SPC AC 091746
DAY 2 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
1246 PM CDT FRI MAY 09 2008
VALID 101200Z - 111200Z
...THERE IS A MDT RISK OF SVR TSTMS FROM PARTS OF ERN OK...NERN
TX...AR...NRN LA...NRN MS AND NW AL...
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE SRN
PLAINS...LOWER MS VALLEY AND SERN STATES...
CORRECTED FOR OUTLOOK GRAPHIC
...ERN OK/TX THROUGH THE CNTRL GULF STATES...
NRN STREAM SHORTWAVE TROUGH NOW OVER THE NRN ROCKIES IS FORECAST TO
AMPLIFY SEWD INTO THE CNTRL PLAINS REGION...POSSIBLY PHASING WITH
SRN STREAM SPEED MAX CURRENTLY NEAR BAJA CALIFORNIA THAT WILL
ADVANCE EWD THROUGH TX. FRONTAL BOUNDARY WILL LIFT NWD THROUGH OK
AND THE LOWER MS VALLEY EARLY SATURDAY IN RESPONSE TO DEVELOPING LEE
TROUGH AND INTENSIFYING LOW LEVEL JET DOWNSTREAM FROM UPPER TROUGH.
RECENT OBSERVATIONS SHOW DEWPOINTS IN THE UPPER 60S TO AROUND 70
FROM SERN TX INTO THE LOWER MS VALLEY REGION. OBSERVED 12Z SOUNDINGS
INDICATED THAT THIS MOIST LAYER IS QUITE SHALLOW. THIS RAISES
CONCERN THAT MODELS MAY BE OVERESTIMATING QUALITY OF MOISTURE THAT
WILL BE AVAILABLE SATURDAY. HOWEVER...RICHER BOUNDARY LAYER LIKELY
RESIDES OFFSHORE AND WILL ADVECT NWD DURING THE DAY WITH AT LEAST
LOW TO MID 60S DEWPOINTS POSSIBLE IN MODERATE RISK AREA. PLUME OF
STEEP MID LEVEL LAPSE RATES WILL ADVECT EWD OVER THE MOIST
AXIS...CONTRIBUTE TO STRONG INSTABILITY DURING THE AFTERNOON WITH
MLCAPE FROM 2000 TO 3000 J/KG POSSIBLE.
INITIAL STORMS WILL BE POSSIBLE NORTH OF WARM FRONT OVER PARTS OF OK
AND LOWER MS VALLEY EARLY FRIDAY WITHIN ZONE OF WARM ADVECTION AND
ISENTROPIC LIFT. STEEP MID LEVEL LAPSE RATES...MODERATE MUCAPE AND
EFFECTIVE SHEAR SUFFICIENT FOR UPDRAFT ROTATION SUGGEST THIS
ACTIVITY WILL POST A THREAT FOR LARGE HAIL. THIS ACTIVITY WILL LIFT
NE DURING THE MORNING ALLOWING THE WARM SECTOR TO DESTABILIZE IN ITS
WAKE. BY MID AFTERNOON A DRYLINE IS EXPECTED TO EXTEND FROM SURFACE
LOW IN CNTRL OK SWD THROUGH N CNTRL AND CNTRL TX. A WARM FRONT WILL
EXTEND FROM THE LOW EWD THROUGH THE LOWER MS VALLEY AND SERN STATES.
COLD FRONT WILL EXTEND FROM THE CNTRL PLAINS SWWD THROUGH NWRN OK
AND NW TX. HEIGHT FALLS AND ASCENT ASSOCIATED WITH AMPLIFYING UPPER
TROUGH WILL PROBABLY RESULT IN FAVORABLE ENVIRONMENT FOR STORMS TO
INITIATE ALONG THE DRYLINE AS IT MIXES EWD THROUGH CNTRL AND ERN OK.
OTHER STORMS MAY DEVELOP FARTHER SOUTH ALONG THE DRYLINE INTO NCNTRL
OR NERN TX. STRONG DEEP LAYER SHEAR ATTENDING THE AMPLIFYING UPPER
TROUGH AND SPEED MAX MOVING EWD THROUGH TX WILL SUPPORT SUPERCELLS.
BEST LOW LEVEL HODOGRAPHS FOR LOW LEVEL MESOCYCLONES ARE FORECAST
FROM ERN OK INTO AR WHERE THE INTENSIFYING LOW LEVEL JET WILL
INTERSECT THE WARM FRONT. STORMS MOVING INTO THIS REGION MAY BECOME
CAPABLE OF PRODUCING VERY LARGE HAIL AND A FEW TORNADOES. ADDITIONAL
STORMS MAY DEVELOP ALONG THE COLD FRONT AS IT ADVANCES SEWD THROUGH
OK AND THE LOWER MS VALLEY DURING THE EVENING. OVERNIGHT STORMS MAY
EVENTUALLY EVOLVE INTO ONE OR MORE MCSS OVER THE LOWER MS VALLEY AND
SPREAD EAST THROUGH THE SERN STATES. INTENSIFYING WSWLY LOW LEVEL
JET AND STRONG UNIDIRECTIONAL SHEAR SUGGEST PRIMARY THREAT MAY
TRANSITION TO WIDESPREAD DAMAGING WIND...THROUGH ISOLATED TORNADOES
AND HAIL WILL REMAIN POSSIBLE.
..DIAL.. 05/09/2008
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0800Z
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