The SPC is forecasting ...significant severe thunderstorms expected over the upper mississippi valley into parts of the mid missouri valley today and tonight.... Please read the latest public statement about this event.
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SPC AC 171626 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1126 AM CDT THU JUN 17 2010 VALID 171630Z - 181200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER PORTIONS OF EASTERN SD...EASTERN NEB...CENTRAL/SOUTHERN MN...MUCH OF IA...AND WESTERN WI... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE MIDWEST STATES... ...THERE IS A SLGT RISK OF SVR TSTMS FROM SOUTHEAST MO/SOUTHERN IL INTO MS/AL... ...UPPER MIDWEST... A POWERFUL SHORTWAVE TROUGH IS ROTATING OUT OF THE NORTHERN HIGH PLAINS AND INTO THE DAKOTAS TODAY...WITH AN ASSOCIATED 60-70 KNOT MID LEVEL JET MAX NOSING INTO MN. LATEST SURFACE ANALYSIS SHOWS A COLD FRONT SURGING EASTWARD ACROSS SD/NEB...WHICH IS LIKELY TO BE THE PRIMARY FOCUS FOR INTENSE THUNDERSTORM ACTIVITY LATER TODAY. STRONG SOUTHERLY LOW LEVEL WINDS AHEAD OF THE FRONT WILL MAINTAIN NEAR 70F DEWPOINTS ACROSS EASTERN SD/NEB AND PORTIONS OF MN/IA WHERE AFTERNOON MLCAPE VALUES OF 3000+ J/KG ARE EXPECTED. INCREASING WINDS ALOFT WILL RESULT IN A VERY FAVORABLE ENVIRONMENT FOR SEVERE STORMS BY MID-LATE AFTERNOON. INITIAL THUNDERSTORM DEVELOPMENT IS EXPECTED BY EARLY AFTERNOON ALONG THE FRONT OVER EASTERN SD AND NORTHEAST NEB. FORECAST SOUNDINGS IN THIS REGION SHOW SUBSTANTIAL LOW LEVEL AND DEEP LAYER VERTICAL SHEAR...WITH SHEAR VECTORS PERPENDICULAR TO THE FRONT SUGGESTING DISCRETE SUPERCELLS ARE LIKELY. SUFFICIENTLY LOW LCL HEIGHTS FURTHER INDICATE THAT A FEW TORNADOES /POSSIBLY STRONG/ MAY OCCUR DURING THE FIRST FEW HOURS OF THE EVENT. VERY LARGE HAIL IS ALSO A POSSIBILITY WITH SUPERCELL STRUCTURES ACROSS CENTRAL/ SOUTHERN MN AND WESTERN/CENTRAL IA THROUGH EARLY EVENING. WITH TIME...LINEAR FORCING MECHANISMS WILL PROMOTE A MORE ORGANIZED SQUALL LINE WITH WIDESPREAD DAMAGING WINDS BEING THE MOST LIKELY THREAT ACROSS EASTERN MN INTO WESTERN WI. ...MID MS AND TN VALLEYS... A COUPLE OF REMNANT MCSS ARE TRACKING SOUTHEASTWARD ALONG LOW LEVEL INSTABILITY GRADIENT FROM SOUTHERN IL INTO MIDDLE TN. A VERY MOIST AND UNSTABLE AIR MASS NEAR AND SOUTHWEST OF THIS AREA WILL HELP STORMS INTENSIFY THROUGH THE AFTERNOON...DESPITE RATHER WEAK WIND FIELDS. LOCALLY DAMAGING WINDS AND HAIL WILL BE POSSIBLE WITH THESE STORMS. ...TX PANHANDLE... MOST MODEL GUIDANCE INDICATES A CLUSTER OF THUNDERSTORMS WILL DEVELOP OVER EASTERN NM/WEST TX LATER THIS AFTERNOON AND SPREAD INTO THE WESTERN TX PANHANDLE. GIVEN THE HOT/MOIST ENVIRONMENT... STRONGER STORMS MAY PRODUCE DAMAGING WINDS. AREAL COVERAGE AND DURATION OF THREAT IS UNCERTAIN...SO WILL MAINTAIN ONLY LOW SEVERE PROBABILITIES AT THIS TIME. ..HART/GRAMS.. 06/17/2010 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z