SWODY1
SPC AC 130554
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1254 AM CDT THU MAR 13 2008
VALID 131200Z - 141200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER ERN PARTS OF THE SRN
PLAINS INTO THE LOWER MS VALLEY...
..SYNOPSIS...
PROGRESSIVE UPPER PATTERN WILL PREVAIL THURSDAY WITH PRIMARY FEATURE
OF INTEREST BEING THE SHORTWAVE TROUGH CURRENTLY MOVING INTO THE SRN
ROCKIES. THIS FEATURE WILL MOVE ESEWD INTO THE SRN PLAINS DURING THE
DAY THEN INTO THE LOWER MS VALLEY THURSDAY EVENING. WRN END OF FRONT
NOW EXTENDING FROM THE GREAT LAKES AREA SWWD INTO NWRN OK AND THE TX
PANHANDLE WILL TEMPORARILY STALL AS WEAK SURFACE WAVE DEVELOPS OVER
OK. DRYLINE SETUP ACROSS CNTRL TX AND EXTEND NWD TO THE SURFACE LOW
IN OK...BUT WILL BE OVERTAKEN BY SEWD ADVANCING PACIFIC FRONT
ACCOMPANYING THE SHORTWAVE TROUGH. THE FRONT WILL ADVANCE SEWD AND
EXTEND FROM NRN AR SWWD THROUGH ERN TX BY THE END OF THE PERIOD.
..ERN OK AND ERN TX THROUGH THE LOWER MS VALLEY...
BOUNDARY LAYER OVER THE GULF IS STILL IN THE PROCESS OF MODIFICATION
WITH DEWPOINTS ONLY AROUND 60 NEAR THE COAST WITH 50S FARTHER INLAND
OVER THE TX COAST. LOW LEVEL MOISTURE RETURN THROUGH THE SRN PLAINS
WILL THEREFORE BE SOMEWHAT LIMITED. SLY LOW LEVEL JET DEVELOPING IN
ADVANCE OF THE SHORTWAVE TROUGH WILL ADVECT MODIFIED CP THROUGH ERN
TX...ERN OK AND INTO THE LOWER MS VALLEY WITH DEWPOINTS RANGING FROM
THE 50S IN ERN OK AND AR TO THE LOWER 60S FARTHER SW ACROSS ERN TX
AND PARTS OF LA THURSDAY EVENING. THE MOISTURE WILL RETURN NWD
BENEATH STEEPENING MID LEVEL LAPSE RATES AND COLD AIR ALOFT WITH
-16C TO -20C AT 500 MB. THIS WILL CONTRIBUTE TO AN AXIS OF 1000 TO
1500 J/KG MLCAPE FROM ERN TX...ERN OK DURING THE AFTERNOON. THE
ATMOSPHERE WILL DESTABILIZE OVER THE LOWER MS VALLEY DURING THE
EVENING AS THE MOIST AXIS AND STEEPER MID LEVEL LAPSE RATES ADVECT
EWD.
PRIMARY ZONE OF THUNDERSTORM DEVELOPMENT WILL LIKELY OCCUR DURING
THE LATE AFTERNOON OVER PARTS OF ERN OK NEAR TRIPLE POINT REGION AND
WITHIN ZONE OF STRONGER LOW LEVEL FORCING AND CONVERGENCE ON NOSE OF
THE LOW LEVEL JET. STORMS MAY DEVELOP SWD ALONG DRYLINE INTO NERN
TX. THIS ACTIVITY WILL SUBSEQUENTLY SHIFT EWD INTO ARKANSAS DURING
THE EVENING. BULK SHEAR PROFILES WILL BE SUPPORTIVE OF
SUPERCELLS...BUT OWING TO EXPECTED FAIRLY LARGE TEMPERATURE-DEWPOINT
SPREADS...THE MAIN THREATS SHOULD BE LARGE HAIL AND ISOLATED
DAMAGING WIND.
FARTHER SOUTH INTO ERN TX...THE THREAT IS MORE CONDITIONAL DUE TO
LIKELIHOOD OF A STRONGER CAP. HOWEVER...INSTABILITY WILL BE STRONGER
IN THIS REGION. CURRENT THINKING IS THAT A FEW STORMS MAY DEVELOP
DURING THE EVENING FROM EXTREME ERN TX OR INTO THE LOWER MS VALLEY
ALONG ERN FRINGE OF EML WITHIN ZONE OF HEIGHT FALLS AND LOW LEVEL
WARM ADVECTION. BULK SHEAR WILL SUPPORT SUPERCELLS WITH LARGE HAIL
AND DAMAGING WIND THE MAIN THREATS. THE LOW LEVEL JET WILL INCREASE
DURING THE EVENING WITH FAIRLY LARGE LOW LEVEL HODOGRAPHS.
HOWEVER...LOW LEVEL MOISTURE RETURN WILL REMAIN SOMEWHAT
LIMITED...AND WITH THE ONSET OF NOCTURNAL COOLING THE BOUNDARY LAYER
WILL PROBABLY BECOME INCREASINGLY DECOUPLED AFTER DARK.
.DIAL.. 03/13/2008
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