SWODY1
SPC AC 131626
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1126 AM CDT SAT JUN 13 2009
VALID 131630Z - 141200Z
...THERE IS A MDT RISK OF SVR TSTMS LATER THIS AFTERNOON AND EVENING
OK/TX PANHANDLE INTO WRN OK/NWRN TX...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF CENTRAL AND
SOUTHERN PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF MS...AL...GA
AND THE FL PANHANDLE...
...SYNOPSIS...
LITTLE OVERALL CHANGE IN LARGE SCALE PATTERN AS TROUGH PERSIST OVER
WRN U.S...RIDGE ACROSS SRN PLAINS/LWR MS VALLEY AND TROUGH IN THE
NORTHEAST. COMPOSITE OF A FRONTAL ZONE/CONVECTIVE OUTFLOW BOUNDARIES
EXTENDS WWD FROM TN VALLEY THRU CENTRAL OK ACROSS TX PANHANDLE INTO
ERN NM. A VERY MOIST AND POTENTIALLY EXTREMELY UNSTABLE AIR MASS
RESIDES S OF SRN PLAINS PORTION OF SURFACE BOUNDARIES. ADDITIONALLY
LOW LEVEL MOISTURE RETURNING NWD E OF FRONT RANGE CENTRAL HI PLAINS
IN ADVANCE OF A SIGNIFICANT UPPER TROUGH CURRENTLY EJECTING FROM WRN
TROUGH POSITION.
...WRN OK INTO NWRN TX AND THE TX PANHANDLE...
WHILE THIS AREA WILL GENERALLY BY CAPPED THRU MID AFTERNOON UNDER
THE RIDGE POSITION...VERY STRONG HEATING ALONG AND S OF FRONTAL ZONE
WILL RAISE SFC TEMPS TO NEAR 100 F NWRN TX WHICH ALONG WITH
DEWPOINTS NEAR OF ABOVE 70F BOTH VICINITY AND N OF BOUNDARY AND TO
THE E OF WHERE DRY LINE IS ABLE TO MIX WILL PUT IN PLACE AN
EXTREMELY UNSTABLE AIR MASS WITH MLCAPES AOA 4500 J/KG. GIVEN THE
LACK OF AVAILABLE LARGE SCALE LIFT AS AREA IN THE RIDGE
POSITION...SURFACE BASED STORMS EXPECTED TO FORM IN LOW LEVEL
CONVERGENCE BOTH VICINITY E/W BOUNDARY AND THE INTERFACE OF THE
STRONGLY HEATED/STEEP LAPSE RATE ENVIRONMENT VICINITY N/S DRY LINE
WCENTRAL TX.
MOST FAVORED REGION FOR SUPERCELLS AND LARGE HAIL/WIND DAMAGE WILL
BE ALONG AND ON THE COOL SIDE OF E/W FRONTAL ZONE WHERE GREATEST LOW
LEVEL SHEAR WILL RESIDE. ADDITIONALLY SEVERE STORMS EXPECTED TO
DEVELOP IN UPSLOPE REGION NERN NM AS MOIST LOW LEVEL AIRMASS SPREADS
WWD. SUPERCELLS WOULD THEN LIKELY DEVELOP EWD ACROSS TX/OK PANHANDLE
BY THIS EVENING WITH POTENTIAL FOR VERY LARGE HAIL...AT LEAST
ISOLATED TORNADOES AS THIS AREA WILL HAVE A FAVORABLE VEERING LOW
LEVEL SHEAR ENVIRONMENT/LARGE HODOGRAPHS AND RELATIVELY LOW LFC/S.
HAVE SHIFTED THE ORIGINAL MDT TO THE N AND W BASED ON THESE
REASONINGS WITH MORE ISOLATED SEVERE STORMS EXPECTED WITH SWD EXTENT
INTO SWRN TX AS CAP WILL BE STRONGER UNDER RIDGE ALONG WITH WEAKER
SHEAR.
SEVERE STORMS DEVELOPING EWD ACROSS MDT RISK AREA THIS EVENING WILL
LIKELY FORM ONE OR MORE MCS/S IN RESPONSE TO FORECASTED INCREASE IN
THE LOW LEVEL JET TO 30-40KT AND ASSOCIATED WARM ADVECTION. THIS
WILL MAINTAIN A SEVERE THREAT INCLUDING DAMAGING WINDS/LARGE HAIL
E/NEWD ACROSS OK/SRN KS TONIGHT.
...CENTRAL HIGH PLAINS...
WITH LOW LEVEL MOISTURE RETURNING NWD IN ADVANCE OF UPPER TROUGH
LIFTING NEWD ACROSS CENTRAL ROCKIES THIS AFTERNOON...EXPECT MORE
THAN SUFFICIENT INSTABILITY AND SHEAR TO BE IN PLACE FOR SEVERE
STORM DEVELOPMENT TODAY AS FAR N AS ERN WY. AS 50 DEWPOINTS/STEEP
LAPSE RATES AND INCREASING SHEAR WITH MID LEVEL SWLY FLOW OF 40-50
KTS SPREADING ACROSS FRONT RANGE...SEVERE THUNDERSTORMS INCLUDING
SUPERCELLS WILL DEVELOP ALONG AND E OF FRONT RANGE BASED ON THESE
EXPECTED CONDITIONS NWD INTO SERN WY.
FURTHER W INTO CENTRAL WY...THE AIR MASS WILL DESTABILIZE AND
SUPPORT ACTIVE THUNDERSTORMS AHEAD OF UPPER TROUGH WHICH WILL
INCLUDE BOTH HAIL AND DAMAGING WINDS BY MID AFTERNOON. LOW LEVEL
SHEAR/MOISTURE WILL BE A LITTLE LESS FAVORABLE THAN FURTHER E...BUT
GIVEN THE LARGE SCALE ASCENT WITH TROUGH AT LEAST ISOLATED
SUPERCELLS ARE LIKELY.
...MS/AL/GA/FL...
SCATTERED THUNDERSTORMS ARE ONGOING THIS MORNING OVER PARTS OF
MS/AL. THIS ACTIVITY MAY INTENSIFY EARLY THIS AFTERNOON
AS DAYTIME HEATING DESTABILIZES THE AIRMASS. ISOLATED SEVERE STORMS
CAPABLE OF HAIL AND DAMAGING WINDS ARE EXPECTED THROUGH THE DAY AS
STORMS SPREAD EAST-SOUTHEASTWARD TOWARD GA/FL PANHANDLE.
...UPPER MS VALLEY...
STEEP LOW LEVEL LAPSE RATES...COOL TEMPERATURE PROFILES AND MARGINAL
INSTABILITY EXPECTED TO BE SUFFICIENT FOR A FEW STRONG/SEVERE
THUNDERSTORMS ALONG/AHEAD OF FRONT MOVING SEWD ACROSS UPPER MS
VALLEY THIS AFTERNOON. PRIMARY THREAT WILL BE HAIL/GUSTY WINDS.
..HALES/SMITH.. 06/13/2009
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