MESOSCALE DISCUSSION 2236
   NWS STORM PREDICTION CENTER NORMAN OK
   0628 AM CST SUN DEC 16 2007
   
   AREAS AFFECTED...NORTHEAST INDIANA/NORTHWEST OH/LOWER MI
   
   CONCERNING...HEAVY SNOW 
   
   VALID 161228Z - 161630Z
   
   MODERATE TO LOCALLY HEAVY SNOW WITH 1 IN/HR RATES WILL CONTINUE OVER
   THE NEXT SEVERAL HOURS ACROSS FAR NORTHEAST INDIANA/NORTHWEST OH
   INTO SOUTHEAST LOWER MI...WITH THE HEAVIER SNOW EXPECTED TO
   GRADUALLY TAPER FROM SOUTHWEST TO NORTHEAST THROUGH 15Z-18Z. GIVEN
   INCREASINGLY STRONG NORTHERLY WINDS...BLIZZARD-LIKE CONDITIONS WILL
   BE POSSIBLE THIS MORNING...WITH BLOWING AND DRIFTING SNOW.
   
   LATEST DIAGNOSTIC/UPPER AIR DATA FEATURES PROGRESSIVELY CLOSED MID
   LEVEL CYCLONE CROSSING THE OHIO VALLEY...WITH 12Z SURFACE ANALYSIS
   DEPICTING A CONTINUALLY DEEPENING SURFACE LOW /991 MB/ CENTERED NEAR
   CLEVELAND. IN THE NORTHWEST QUADRANT OF THIS CYCLONE...A
   TIGHTENING/ENE SHIFTING DEFORMATION ZONE HAS BEEN RESPONSIBLE FOR
   WIDESPREAD MODERATE TO HEAVY SNOW EARLY THIS MORNING...WITH
   MESOSCALE BANDING/ENHANCEMENT COMMON OWING TO SLANTWISE INSTABILITY
   COINCIDENT WITH LOW TO MID LEVEL FRONTOGENETICAL FORCING. THIS
   INCLUDES THUNDERSNOW ACROSS SOUTHEAST LOWER MI. 
   
   HOWEVER...SIMILAR TO OBSERVATIONAL TRENDS...SHORT TERM 09Z RUC/06Z
   NAM GUIDANCE SUGGEST A DIMINISHING/WEAKENING TREND OF OVERALL LARGE
   SCALE/MESOSCALE INGREDIENTS AND WANING POTENTIAL FOR INSTABILITY
   RELEASE...WHICH SHOULD LEAD TO GRADUALLY DECREASING SNOW RATES
   THROUGH 15Z-18Z. POTENTIAL FOR MODERATE TO LOCALLY HEAVY SNOW WILL
   LINGER LONGEST ACROSS SOUTHEAST LOWER MI/NORTHWEST OH. STRONG
   NORTHERLY WINDS OFF LAKE HURON MAY PROVIDE SOME ADDITIONAL LAKE
   ENHANCEMENT ACROSS THE SOUTHEAST LOWER MI THUMB REGION THIS MORNING.
   OTHERWISE...SIMILAR TO TRENDS OBSERVED WITH THE WOLCOTT INDIANA
   PROFILER...09Z RUC GUIDANCE SUGGESTS NORTHERLY WINDS AROUND 1 KM/850
   MB SHOULD INCREASE TO AROUND 50 KT THROUGH 15Z-18Z...WHICH WILL
   PROVIDE BLIZZARD-LIKE CONDITIONS EVEN AS SNOW RATES BEGIN TO
   DIMINISH.
   
   ..GUYER.. 12/16/2007
   
   
   ...NOTICE...
   SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
   SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
   TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
   FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.
   
   ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND...
   
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