MESOSCALE DISCUSSION 0004
   NWS STORM PREDICTION CENTER NORMAN OK
   1245 PM CST SAT JAN 01 2005
   
   AREAS AFFECTED...CENTRAL/ERN IA...SRN WI AND PORTIONS OF NRN IL
   
   CONCERNING...FREEZING RAIN AND SLEET 
   
   VALID 011845Z - 012245Z
   
   A MIX OF FREEZING RAIN AND SLEET WILL CONTINUE ACROSS THE REGION
   THROUGH AFTERNOON...WITH DEVELOPMENT INTO SCENTRAL WI AND NRN IL
   THROUGH 21Z. HRLY ACCUMULATIONS OF ICE FROM 0.05-0.10 INCHES WILL BE
   POSSIBLE WITH THE HEAVIER CONVECTIVE SHOWERS.
   
   LOW LEVEL ADVECTIVE COMPONENT WILL REMAIN WEAKER THAN FARTHER NORTH
   THUS EXPECT OVERALL LIGHTER ACCUMULATIONS OF FREEZING RAIN/SLEET
   THAN ACROSS FAR NRN IA/MN AND CENTRAL WI. HOWEVER...ISENTROPIC LIFT
   NORTH OF SFC FRONT WILL REMAIN MODERATE AND COMBINED WITH ELEVATED
   INSTABILITY...MUCAPES FROM 50-150 J/KG ...WILL SUPPORT HEAVIER
   CONVECTIVE FREEZING RAIN/SLEET SHOWERS ACROSS THE AREA THROUGH 00Z.
   AN EARLIER BAND OF PRECIPITATION THAT MOVED ACROSS CENTRAL/ERN IA
   INTO SWRN WI HAS ALLOWED FOR SUFFICIENT SATURATION SO THAT ANY
   ADDITIONAL PRECIPITATION WILL BE EFFICIENT IN REACHING THE GROUND.
   LOW LEVEL WAA WILL LEAD TO NWD MOVEMENT OF THE SFC FREEZING LINE
   THROUGH THE AFTERNOON...BUT SINCE SFC LOW MVMNT WILL BE ENEWD INTO
   SERN NEB AND WET-BULB EFFECTS WILL BE OCCURRING...IT IS NOT
   ANTICIPATED THAT THE SFC FREEZING LINE WILL MOVE MUCH NORTH OF I-80
   THROUGH 00Z.
   
   OVER SCENTRAL WI/NRN IL WHERE PRECIPITATION HAS NOT FALLEN MUCH
   TODAY...A DELAY IN LOW-MID LEVEL SATURATION SHOULD PROVIDE FOR 
   SLEET AS THE PREDOMINATE PTYPE FOR THE FIRST HOUR OR SO OF ONSET OF
   PRECIP. PRECIP IS NOT ANTICIPATED TO CHANGE OVER TO FREEZING RAIN
   OVER THE IMMEDIATE CHI METRO AREA...WHERE NELY WINDS OFF LK MI
   SHOULD KEEP TEMPERATURES ABOVE FREEZING.
   
   ..CROSBIE.. 01/01/2005
   
   
   ...NOTICE...
   SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
   SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
   06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
   RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
   USED FROM DECEMBER 1 THROUGH FEBRUARY 28.
   
   ATTN...WFO...LOT...ILX...MKX...DVN...ARX...DMX...
   
   43689076 42909326 42199377 41679346 41259186 41119084
   41118952 41298867 41818767 43488808