MESOSCALE DISCUSSION 0040
   NWS STORM PREDICTION CENTER NORMAN OK
   0400 PM CST WED JAN 14 2009
   
   AREAS AFFECTED...NWRN IN...EXTREME NERN IL AND SWRN MI
   
   CONCERNING...HEAVY SNOW 
   
   VALID 142200Z - 150400Z
   
   A BAND OF LAKE EFFECT SNOW IS EXPECTED TO DEVELOP OVER SOUTHERN LAKE
   MICHIGAN WITH RATES UP TO 2 IN/HR...AFFECTING MAINLY NORTHWESTERN
   IND BY 00Z/15.
   
   22Z SURFACE OBSERVATIONS AND REGIONAL RADAR REFLECTIVITY SHOW A
   NARROW BAND OF SNOWFALL ALIGNED ALONG THE N-S AXIS OF LAKE
   MICHIGAN...OCCURRING WITHIN A ZONE OF STRONG LOW LVL CONVERGENCE. WV
   IMAGERY AND SHORT TERM MODEL GUIDANCE INDICATE A MID LVL S/W TROUGH
   WILL MOVE SOUTH ACROSS THE REGION BY 00Z/15. THIS WILL CAUSE
   BOUNDARY LAYER MEAN FLOW /AND AXIS OF LOW LVL CONVERGENCE/ TO BECOME
   REORIENTED FROM A NNE-SSW POSITION TO NNW-SSE BY 00Z/15...RESULTING
   IN LE SNOW BAND SHIFTING FROM COOK COUNTY IL INTO MAINLY PORT AND LA
   PORTE COUNTIES IN IND. ADDITIONAL INFLUX OF COLD AIR WILL MOVE SOUTH
   WITH THE MID LVL TROUGH...AIDING IN STEEPENING LOW LVL LAPSE RATES
   AND INCREASING BOUNDARY LAYER DEPTH THROUGH 3 KM AGL.
   THEREFORE...CONVECTIVELY ENHANCED LE SNOWBAND WILL BE FAVORED OVER
   NORTHWESTERN IND...WITH SNOWFALL RATES UP TO 2 IN/HR BY LATE
   AFTERNOON THROUGH THE EARLY EVENING.
   
   ..GARNER/SMITH.. 01/14/2009
   
   
   ...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...IWX...LOT...
   
   LAT...LON   41308628 41078719 41278763 41758755 42188637 41778594
               41488601 41308628