MESOSCALE DISCUSSION 0205
   NWS STORM PREDICTION CENTER NORMAN OK
   1151 PM CST SAT FEB 24 2007
   
   AREAS AFFECTED...SRN LOWER MI...FAR NERN IND...NRN/CNTRL OH...SWRN
   PA...NRN WV...FAR WRN MD
   
   CONCERNING...FREEZING RAIN 
   
   VALID 250551Z - 250945Z
   
   A LARGE AREA OF FREEZING RAIN...OCCASIONALLY MIXED WITH SLEET...WILL
   EXPAND ENEWD OVERNIGHT. SIGNIFICANT ICE ACCUMULATION RATES AROUND
   .05 TO .15 IN/HR WILL BE LIKELY.
   
   SUBSTANTIAL ICE ACCUMULATIONS HAVE BEEN ONGOING FOR THE PAST SEVERAL
   HOURS ACROSS A GOOD PORTION OF THE CORN BELT AHEAD OF A POTENT
   VERTICALLY-STACKED CYCLONE CENTERED OVER NRN MO. WARM/MOIST
   ADVECTION IN THE LOW/MID-LEVELS AND UPPER-LEVEL DIVERGENCE CONTINUE
   TO AID IN A GRADUAL EXPANSION OF STOUT PRECIPITATION SHIELD FROM SRN
   LOWER LK MI...NRN IND...SRN OH AND SRN WV. IN ADDITION...THE SURFACE
   WET BULB FREEZING LINE HAS BEEN STEADILY PROGRESSING NEWD AROUND 15
   TO 20 KT. 23/21Z SREF GUIDANCE INDICATES THE PREDOMINANT PTYPE WILL
   REMAIN FREEZING RAIN AS THE SHIELD EXPANDS ENEWD...CHANGING TO RAIN
   ON THE SRN EDGE AS LOW-LEVEL WAA CONTINUES. THE SREF SUPPORTS 03Z
   RUC GUIDANCE WHICH IS AROUND 2-3 DEG C WARMER AT 850 MB VERSUS THE
   00Z NAM DURING THE 06-12Z PERIOD...AND DISPLAYS A CORRESPONDINGLY
   LARGER ABOVE FREEZING WARM NOSE IN FORECAST SOUNDINGS.
   
   ACROSS THE WRN PORTION OF THE MCD AREA...WATER VAPOR IMAGERY
   INDICATES A MID/UPPER-LEVEL DRY SLOT IMPINGING NEWD ACROSS IL/MID-MS
   RIVER VALLEY. AS THE NRN MO CYCLONE UNDERGOES FURTHER OCCLUSION
   OVERNIGHT...THIS DRY SLOT SHOULD CONTINUE NEWD AND LEAD TO
   DIMINISHING PRECIPITATION RATES OVER SRN LOWER MI/NERN IND/NWRN OH
   AFTER 09Z.
   
   ..GRAMS.. 02/25/2007
   
   
   ATTN...WFO...CTP...LWX...PBZ...RLX...CLE...ILN...DTX...IWX...GRR...
   
   40607912 39727809 39447818 39077847 38987892 39077958
   39428082 39888200 40938442 41478541 42078623 42378627
   42808612 42948542 42718409 42318315 41458094