The SPC is forecasting ...severe thunderstorms expected over parts of the lower ohio and tennessee valleys to southern lake michigan this afternoon and tonight.... Please read the latest public statement about this event.
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SPC AC 180609 DAY 1 CONVECTIVE OUTLOOK RESENT 1 NWS STORM PREDICTION CENTER NORMAN OK 0109 AM CDT THU OCT 18 2007 VALID 181200Z - 191200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF THE OH VALLEY AND GREAT LAKES... ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE LOWER MS VALLEY THROUGH TN AND OH VALLEYS AND GREAT LAKES... ...SYNOPSIS... LEAD SHORTWAVE TROUGH NOW MOVING INTO THE MID MS VALLEY REGION WILL LIFT NEWD INTO THE GREAT LAKES EARLY THURSDAY. ATTENDANT SURFACE LOW WILL SHIFT NWD AND CONSOLIDATE OVER THE UPPER MS VALLEY WHILE WARM FRONT LIFTS NWD THROUGH THE GREAT LAKES. UPSTREAM IMPULSE NOW DROPPING INTO THE CNTRL ROCKIES WILL ADVANCE INTO THE MID MS VALLEY THURSDAY AFTERNOON AND EVENING...REACHING THE TN AND OH VALLEYS THURSDAY NIGHT ACCOMPANIED BY A COLD FRONT. ...TN VALLEY THROUGH OH VALLEY AND GREAT LAKES REGIONS... RICHER BOUNDARY LAYER MOISTURE NOW RESIDING OVER THE LOWER MS VALLEY WILL ADVECT NWD THROUGH THE BROAD WARM SECTOR ALONG STRONG LOW LEVEL JET INTO THE TN AND OH VALLEYS WITH MID TO UPPER 60S DEWPOINTS LIKELY. WIDESPREAD CLOUDS AND THUNDERSTORMS WILL LIKELY BE ONGOING WITHIN ZONE OF ASCENT ASSOCIATED WITH EJECTING LEAD WAVE FROM THE GREAT LAKES THROUGH PARTS OF THE OH AND TN VALLEYS. IN WAKE OF LEAD WAVE...MID LEVEL DRY SLOT WILL LIKELY SHIFT NEWD DURING THE AFTERNOON OVER A PORTION OF THE WARM SECTOR. THIS ALONG WITH STRONG BOUNDARY LAYER FLOW WILL PROMOTE LOW CLOUDS MIXING OUT FROM THE SW DURING THE AFTERNOON. THESE PROCESSES SHOULD RESULT IN AN AXIS MODERATE INSTABILITY FROM PARTS OF THE GREAT LAKES INTO THE OH...WRN TN AND LOWER MS VALLEYS WITH MLCAPE FROM 1000 TO 2000 J/KG. STORMS SHOULD REDEVELOP BY LATE AFTERNOON FROM PARTS OF THE LOWER MS VALLEY NWD INTO THE OH VALLEY AND GREAT LAKES AHEAD OF COLD FRONT AS THE ATMOSPHERE DESTABILIZES AND FORCING FOR ASCENT INCREASES WITH APPROACHING SHORTWAVE TROUGH. SOME WEAKENING AND VEERING OF THE LOW LEVEL FLOW MAY OCCUR IN WAKE OF LEAD WAVE EARLY THURSDAY. HOWEVER...KINEMATIC PROFILES SHOULD STRENGTHEN AGAIN THURSDAY AFTERNOON IN ADVANCE OF APPROACHING SHORTWAVE TROUGH. STRONG DEEP SHEAR AND LARGE LOW LEVEL HODOGRAPHS WILL PROMOTE A THREAT FOR SUPERCELLS CAPABLE OF PRODUCING A FEW TORNADOES...A COUPLE OF WHICH COULD BE STRONG. STORMS MAY EVENTUALLY EVOLVE INTO LINES OR A MIX OF LINE SEGMENTS AND CELLS AS THEY ADVANCE EWD THROUGH THE EVENING WITH A CONTINUED THREAT FOR MAINLY DAMAGING WIND AND ISOLATED TORNADOES. ...ERN NEB...NERN KS AND NWRN MO... STEEP MID LEVEL LAPSE RATES ASSOCIATED WITH COLD AIR ALOFT AND ASCENT ATTENDING VORT MAX ROTATING SEWD THROUGH UPPER TROUGH WILL LIKELY PROMOTE THE DEVELOPMENT OF STORMS OVER ERN PARTS OF THE CNTRL PLAINS. ACTIVITY MAY INTENSIFY AS THE BOUNDARY LAYER DESTABILIZES WITH A THREAT FOR MAINLY HAIL AND STRONG WIND GUSTS. AT THIS TIME IT APPEARS INSTABILITY MAY BE TOO MARGINAL FOR A CATEGORICAL RISK AREA. ..DIAL/GUYER.. 10/18/2007 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z