The SPC is forecasting an outbreak of severe thunderstorms today and tonight across portions of the United States. This is an extremely dangerous situation. Please read the latest public statement about this event.
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SPC AC 051239 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0739 AM CDT MON JUN 05 2006 VALID 051300Z - 061200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF KS AND NEB... ...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN PARTS OF THE SRN PLNS TO THE UPR MS VLY... ...SYNOPSIS... LITTLE CHANGE EXPECTED IN THE LARGE SCALE PATTERN OVER THE LWR 48. DOMINANT SWRN U.S. RIDGE SHOULD REBOUND SOMEWHAT IN WAKE OF POTENT SHORTWAVE IMPULSE NOW OVER SASKATCHEWAN/ERN MT. THE SHORTWAVE SHOULD CONTINUE E INTO MN BY THE END OF THE PERIOD AS UPSTREAM JET STREAK NOW OFF THE N PACIFIC CST REACHES MT. IN THE EAST... ANOMALOUSLY DEEP TROUGH/LOW EXPECTED TO FURTHER AMPLIFY AS IT EDGES SLOWLY E TOWARD THE CST. AT LWR LEVELS...FRONTAL SYSTEM ACCOMPANYING MT TROUGH WILL BE COMPLICATED BY CONVECTIVE OUTFLOW FROM ONGOING STORMS...AND BY DIFFUSE NNW/SSE-ORIENTED STATIONARY FRONT OVER ERN PARTS OF THE CNTRL/SRN PLNS. ...CNTRL/SRN PLNS... SATELLITE AND...TO SOME EXTENT...THE MODELS CONTINUE TO SUGGEST THAT PART OF THE SASKATCHEWAN/MT DISTURBANCE WILL DROP SE ACROSS THE CNTRL PLNS LATER TODAY/TONIGHT...ENHANCING DEEP NWLY FLOW AND ASCENT ON ERN FLANK OF SWRN U.S. RIDGE. OVERNIGHT MCS IN NEB HAS COMPLICATED SURFACE PATTERN/WARM SECTOR AHEAD OF MAIN COLD FRONT ASSOCIATED WITH THE MT TROUGH. OUTFLOW FROM THIS COMPLEX LIKELY WILL CONFINE GREATEST SURFACE-BASED INSTABILITY TO AREAS W AND S OF EXPECTED MIDDAY POSITION OF THE WEAKENING SYSTEM OVER SE NEB/NE KS. STRONG SURFACE HEATING S/W OF CONVECTIVE OUTFLOW...AND APPROACH OF SYNOPTIC COLD FRONT...EXPECTED TO OVERCOME CAP AND SUPPORT RENEWED STORM DEVELOPMENT OVER CNTRL NEB/SW NEB AND NRN/NWRN KS LATE THIS AFTERNOON. GIVEN EXPECTED DEGREE OF INSTABILITY /SBCAPE TO 3000 J PER KG/...STEEP LOW TO MID LEVEL LAPSE RATES...30+ KT WNWLY MID LEVEL FLOW ON SRN FRINGE OF UPR TROUGH...AND PERSISTENT SSELY LOW LEVEL FLOW INVOF AFOREMENTIONED STATIONARY FRONT...SETUP SHOULD SUPPORT INTENSE UPDRAFTS/SUSTAINED STORMS WITH LARGE HAIL AND HIGH WIND. FOCUSED AREA FOR ASCENT AND THERMODYNAMIC CONSIDERATIONS SUGGEST THAT ACTIVITY WILL ORGANIZE INTO ONE OR TWO LARGE FORWARD-PROPAGATING CLUSTERS. SETUP SHOULD FAVOR A GENERAL E/SE MOTION OF THE SYSTEMS...WITH A THREAT FOR HIGH WIND AND HAIL CONTINUING ACROSS A LARGE PART OF CNTRL/ERN KS AND PERHAPS THE NW HALF OF MO TONIGHT. DURING THE EARLY STAGES OF STORM DEVELOPMENT...A LIMITED THREAT WILL EXIST FOR A TORNADO OR TWO IN NRN KS/CNTRL NEB. ...ERN DAKOTAS/MN... COLD FRONT ASSOCIATED WITH MT TROUGH SHOULD SERVE AS A FOCUS FOR DIURNALLY-ENHANCED STORMS OVER THE ERN DAKOTAS AND MN LATER TODAY...WITH THE BOUNDARY EXPECTED TO EXTEND FROM NW MN ACROSS ERN SD INTO CNTRL NEB/NE CO BY 00Z THIS EVENING. WHILE INSTABILITY WILL BE MORE LIMITED RELATIVE TO POINTS SOUTH...SUFFICIENT SBCAPE /1500 J PER KG/ SHOULD BE PRESENT TO SUPPORT SUSTAINED STORMS/POSSIBLE SUPERCELLS WITH HAIL/HIGH WIND AND PERHAPS ONE OR TWO TORNADOES. THE THREAT SHOULD DIMINISH LATER THIS EVENING AS CORRIDOR OF ASCENT MOVES BEYOND LOW LEVEL INSTABILITY AXIS IN MN. ...SERN U.S... SCTD TSTMS ARE EXPECTED TO DEVELOP ALONG SEA BREEZE FRONT ERN FL NWD INTO THE ERN CAROLINAS. STEEP LAPSE RATES ALOFT ASSOCIATED WITH SLOWLY-MOVING UPR TROUGH AND STRONG HEATING SUGGEST THAT A FEW MAY YIELD ISOLD HAIL AND/OR DAMAGING WIND. ..CORFIDI/TAYLOR.. 06/05/2006 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z