The SPC is forecasting ...severe thunderstorms expected over parts of the southern plains later today through thursday morning.... Please read the latest public statement about this event.
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SPC AC 090557 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1257 AM CDT WED APR 09 2008 VALID 091200Z - 101200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SRN OK AND ADJACENT N TX... ...THERE IS A SLGT RISK OF SVR TSTMS OVER A LARGE PORTION OF THE CENTRAL PLAINS AND EWD TOWARD THE LOWER AND MID MS VALLEY... ...SYNOPSIS... HIGHLY-AMPLIFIED UPPER PATTERN IS FORECAST DAY 1...AS STRONG UPPER TROUGH MOVES EWD ACROSS THE ROCKIES AND INTO THE CENTRAL AND SRN HIGH PLAINS DURING THE SECOND HALF OF THE PERIOD. AT THE SURFACE...COLD FRONT MOVING EWD ACROSS THE MIDWEST/OH VALLEY WILL TRAIL WSWWD ACROSS THE MID MS VALLEY AND INTO TX EARLY IN THE PERIOD. THIS FRONT SHOULD RETURN SLOWLY NWD AS A WARM FRONT...AS LEE CYCLOGENESIS OCCURS OVER THE CENTRAL AND SRN HIGH PLAINS AHEAD OF THE APPROACHING UPPER TROUGH -- DRIVING AN INCREASE IN SLY BOUNDARY-LAYER FLOW ACROSS THE TX WARM SECTOR. DURING THE SECOND HALF OF THE PERIOD...A MORE FOCUSED SURFACE LOW SHOULD BEGIN TO CONSOLIDATE OVER W TX AND THEN MOVE NEWD TOWARD OK WITH TIME...WITH A TRAILING COLD FRONT MOVING EWD ACROSS THE WRN HALF OF TX THROUGH THE END OF THE PERIOD. ...SRN PLAINS EWD TOWARD THE LOWER AND MID MS VALLEY... VERY COMPLEX SCENARIO -- BUT A POTENTIALLY HIGHER-END SEVERE WEATHER EPISODE -- EXISTS FOR THE DAY 1 PERIOD. THUNDERSTORMS WILL LIKELY BE ONGOING AT THE START OF THE PERIOD INVOF THE SURFACE FRONT FROM NERN TX ENEWD INTO THE MID MS VALLEY. STORMS SHOULD ALSO BE INCREASING IN COVERAGE ACROSS PARTS OF THE WRN HALF OF TX -- ESPECIALLY THE PANHANDLE AND SOUTH PLAINS REGION -- AS SELY LOW-LEVEL JET PROVIDES A COMBINATION OF FAVORABLE UPSLOPE FLOW AND WARM/THETA-E ADVECTION INTO THIS REGION. STORM DEVELOPMENT/MAINTENANCE WILL BE AIDED BY A WEAK LEAD WAVE EJECTING ACROSS THIS REGION EARLY IN THE PERIOD IN ADVANCE OF THE MAIN UPPER TROUGH. THE MAJORITY OF THIS CONVECTION WILL REMAIN ELEVATED N OF THE MAIN SURFACE BOUNDARY...BUT WITH STEEP LAPSE RATES ALOFT AND 40 KT SWLY MID-LEVEL FLOW SPREADING ACROSS THE AREA...ROTATING STORMS AND AN ASSOCIATED HAIL THREAT CAN BE EXPECTED. THE CONVECTION WILL SPREAD ACROSS SRN KS/OK/N TX THROUGH THE DAY...AND WHILE HAIL SHOULD REMAIN THE PRIMARY THREAT...STORMS REDEVELOPING NEAR THE SRN FRINGE OF THE LARGER CONVECTIVE CLUSTER MAY BECOME SURFACE-BASED INTO THE AFTERNOON AS THE WARM FRONT -- AND DESTABILIZING WARM SECTOR -- LIFT SLOWLY NWD. WHILE DETAILS REGARDING THIS POSSIBLE SURFACE-BASED THREAT REMAIN DIFFICULT TO PIN DOWN ATTM...INCREASING MID-LEVEL FLOW SPREADING ACROSS THE MODERATELY-UNSTABLE WARM SECTOR WILL RESULT IN AN ENVIRONMENT INCREASINGLY SUPPORTIVE OF VIGOROUS SUPERCELLS. THUS...IT APPEARS THAT SOME THREAT FOR DAMAGING WINDS AND/OR TORNADOES WILL EVOLVE DURING THE AFTERNOON ACROSS PARTS OF CENTRAL AND N TX AND PERHAPS INTO SRN OK WITH TIME. THE AFOREMENTIONED CONVECTIVE AREA SHOULD GENERALLY SPREAD EWD WITH TIME ACROSS ERN OK/NERN TX INTO AR/LA...WITH PERHAPS MORE ISOLATED SEVERE STORMS LINGERING OVER CENTRAL AND WRN OK/CENTRAL AND NRN TX ON WRN FRINGES OF THE CONVECTIVE CLUSTER. BY LATE AFTERNOON/EARLY EVENING...ANY LINGERING STORMS OVER TX/OK SHOULD BECOME PART OF A MORE WIDESPREAD AREA OF VIGOROUS STORM DEVELOPMENT...AS THE UPPER TROUGH BEGINS TO AFFECT THE SRN HIGH PLAINS. THE UPPER FEATURE WILL BE ACCOMPANIED BY STRONG FLOW ALOFT -- INCLUDING 60 KT FLOW AT H7 AND 80 KT AT H5 -- WHICH WILL BEGIN OVERSPREADING THE SRN PLAINS FROM EVENING ONWARD ATOP AN INTENSIFYING LOW-LEVEL JET. WITH SHEAR BECOMING INCREASINGLY-FAVORABLE FOR POTENT SUPERCELLS...DEVELOPING CONVECTION WILL LIKELY POSE A THREAT FOR SIGNIFICANT SEVERE WEATHER -- INCLUDING LARGE HAIL...DAMAGING WINDS...AND THE POTENTIAL FOR DAMAGING TORNADOES. ATTM...IT APPEARS THAT THE GREATEST SEVERE THREAT WILL EXIST ACROSS PARTS OF SRN OK AND N TX -- BOTH ON THE SRN FRINGE OF THE INITIAL CONVECTIVE CLUSTER AND THEN LATER WITH THE STORMS DEVELOPING DURING THE SECOND HALF OF THE PERIOD AHEAD OF THE MAIN TROUGH. WHILE THE POTENTIAL FOR SIGNIFICANT SEVERE WEATHER WILL EXIST OVER THIS AREA DURING THE FIRST HALF OF THE PERIOD...THE GREATEST THREAT FOR DAMAGING WINDS AND/OR SIGNIFICANT TORNADOES SHOULD EXIST FROM EVENING ONWARD AS THE UPPER TROUGH EMERGES. ..GOSS.. 04/09/2008 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z