DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 251626
SWODY1
SPC AC 251623

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1023 AM CST MON FEB 25 2008

VALID 251630Z - 261200Z

..THERE IS A SLGT RISK OF SVR TSTMS MAINLY TONIGHT FROM THE
ARKLATEX EWD ACROSS MS/AL...

..SYNOPSIS...
MID LEVEL SHORTWAVE TROUGHS IN NM AND KS WILL PHASE TOGETHER BY LATE
AFTERNOON ACROSS OK/NRN TX...AND AID IN AMPLIFYING THE LARGE SCALE
TROUGH FROM THE CENTRAL/SRN PLAINS EWD ACROSS THE LOWER/MID MS
VALLEY REGION TONIGHT. ASSOCIATED SURFACE LOW...CURRENTLY LOCATED IN
NERN KS...IS FORECAST TO SHIFT RAPIDLY ESEWD AND INTO WRN KY BY
DAYBREAK TUESDAY. TRAILING COLD FRONT WILL MOVE THROUGH THE
CENTRAL/SRN PLAINS TODAY AND LOWER/MID MS VALLEY TONIGHT.

..LOWER MS VALLEY REGION...
OF INITIAL CONCERN FOR SEVERE STORMS IS LACK OF BOUNDARY LAYER
MOISTURE...AS DEWPOINTS WERE MOSTLY IN THE 40S AND LOWER 50S AS OF
MID MORNING. HOWEVER...AN AXIS OF MID 60S DEWPOINTS IN SRN TX IS
EXPECTED TO SURGE NEWD INTO THE ARKLATEX REGION BY LATE TODAY...IN
RESPONSE TO STRONG SURFACE PRESSURE FALLS. THE INCREASING BOUNDARY
LAYER MOISTURE COMBINED WITH 7-8C/KM MID LEVEL LAPSE RATES WILL
RESULT IN MLCAPE VALUES FROM 1000-1500 J/KG IN A NARROW CORRIDOR
FROM THE MIDDLE TX COAST NEWD TO THE ARKLATEX BY EVENING.

THE INITIALLY SHALLOW MOIST BOUNDARY LAYER AND STRONG CONVECTIVE
INHIBITION ASSOCIATED WITH THE ELEVATED MIXED LAYER WILL LIKELY
DELAY CONVECTIVE INITIATION UNTIL AROUND 00Z. THEREAFTER...AS THE
STRONGER LARGE SCALE LIFTING SPREADS EWD...CONVECTION IS EXPECTED TO
DEVELOP IN THE ARKLATEX AREA...AND THEN SPREAD QUICKLY EWD OVERNIGHT
ACROSS AR/NRN LA/MS/TN/AL.

LOW-LEVEL JET NEAR 50 KT AND MID LEVEL WSWLY FLOW OF 70-90 KT WILL
CONTRIBUTE TO STRONG LOW/DEEP VERTICAL SHEAR IN THE WARM SECTOR. THE
INITIAL CONVECTION IN THE ARKLATEX MAY CONSIST OF SUPERCELLS WITH AN
ATTENDANT THREAT FOR A COUPLE OF TORNADOES...DAMAGING WINDS...AND
LARGE HAIL.

DESPITE THE LOSS OF DAYTIME HEATING ...LOW-LEVEL MOISTENING AND
FORCING ASSOCIATED WITH THE SURFACE FRONT SHOULD BE SUFFICIENT TO
MAINTAIN THUNDERSTORMS OVERNIGHT. THE SEVERE THREAT IS EXPECTED TO
EVOLVE TO A MORE DAMAGING WIND THREAT OVERNIGHT ACROSS PORTIONS OF
TN/MS/AL...AS A LINEAR CONVECTIVE SYSTEM EVOLVES ALONG THE COLD
FRONT.

.IMY.. 02/25/2008

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