The SPC is forecasting ...a significant severe weather outbreak...including the possibility of long-track and violent tornadoes...are expected over parts of the central plains this afternoon and tonight.... Please read the latest public statement about this event.
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SPC AC 052004 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0304 PM CDT SAT MAY 05 2007 VALID 052000Z - 061200Z ...THERE IS A HIGH RISK OF SVR TSTMS ACROSS PARTS OF CENTRAL NEB AND CENTRAL KS... ...THERE IS A MDT RISK OF SVR TSTMS FROM SRN SD SWD INTO THE NERN TX PANHANDLE/NWRN OK... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE PORTION OF THE PLAINS STATES... ...NRN PLAINS SWD INTO NWRN OK/NERN TX PANHANDLE... WIDESPREAD SEVERE WEATHER EPISODE IS NOW UNDERWAY...WITH SEVERE/SUPERCELL STORMS ONGOING FROM SD SWD INTO NWRN OK. THIS INITIAL CONVECTION APPEARS TO BE ASSOCIATED WITH A STRONG VORT MAX NOW MOVING INTO THE NEB PANHANDLE. AIRMASS AHEAD OF THIS FEATURE AND ASSOCIATED DRYLINE...FROM CENTRAL NEB SWD ACROSS KS/WRN OK...HAS BECOME STRONGLY UNSTABLE...WITH MEAN-LAYER CAPE GENERALLY 1500 TO 3000 J/KG AHEAD OF INCREASINGLY-WIDESPREAD STORMS. ALONG WITH FAVORABLE INSTABILITY...VERY STRONG DEEP-LAYER WIND FIELD HAS SPREAD INTO THE PLAINS...WITH SSWLY MID-LEVEL JET IN EXCESS OF 90 KT ACROSS WRN KS. DESPITE THE MERIDIONAL COMPONENT TO THE MID-LEVEL FLOW FIELD...SSELY FLOW AT LOW LEVELS VEERING RAPIDLY AND INCREASING IN MAGNITUDE WITH HEIGHT IS RESULTING IN SHEAR PROFILES FAVORABLE FOR STRONG ROTATION -- BOTH AT LOW AND MID LEVELS. ONGOING SUPERCELLS WITHIN THIS VERY FAVORABLE KINEMATIC AND THERMODYNAMIC ENVIRONMENT HAVE ALREADY PRODUCED LARGE HAIL...LOCALLY-DAMAGING WINDS...AND A FEW TORNADOES -- WITH SEVERAL LONG-LIVED SUPERCELLS ALREADY OBSERVED. EXPECT THIS TREND TO CONTINUE...AS AIRMASS DESTABILIZES FURTHER THROUGH THE AFTERNOON. ALONG WITH CONTINUED LARGE HAIL/DAMAGING WINDS...SEVERAL TORNADOES ARE ALSO EXPECTED -- INCLUDING THE THREAT THAT A FEW WILL BE SIGNIFICANT/LONG-LIVED. WHILE INITIAL STORMS ONGOING ACROSS CENTRAL PORTIONS OF KS AND NEB WILL CONTINUE MOVING EWD WITH TIME...ADDITIONAL CONVECTIVE DEVELOPMENT BEHIND THESE STORMS/INVOF DRYLINE IS EXPECTED AS ADDITIONAL SHORT-WAVE DISTURBANCES ALOFT ROTATE CYCLONICALLY NEWD/NNEWD ACROSS THIS REGION WITHIN LARGER-SCALE CYCLONIC FLOW. SEVERE THREAT IS FORECAST TO CONTINUE THROUGH THE OVERNIGHT HOURS. ...WRN OK/ERN TX PANHANDLE SWD INTO THE TX TRANSPECOS REGION... THOUGH SRN EXTENT OF STORM DEVELOPMENT HAS BEEN LIMITED TO THE NERN TX PANHANDLE THUS FAR THIS AFTERNOON...MODELS SUGGEST THAT INCREASING LOW-LEVEL JET ACROSS W TX AND RETREATING DRYLINE OVERNIGHT MAY SUPPORT STORM DEVELOPMENT SWWD -- PERHAPS AS FAR SW AS THE TRANSPECOS REGION. ANY STORMS DEVELOPING IN THIS UNSTABLE/SUFFICIENTLY-SHEARED ENVIRONMENT WOULD BECOME SUPERCELLS...WITH THREAT FOR LARGE HAIL...LOCALLY-DAMAGING WINDS...AND A COUPLE OF TORNADOES. THUS WILL MAINTAIN CONDITIONAL SEVERE WEATHER PROBABILITIES ACROSS THIS REGION. ..GOSS.. 05/05/2007 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z