MESOSCALE DISCUSSION 2366
   NWS STORM PREDICTION CENTER NORMAN OK
   0212 PM CST TUE NOV 29 2011
   
   AREAS AFFECTED...PORTIONS OF SRN/ERN LOWER MI...FAR NRN IND...FAR
   NWRN OH
   
   CONCERNING...HEAVY SNOW 
   
   VALID 292012Z - 300015Z
   
   SNOWFALL RATES OF 1 TO LOCALLY 1.5 IN/HR WILL SPREAD ACROSS PORTIONS
   OF SRN/ERN LOWER MI...FAR NRN IND...AND FAR NWRN OH THROUGH THE
   EVENING...WITH THE SNOW CONTINUING INTO THE OVERNIGHT HOURS.
   
   WATER VAPOR IMAGERY DEPICTS THE WRN SEGMENT OF A BIFURCATED WARM
   CONVEYOR BELT PEELING AROUND A DEEP-LAYER CYCLONE FROM SRN ONTARIO
   INTO LOWER MI AND FARTHER S INTO IND/IL. MODIFIED MARITIME PARCEL
   TRAJECTORIES EMBEDDED WITHIN THIS BELT ARE SUPPORTING A BROAD ZONE
   OF 0.85-1-INCH PW VALUES PER GPS DATA. AND...WITH VERTICALLY VEERING
   WIND PROFILES AND INFERRED WAA PER VWP DATA...A BROAD SHIELD OF
   DEFORMATION ZONE PRECIP WILL BE MAINTAINED OVER THE NWRN SEMICIRCLE
   OF THE NEWD-MIGRATING CYCLONE INTO THE EVENING HOURS. DESPITE
   WEAKENING 850-500-MB FRONTOGENESIS...WEAK ELEVATED INSTABILITY
   COMBINED WITH ADEQUATE MOISTURE WILL LIKELY MAINTAIN THE PRECIP
   SHIELD INTO THE EVENING AND OVERNIGHT HOURS /TAPERING OFF AFTER
   06Z/. TURRET STRUCTURES AMIDST THE LOW/MID-LEVEL CLOUD DECK PER
   RECENT VISIBLE SATELLITE IMAGES ARE MANIFESTATIONS OF THE VERY
   MODEST INSTABILITY /MUCAPE VALUES BELOW 100 J PER KG/ ROOTED ABOVE
   THE 600-MB LEVEL...AND AN ISOLATED LIGHTNING STRIKE OR TWO CANNOT BE
   RULED OUT WITH THE MOST INTENSE PRECIP BANDS.
   
   WHILE RAIN IS CURRENTLY THE PRIMARY PRECIP TYPE ACROSS THE
   DISCUSSION AREA...SFC MESOANALYSIS DEPICTS A COLD POCKET /TEMPS IN
   THE LOWER TO MIDDLE 30S/ EVOLVING OVER CNTRL IND WHERE LIGHT TO
   MODERATE SNOW IS BEING REPORTED. THIS IS THE RESULT OF COLUMNAR
   ADIABATIC COOLING OWING TO STRONGLY FORCED ASCENT. AS THIS ASCENT
   OVERSPREADS THE DISCUSSION AREA FROM THE SSW...AND NOCTURNAL COOLING
   EVENTUALLY COMMENCES...THERMAL PROFILES WILL BE SUFFICIENTLY COLD
   FOR PREDOMINANTLY SNOW AFTER 23Z. SNOWFALL RATES OF 1 TO LOCALLY 1.5
   IN/HR ARE ANTICIPATED...GREATEST OVER S-CNTRL LOWER MI...FAR NRN
   IND...AND EXTREME NWRN OH PRIOR TO 01Z. HEAVY SNOW WILL LIKELY
   REMAIN W/NW OF METRO DETROIT. ALSO OF NOTE...THE TIGHT SFC PRESSURE
   GRADIENT WILL SUPPORT NLY WINDS OF 15-20 MPH WITH GUSTS REACHING
   30-35 MPH...POTENTIALLY SUPPORTING BLOWING SNOW. HOWEVER...THE WET
   NATURE OF THE SNOW WILL INITIALLY MITIGATE THIS THREAT THROUGH
   MID-EVENING BEFORE ACCUMULATIONS ARE UNDERWAY.
   
   ..COHEN.. 11/29/2011
   
   
   ATTN...WFO...DTX...APX...IWX...GRR...
   
   LAT...LON   43248249 42718292 42318351 41678430 41388489 41368598
               41808646 42628574 43698448 44088358 44028271 43248249