The SPC is forecasting ...severe thunderstorms expected over parts of the mid mississippi valley...the ohio valley...and the central appalachians through tonight.... Please read the latest public statement about this event.
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SPC AC 191629 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1129 AM CDT FRI JUN 19 2009 VALID 191630Z - 201200Z ...THERE IS A MDT RISK OF SVR TSTMS SERN IA...NERN MO...CENTRAL/NRN IL AND IN..OH...NRN KY... SWRN PA AND WRN WV... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK AREA...FROM THE SRN/CENTRAL PLAINS EWD TO THE MID ATLANTIC COAST... ...SYNOPSIS... UPPER RIDGE REMAINS ANCHORED OVER THE GULF COASTAL STATES...WITH A BROAD TROUGH IN THE WEST. THIS IS RESULTING IN MODERATELY STRONG MID/HIGH FLOW ARCING FROM THE SRN/CENTRAL PLAINS NEWD INTO THE GREAT LAKES AND SEWD INTO THE CAROLINAS. MAIN UPPER FEATURE FOR CONVECTIVE DEVELOPMENT LATER TODAY WILL BE A STRONGER IMPULSE MOVING FROM CO ENEWD INTO IA BY EVENING...AND THEN EWD INTO THE OH VALLEY OVERNIGHT. AT THE SURFACE...A COLD FRONT IS FORECAST TO STRETCH FROM WRN UPPER MI SWWD INTO ERN/SRN KS BY LATE AFTERNOON. ...SRN MO RIVER VALLEY/GREAT LAKES AND OH VALLEY... SEVERE MCS IN EXTREME SRN WI/NRN IL AT MID MORNING IS LIKELY TO SHIFT E/ESEWD ALONG OUTFLOW BOUNDARY/INSTABILITY AXIS STRETCHING FROM NRN IL ESEWD INTO CENTRAL OH. DEEP LAYER SHEAR AT 50-60 KT AND STRONG INSTABILITY IS LIKELY TO MAINTAIN A SEVERE THREAT THROUGH THE DAY WITH THIS SYSTEM. THE STRONGER FLOW ALOFT AND INSTABILITY MAY SUSTAIN A SEVERE THREAT WITH THIS COMPLEX AS FAR EAST AS SWRN PA/WV. SOUTH OF THIS COMPLEX...RICH LOW LEVEL MOISTURE/LOWER TO MID 70 DEWPOINTS/ WILL REMAIN SITUATED ACROSS THE MID MS AND OH VALLEYS. HEATING OF THIS VERY MOIST BOUNDARY LAYER...COMBINED WITH AN ELEVATED MIXED LAYER...WILL YIELD STRONG INSTABILITY...MLCAPES FROM 2500-3500 J/KG THIS AFTERNOON. STORMS ARE LIKELY TO INITIATE AS CONVERGENCE INCREASES ALONG/AHEAD OF APPROACHING COLD FRONT/UPPER SHORTWAVE TROUGH. WIND FIELDS AND THERMODYNAMIC PROFILES APPEAR FAVORABLE FOR BOTH SUPERCELLS AND LINES/BOWING SEGMENTS. WHILE HAIL...AND SOME TORNADOES ARE EXPECTED WITH THE MORE DISCRETE STORMS...THE WIND THREAT SHOULD INCREASE AS THE STORMS GRADUALLY EVOLVE INTO ONE OR TWO SEVERE FORWARD-PROPAGATING MCS/S BY LATE IN THE DAY. THE DEGREE OF INSTABILITY/SHEAR ALSO FAVORS WIDESPREAD AND SIGNIFICANT DAMAGING WINDS AS THE MCS/S MOVE RAPIDLY EWD. CLUSTERS ARE EXPECTED TO TRACK SOUTH OF CURRENT MCS/BOUNDARIES...OR ROUGHLY FROM SRN/CENTRAL IL EWD INTO NRN KY/SRN OH AND WV. ...WV/NC... LEADING MCS MOVING THROUGH WV THIS MORNING HAD WEAKENED AS IT ENCOUNTERED THE HIGHER TERRAIN. THERE IS A POSSIBILITY THESE STORMS WILL REINTENSIFY AS THEY SHIFT SEWD INTO SRN VA/NC THIS AFTERNOON. NEGATIVES FOR REINTENSIFICATION ARE RELATIVELY WARM 500 MB TEMPERATURES AND SLIGHT HEIGHT RISES. FACTORS FAVORING STORMS BECOMING SEVERE ARE STORMS MOVING SEWD ALONG INSTABILITY AXIS AND WLY LOW LEVEL JET SUPPLYING GREATER INSTABILITY. ...SERN MN/WI/UPPER MI... THOUGH CLOUDS HAVE LIMITED LOW LEVEL DESTABILIZATION/HEATING THUS FAR...SUFFICIENT LARGE SCALE LIFTING AHEAD OF CENTRAL PLAINS TROUGH WILL SUPPORT SCATTERED STORMS THROUGH THE AFTERNOON HOURS. DESPITE WEAK HEATING...STEEP MID LEVEL LAPSE RATES AND COOLING TEMPERATURES ALOFT MAY YIELD SEVERE HAIL/LOCALLY DAMAGING WINDS. ...SRN PLAINS... WITHIN MOIST TROPICAL PLUME...AN MCV WAS EVIDENT IN RADAR/SATELLITE IMAGERY NEAR SJT AT 15Z...MOVING NWD AT 25-30 KT. LIFT ASSOCIATED WITH THIS SYSTEM AND DIFFERENTIAL HEATING ON ERN SIDE OF THICKER CLOUDS ARE EXPECTED TO AID IN CONVECTION DEVELOPING THIS AFTERNOON/EVENING. LOW LEVEL LAPSE RATES WILL STEEPEN AS TEMPERATURES WARM INTO THE 90S...AND ENHANCE THE POTENTIAL FOR STRONG/SEVERE GUSTY WINDS. SINCE STORMS ARE EXPECTED TO BE ORGANIZED...GIVEN 25-35 KT DEEP LAYER SHEAR AND SBCAPES AROUND 2500 J/KG...A SLIGHT RISK HAS BEEN ADDED FOR A WIND THREAT ACROSS PORTIONS OF OK AND NWRN TX THIS AFTERNOON. ...GREAT BASIN... AS AN UPPER WAVE MOVES INTO THE PACIFIC NW...A COLD FRONT WILL SHIFT EWD INTO THE GREAT BASIN AND PROVIDE FOCUS FOR A FEW HIGH BASED DIURNALLY DRIVEN STORMS. INVERTED-V THERMODYNAMIC ENVIRONMENT WILL PROMOTE A THREAT OF A FEW STRONG/SEVERE GUSTS INTO THE EARLY EVENING HOURS. ..IMY/GARNER.. 06/19/2009 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z