MESOSCALE DISCUSSION 0134
   NWS STORM PREDICTION CENTER NORMAN OK
   0941 PM CST THU FEB 24 2011
   
   AREAS AFFECTED...E-CNTRL IL...NRN IND...NRN OH...EXTREME SERN LOWER
   MI
   
   CONCERNING...HEAVY SNOW 
   
   VALID 250341Z - 250945Z
   
   SNOW WILL OVERSPREAD PORTIONS OF E-CNTRL IL...NRN IND...NRN OH...AND
   EXTREME SERN LOWER MI OVERNIGHT TONIGHT. RATES OF 1 TO 2 INCHES ARE
   EXPECTED...ESPECIALLY ACROSS PORTIONS OF NRN IND/OH.
   
   INTENSE 850-700-MB FRONTOGENESIS IS FORECAST TO OVERSPREAD THE
   DISCUSSION AREA DURING THE OVERNIGHT HOURS...AS THE DEFORMATION ZONE
   ASSOCIATED WITH THE EXTRATROPICAL CYCLONE OVER THE MISSISSIPPI
   VALLEY REGION SHIFTS E-NEWD. THIS WILL SUPPORT SNOWFALL RATES OF 1
   TO 2 INCHES PER HOUR...AS RUC FORECAST SOUNDINGS INDICATE
   TEMPERATURES THROUGHOUT THE DEPTH OF THE TROPOSPHERE FALLING TO OR
   BELOW FREEZING TONIGHT ACROSS MOST OF THE REGION. THESE SOUNDINGS
   ALSO INDICATE NEARLY ISOTHERMAL LAYERS BETWEEN 850 AND 700 MB /WITH
   TEMPERATURES AOB FREEZING/ ACROSS PORTIONS OF NRN IND/OH AFTER
   04Z...INDICATING THE POTENTIAL FOR EFFICIENT SNOW AGGREGATION. THE
   HIGHEST SNOWFALL TOTALS ARE EXPECTED TO OCCUR IN THIS REGION...WHERE
   GREATER AMOUNTS OF DEEP-LAYER MOISTURE IN ASSOCIATION WITH THE WARM
   CONVEYOR BELT LEADING THE CYCLONE ARE PRESENT. THE 00Z RUN OF THE
   NAM INDICATES AMPLE SLANTWISE INSTABILITY SPREADING ACROSS THE AREA
   TONIGHT...ENHANCING THE POTENTIAL FOR BANDED PRECIPITATION AND
   HIGHER SNOWFALL TOTALS. HEAVY SNOW WILL PERSIST THROUGH THE
   OVERNIGHT HOURS. ALSO OF NOTE...A NARROW CORRIDOR OF FREEZING
   RAIN/SLEET MAY OCCUR ACROSS EXTREME SRN PORTIONS OF THE DISCUSSION
   AREA...WHERE LOWER TROPOSPHERIC TEMPERATURES ARE SLIGHTLY WARMER.
   THE 00Z RUN OF THE EXPERIMENTAL HRRR INDICATES THE SNOW TAPERING OFF
   ACROSS IL/IND AFTER 10Z WHILE PERSISTING ACROSS NRN OH INTO FRIDAY
   MORNING.
   
   ..COHEN.. 02/25/2011
   
   
   ATTN...WFO...CLE...ILN...DTX...IWX...IND...LOT...ILX...
   
   LAT...LON   40328310 39928604 39798745 39988852 40808838 41318723
               41878464 42038285 41638073 40978085 40328310