Aug 27, 2013 0600 UTC Day 1 Convective Outlook

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.

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