The SPC is forecasting ...severe thunderstorms expected over parts of the central plains northeast into the upper mississippi valley this afternoon and tonight.... Please read the latest public statement about this event.
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SPC AC 252034 DAY 1 CONVECTIVE OUTLOOK CORR 1 NWS STORM PREDICTION CENTER NORMAN OK 0334 PM CDT SUN MAY 25 2008 VALID 252000Z - 261200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NRN WI..SE MN AND NW IA... ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF WCNTRL KS...SE NEB AND NW MO... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN PLAINS...CNTRL PLAINS...UPPER MIDWEST AND OZARK PLATEAU... CORRECTED GRAPHICS ...REGIONAL SEVERE WEATHER EVENT WITH TORNADOES POSSIBLE ACROSS NW WI...CNTRL WI...FAR SE MN AND NE IA... ...UPPER MIDWEST... AN UPPER-LEVEL TROUGH OVER THE NRN PLAINS WILL MOVE EWD INTO THE UPPER MS VALLEY THIS EVENING. AHEAD OF THE SYSTEM...A LOW-LEVEL JET WILL CONTINUE TO TRANSPORT MOISTURE NNEWD INTO THE REGION. OBJECTIVE ANALYSIS SHOWS MODERATE TO STRONG INSTABILITY HAS DEVELOPED ALONG AN AXIS FROM WRN IA EXTENDING INTO SE MN AND WRN WI WHERE SFC DEWPOINTS ARE RAPIDLY INCREASING. SFC DEWPOINTS ARE ALREADY NEAR 70 F IN NRN IA AND THIS AIRMASS SHOULD SPREAD QUICKLY NNEWD INTO SE MN AND WRN WI OVER THE NEXT FEW HOURS. INITIATION IS OCCURRING IN SCNTRL MN AND THE LATEST SHORT-TERM MODEL GUIDANCE SUGGESTS A BROKEN LINE OF STORMS WILL DEVELOP AND EXPAND SWWD FROM WRN WI AND ERN MN INTO NRN IA LATE THIS AFTERNOON. AT MID-LEVELS...RUC DATA SHOWS A 50 TO 70 KT JET MAX LOCATED FROM NEB NEWD ACROSS SRN MN. THIS FEATURE IS CREATING MODERATE TO STRONG VERTICAL SHEAR PROFILES WHICH WILL BE FAVORABLE FOR SUPERCELLS AS THE LINE ORGANIZES. CONCERNING THE LOW-LEVEL SHEAR ENVIRONMENT...REGIONAL WSR-88D VWPS SHOW 0-1 SRH VALUES IN THE 130 TO 200 M2/S2 RANGE SUGGESTING THE SHEAR ENVIRONMENT IS SUFFICIENT FOR TORNADOES. THE LOW-LEVEL SHEAR SHOULD INCREASE AS THE LOW-LEVEL JET EXPANDS NNEWD FROM WRN IA INTO WI LATE THIS AFTERNOON SUGGESTING A FEW STRONG TORNADOES WILL BE POSSIBLE WITH THE MORE PERSISTENT SUPERCELLS EMBEDDED IN THE LINE. OBJECTIVE ANALYSIS ALSO SHOWS A PLUME OF STEEP MID-LEVEL LAPSE RATES EXTENDING NNEWD ACROSS NRN MO...IA INTO WRN WI WITH 850 MB TO 500 MB LAPSE RATES AROUND 7.5 C/KM. THIS COMBINED WITH THE STRONG INSTABILITY WILL MAKE VERY LARGE HAIL A POSSIBILITY WITH THE MORE INTENSE STORMS. ...SRN AND CNTRL PLAINS... SOUTHWEST FLOW IS CURRENTLY IN PLACE ACROSS THE CNTRL AND SRN PLAINS ACCORDING TO WATER VAPOR IMAGERY AND A MID-LEVEL JET IS LOCATED ACROSS THE CNTRL ROCKIES. RUC ANALYSIS SHOWS THE 50 TO 70 KT MID-LEVEL JET ORIENTED SOUTHWEST TO NORTHEAST FROM CO TO NEB AND THIS FEATURE IS CREATING MODERATE VERTICAL SHEAR PROFILES ACROSS THE NWRN PART OF THE REGION. AT THE SFC...DEWPOINTS ARE IN THE LOWER TO MID 60S F IN NW KS AND IN THE TX PANHANDLE. THIS IS CONTRIBUTING TO MODERATE INSTABILITY LOCATED JUST SOUTHEAST OF THE BOUNDARY WITH MLCAPE VALUES RANGING FROM 1500 TO 3000 J/KG. THUNDERSTORMS ARE DEVELOPING ALONG AND JUST SOUTHEAST OF THE BOUNDARY AND SSWWD ALONG A DRYLINE INTO THE WRN TX PANHANDLE. THIS ACTIVITY SHOULD EXPAND IN COVERAGE WITH THE DEVELOPMENT OF AN MCS LIKELY LATE THIS AFTERNOON. MODEL FORECASTS AGREE WITH A LARGE CLUSTER OF THUNDERSTORMS MOVING NEWD INTO NRN KS AND INTO THE MID-MO VALLEY BY LATE THIS EVENING. CONCERNING THE SEVERE POTENTIAL...OBJECTIVE ANALYSIS SHOWS MODERATE VERTICAL SHEAR INCREASES MARKEDLY FROM SOUTHEAST TO NORTHWEST ACROSS THE CNTRL PLAINS. THE LATEST WSR-88D VWPS FROM WRN KS SHOW ABOUT 30 KT OF VERTICAL SHEAR AND SHEAR IS LIKELY GREATER IN NW KS CLOSER TO THE MID-LEVEL JET. IN ADDITION...VWPS SHOW ENOUGH SPEED SHEAR IN THE BOUNDARY LAYER FOR A TORNADO THREAT WITH SUPERCELLS. TORNADOES MAY ALSO DEVELOP ALONG OUTFLOW BOUNDARIES ASSOCIATED WITH ORGANIZED MULTICELLS. LARGE HAIL WILL ALSO BE LIKELY WITH THE MORE INTENSE STORMS DUE TO A PLUME OF STEEP LAPSE RATES EXTENDING NNEWD FROM THE WRN TX PANHANDLE ACROSS NW KS. VERY LARGE HAIL MAY OCCUR WITH THE MORE PERSISTENT SUPERCELLS. AS THE MCS ORGANIZES AND MOVES INTO NRN KS AND SE NEB LATER THIS EVENING...THE WIND DAMAGE POTENTIAL MAY ALSO BECOME ENHANCED. ..BROYLES.. 05/25/2008 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z