MESOSCALE DISCUSSION 0068
   NWS STORM PREDICTION CENTER NORMAN OK
   1142 AM CST TUE FEB 01 2011
   
   AREAS AFFECTED...PORTIONS OF SRN/E-CNTRL MO...CNTRL IL...CNTRL IND
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 011742Z - 012245Z
   
   MODERATE TO HEAVY MIXED PRECIPITATION WILL EXPAND EWD ACROSS
   PORTIONS OF THE LOWER GREAT LAKES AND OHIO VALLEY REGION THROUGH
   22Z. SIGNIFICANT ICING...WITH FREEZING RAIN RATES AOA 0.25 INCH PER
   3 HOURS...WILL BE A CONCERN IN THE SRN HALF OF THE DISCUSSION
   AREA...WITH SLEET EXPECTED FURTHER NORTH.
   
   A POWERFUL EXTRATROPICAL CYCLONE CONTINUES TO MATURE OVER THE CNTRL
   CONUS...WITH A WELL-DEFINED/INTENSE WARM CONVEYOR BELT IN THE ERN
   SEMICIRCLE OF THE CYCLONE. THE 15Z RUN OF THE RUC INDICATES A SLY
   850-MB JET MAX WITH CORE WINDS OF 70 KT OVER PORTIONS OF THE LOWER
   OH VALLEY AND MID-SOUTH. THIS IS SUPPORTING STRONG NWD TRANSPORT OF
   DEEP-LAYER MOISTURE...WITH AMSU/SSMI TOTAL PRECIPITABLE WATER
   PRODUCT INDICATING AN INFLUX OF PWAT VALUES AROUND 1.5 INCHES NOSING
   INTO THE LOWER MS VALLEY REGION. DEEP-LAYER ASCENT ASSOCIATED WITH
   THE WARM CONVEYOR BELT RISING ATOP THE COLD AIR MASS ENTRENCHED
   ACROSS THE OHIO VALLEY REGION WILL BE AUGMENTED BY INTENSE
   UPPER-LEVEL DIVERGENCE EXPECTED TO RESULT FROM A COUPLED JET STREAK
   STRUCTURE LATER THIS AFTERNOON. AS PRECIPITATION FALLS INTO A
   NEAR-SURFACE SUB-FREEZING LAYER AT LEAST 60 STATUTE MILES NORTH OF
   THE OH RIVER...MIXED PRECIPITATION TYPES ARE EXPECTED THIS
   AFTERNOON. 
   
   ACROSS THE SRN HALF OF THE DISCUSSION AREA WHERE LOW-LEVEL WARMING
   WILL BE STRONGEST...TEMPERATURES AOA 3C IN THE ELEVATED WARM LAYER
   WILL SUPPORT COMPLETE MELTING OF HYDROMETEORS. FREEZING RAIN IS 
   ANTICIPATED IN THIS REGION...AS THE PRECIPITATION INTERACTS WITH
   SUB-FREEZING SFC TEMPS. HEAVY FREEZING RAIN WILL BE POSSIBLE...AS
   THE 12Z NAM MODEL INDICATES UPRIGHT INSTABILITY ENTERING THE REGION
   IN ASSOCIATION WITH THE WARM CONVEYOR BELT. THE ASSOCIATED
   CONVECTIVE ENHANCEMENT...POTENTIALLY ACCOMPANIED BY LIGHTNING...WILL
   ALLOW LIQUID-EQUIVALENT TO EXCEED 0.25 INCH PER 3 HOURS PER THE HRRR
   MODEL. THIS WILL LIKELY RESULT IN SIGNIFICANT ICING.
   
   ACROSS THE NRN HALF OF THE DISCUSSION AREA...TEMPERATURES IN THE
   ELEVATED WARM LAYER ARE EXPECTED TO REMAIN BELOW 3C...ALLOWING ONLY
   PARTIAL HYDROMETEOR MELTING...WITH MAINLY SLEET EXPECTED. THE NAM
   MODEL INDICATES SLANTWISE INSTABILITY SPREADING E/NEWD ACROSS THIS
   REGION...SUGGESTING THE POTENTIAL FOR MESOSCALE BANDING AND LOCALLY
   HEAVY SLEET RATES.
   
   ..COHEN/ROGERS.. 02/01/2011
   
   
   ATTN...WFO...ILN...LMK...IWX...IND...PAH...LOT...ILX...LSX...
   SGF...
   
   LAT...LON   40218485 39278488 38868546 38718701 38518807 37718987
               37039099 36679165 36739239 37499251 38139199 38999083
               40218832 40778565 40218485