
LOW-LEVEL MOISTURE AND FAVORABLE DEEP-LAYER SHEAR PROFILES TO
SUPPORT SVR RISK. SUPERCELLS WITH LARGE HAIL AND SVR GUSTS ARE
POSSIBLE...AND THREAT FOR TORNADOES ALSO MAY EXIST INVOF
WARM-FRONTAL ZONE.
PROGS ARE IN VERY STG AGREEMENT REGARDING GENERAL EVOLUTION/LOCATION
OF SCENARIO...HOWEVER TIMING OF INITIATION REMAINS QUITE
UNCERTAIN...ESPECIALLY POTENTIAL FOR DIURNAL/SFC-BASED DEVELOPMENT
BEFORE 00Z. THIS IS BECAUSE OF STG CAPPING RELATED TO
ANTECEDENT/ELEVATED MIXED LAYER...COMBINED WITH ONLY SUBTLE/SHALLOW
WARM-FRONTAL LIFT AND LACK OF SIGNIFICANT MID-UPPER PERTURBATION
NEARBY. THIS REGION WILL BE TOO REMOVED FROM GREAT BASIN/CENTRAL
ROCKIES SHORTWAVE TROUGH TO EXPERIENCE DIRECT EFFECTS.
HOWEVER...BROAD/LOW-LEVEL WAA REGIME ALREADY IN PLACE OUGHT TO
STRENGTHEN OVERNIGHT ACROSS LOWER MS VALLEY REGION...RESULTING IN
INCREASING THETAE WITH TIME FOR INFLOW PARCELS IN AND N OF SFC
WARM-FRONTAL ZONE. TIME WINDOW FOR SFC-BASED CONVECTION SHOULD
EXIST DURING EVENING NEAR WARM FRONT BEFORE SUBSTANTIAL SFC
COOLING...AS LOW-LEVEL HODOGRAPH EXPANDS BENEATH STRENGTHENING LLJ.
THIS WILL BOOST SRH AND TORNADO POTENTIAL FOR SEVERAL HOURS...BEFORE
ACTIVITY MOVES EWD INTO MORE STABLE AIR MASS. ADDITIONAL
DEVELOPMENT MAY OCCUR OVERNIGHT IN EARLIER STORM GENESIS REGION OF
SERN OK/NE TX...MAINTAINING SVR THREAT BEHIND INITIAL ACTIVITY.
...WRN OZARKS REGION...
CLUSTER OF SCATTERED/ELEVATED TSTMS MAY BE ONGOING EARLY IN PERIOD
OVER PORTIONS NERN OK/SERN KS...ROOTED IN 750-850 MB LAYER BASED ON
RUC/ETA-KF FCST SOUNDINGS. ALTHOUGH BUOYANCY IS EXPECTED TO BE
RATHER UNSPECTACULAR...WITH MUCAPE 400-800 J/KG...40-50 KT EFFECTIVE
SHEAR INDICATES CONVECTION MAY BE ORGANIZED ENOUGH FOR MRGL HAIL
POTENTIAL. THIS ACTIVITY SHOULD WEAKEN THROUGH MID-LATE MORNING AS
IT MOVES EWD OVER AR/MO OZARKS AND INITIALLY SUPPORTIVE LLJ
DIMINISHES.
..EDWARDS/DEAN.. 03/25/2011
CLICK TO GET WUUS01 PTSDY1 PRODUCT