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| Probabilistic Tornado Graphic | |||||||||
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
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| Probabilistic Damaging Wind Graphic | |||||||||
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
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| Probabilistic Large Hail Graphic | |||||||||
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
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SPC AC 270555 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1255 AM CDT TUE AUG 27 2013 VALID 271200Z - 281200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER GREAT LAKES TO THE MID-UPPER OH VALLEY... ...GREAT LAKES TO THE MID-UPPER OH VALLEY REGION... A BAROCLINIC ZONE ORIENTED NW-SE FROM NRN-ERN WI...THROUGH SRN LOWER MI TO CENTRAL/ERN OH SHOULD REMAIN QUASI-STATIONARY THIS FORECAST PERIOD WITHIN THE NERN PERIPHERY OF A LARGE UPPER HIGH PRESSURE AREA CENTERED OVER ERN KS/MO. DESPITE RELATIVELY WEAK MIDLEVEL LAPSE RATES /AOB 6.5 C PER KM/...A MOIST AIR MASS /PW 1.5 TO 2 INCH/ INVOF THE SURFACE FRONT AND DIABATIC HEATING WILL RESULT IN MODERATE INSTABILITY /MLCAPE 1500-2500 J PER KG/ EXTENDING FROM THE UPPER MS VALLEY TO THE OH VALLEY AND CENTRAL APPALACHIANS. A CLUSTER OF TSTMS/MCS SHOULD BE ONGOING AT 12Z TODAY ACROSS PARTS OF ERN WI INTO CENTRAL AND SRN LOWER MI. AN APPARENT MCV AND/OR MIDLEVEL IMPULSE ASSOCIATED WITH THIS EARLY MORNING TSTM ACTIVITY IS EXPECTED TO TRACK SEWD INTO SRN LOWER MI AND THE MID-UPPER OH VALLEY FROM LATE THIS MORNING THROUGH THE AFTERNOON. FORECAST DESTABILIZATION DOWNSTREAM OF THIS MIDLEVEL SYSTEM SHOULD CONTRIBUTE TO NEW TSTM DEVELOPMENT AND/OR RE-INTENSIFICATION ALONG THE LEADING EDGE OF THE EARLY MORNING CLUSTER. STRENGTHENING EFFECTIVE BULK SHEAR PER 30-40 KT NWLY MIDLEVEL WINDS SPREADING ACROSS SRN LOWER MI INTO OH/WRN PA WILL SUPPORT STORM ORGANIZATION WITH THE POTENTIAL FOR MULTICELLS...A FEW SUPERCELLS...AND LINES/BOWS. HAIL AND DAMAGING WINDS WILL BE THE PRIMARY THREATS ACROSS THE SRN EXTENT OF THE SLIGHT RISK AREA. MEANWHILE...ACROSS THE NRN EXTENT OF THE SLIGHT RISK AREA...SURFACE HEATING INTO THE AFTERNOON IN THE WAKE OF ANY REMAINING CLOUDINESS OVER NRN-ERN WI THIS MORNING WILL SUPPORT DESTABILIZATION/MODERATE INSTABILITY. MODELS SUGGEST ANOTHER MIDLEVEL IMPULSE...EXPECTED TO BE TOPPING THE RIDGE OVER ND/NRN MN AT 12Z...WILL TURN SEWD TODAY REACHING NRN/ERN WI BY MID-LATE AFTERNOON. FORCING FOR ASCENT WITH THIS FEATURE AND LOW LEVEL WAA IN THE NOSE OF A RE-STRENGTHENING SWLY LLJ INTO WI SHOULD SUPPORT NEW TSTM DEVELOPMENT INVOF THE SURFACE FRONT IN NRN/ERN WI BY 21-00Z. EFFECTIVE BULK SHEAR OF 40-50 KT ORIENTED PARALLEL TO THE BAROCLINIC ZONE WILL SUPPORT SUPERCELLS WITH BOWING SEGMENTS POSSIBLE. DAMAGING WINDS AND HAIL WILL BE THE PRIMARY THREATS. WAA WITHIN THE NOSE OF A VEERING LLJ THIS EVENING/TONIGHT ACROSS SRN WI TO LOWER MI AND NRN IND/OH AND ASCENT WITH THE MIDLEVEL IMPULSE SHOULD FAVOR UPSCALE GROWTH INTO AN MCS ADVANCING SEWD...POTENTIALLY REACHING NRN/CENTRAL OH BY 12Z WEDNESDAY. DESPITE BOUNDARY LAYER STABILIZATION IN ADVANCE OF THIS MCS...A W/NWLY INFLOW OF MODERATE ELEVATED INSTABILITY AFTER 28/00Z SHOULD MAINTAIN THIS ACTIVITY SEWD WITH SOME REMAINING SEVERE WEATHER THREAT. ..PETERS/SMITH.. 08/27/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z |