MESOSCALE DISCUSSION 0252
   NWS STORM PREDICTION CENTER NORMAN OK
   0857 PM CDT TUE MAR 22 2011
   
   AREAS AFFECTED...NRN AND CNTRL LOWER MI
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 230157Z - 230700Z
   
   SNOW BAND ACROSS CNTRL AND NRN LOWER MI IS BECOMING BETTER DEFINED
   AND MORE COMPACT THIS EVENING. WHILE OBS HAVE MAINLY SHOWED LIGHT
   SNOWFALL THROUGH MUCH OF THE AFTERNOON INTO EARLY EVENING
   HOURS...SNOWFALL RATES OF 1-2 INCHES PER HOUR ARE EXPECTED TO
   DEVELOP BETWEEN 03-06Z AND CONTINUE THROUGH THE OVERNIGHT HOURS.
   FURTHER SOUTH ACROSS THE MCD AREA...A WINTRY MIX IS MORE LIKELY
   THROUGH AT LEAST MIDNIGHT BEFORE TRANSITIONING TO FREEZING RAIN.
   
   A CONSOLIDATING BAND OF SNOWFALL ACROSS CNTRL/NRN LOWER MI IS
   EXPECTED TO PRODUCE 1-2 INCH PER HOUR SNOWFALL TONIGHT AS FORCING
   FOR ASCENT INCREASES THROUGH MID LEVELS WITH THE APPROACH OF LOW
   PRESSURE SYSTEM FROM THE WEST. 00Z MESOANALYSIS INDICATED INCREASING
   FRONTOGENESIS AT 850 MB AND 700 MB ATOP SFC BAROCLINIC ZONE FROM
   NWRN WI INTO SERN MI. ADDITIONALLY...FORCING WILL FURTHER BE
   SUPPORTED BY A COUPLED JET AROUND 500 MB LEADING TO DIVERGENCE
   ALOFT. AS ISENTROPIC UPGLIDE OVER WARM FRONT /SITUATED FROM SFC LOW
   OVER S-CNTRL IA INTO S-CNTRL OH/ CONTINUES TO BRING ABUNDANT
   MOISTURE INTO WARM CONVEYOR BELT...EFFICIENT SNOW PRODUCTION WILL
   PERSIST INTO THE EARLY MORNING HOURS. FORECAST MODELS ALSO SUGGEST
   SOME MODEST INSTABILITY AND STEEP LAPSE RATES THROUGH THE CRYSTAL
   GROWTH ZONE SO PERIODS OF CONVECTIVE SNOW BURSTS CAN NOT BE RULED
   OUT...ALONG WITH PERHAPS A LIGHTNING STRIKE.
   
   FURTHER S ACROSS THE MCD AREA...WARMER TEMPERATURE PROFILES WILL
   LEAD TO A GREATER THREAT FOR MIXED PRECIP TYPES THROUGH AT LEAST
   06Z. THEREAFTER...HI-RES HRRR MODEL SUGGESTS A TRANSITION TO
   FREEZING RAIN. FORECAST RUC SOUNDINGS INDICATE A WARM NOSE JUST
   ABOVE 850 MB OF AROUND 6 C WITH SFC TEMPERATURES HOVERING NEAR OR
   JUST BELOW FREEZING. THIS AREA WILL CERTAINLY BE MORE TRICKY AS THE
   AMOUNT OF LOW LEVEL WAA VERSUS WET BULB COOLING AFFECTS WILL PLAY A
   ROLE IN PRECIPITATION TYPE.
   
   ..STOPPKOTTE.. 03/23/2011
   
   
   ATTN...WFO...DTX...APX...GRR...
   
   LAT...LON   45278642 45478561 45418468 45218363 44968299 44558258
               44268231 43608212 43138211 42698213 42458262 42518328
               42578407 42878551 43158640 43638695 44168733 45278642