MESOSCALE DISCUSSION 0046
   NWS STORM PREDICTION CENTER NORMAN OK
   0633 PM CST FRI JAN 12 2007
   
   AREAS AFFECTED...CNTRL MO...CNTRL IL...FAR SERN KS...FAR NWRN
   AR...FAR NERN OK
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 130033Z - 130530Z
   
   A SIGNIFICANT ICE STORM WILL CONTINUE THROUGH MUCH OF THE EVENING
   HOURS NW OF A QUASI-STATIONARY ARCTIC FRONT. ICE ACCUMULATIONS OF
   .05 TO .10 IN/HR WILL REMAIN LIKELY. LOCALIZED RATES UP TO .25 IN/HR
   WILL ALSO OCCUR AT TIMES.
   
   A NEARLY STEADY-STATE MIXED PRECIPITATION EVENT IS EXPECTED TO OCCUR
   OVER THE NEXT SEVERAL HOURS ACROSS THE MCD AREA...AS A WARM/MOIST
   CONVEYOR BELT HAS BECOME WELL-ESTABLISHED FROM THE LOWER RIO GRANDE
   N/NEWD TOWARDS THE MID-MS RIVER VALLEY. LOW-LEVEL WARM THETA-E
   ADVECTION/ISENTROPIC LIFT ATOP A NEAR-SURFACE BASED COLD DOME WILL
   AID IN THE CONTINUED PRODUCTION OF MIXED PRECIPITATION. 18Z NAM/GFS
   AND 21Z RUC GUIDANCE ARE CONSISTENT WITH STRENGTHENING THE LLJ THIS
   EVENING FROM NERN TX INTO SRN MO AND SRN IL...WITH CORRESPONDING
   INCREASES IN QPF AS WELL.
   
   AT 00Z...THE SURFACE FREEZING LINE WAS LOCATED FROM AROUND FYV TO
   STL TO BMI. THIS BOUNDARY SHOULD PROGRESS VERY SLOWLY SWD IN THE
   OZARKS REGION...WITH MORE SUBSTANTIAL PROGRESS SEWD IN SRN IL WITH
   GREATER PRESSURE RISES. 00Z SGF AND ILX OBSERVED SOUNDINGS INDICATE
   FREEZING RAIN WILL REMAIN THE PREDOMINANT PTYPE CENTERED ALONG THE
   I-44 CORRIDOR ACROSS MO /INCLUDING THE STL METRO AREA/ NEWD INTO
   CNTRL IL. FURTHER NWWD...THE PTYPE WILL REMAIN MOSTLY SLEET FROM
   AROUND CNU NEWD TO SZL AND UIN. HERE...A LARGER NEAR-SURFACE COLD
   LAYER WILL REMAIN BENEATH A SMALLER ABOVE-FREEZING LAYER COMPARED TO
   LOCALES FURTHER SE.
   
   ..GRAMS.. 01/13/2007
   
   
   ...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...LOT...ILX...LSX...DVN...LZK...SGF...EAX...TSA...TOP...ICT...
   
   37359570 38079547 38859468 39769337 40439202 41039013
   41298912 41048824 40438813 39428871 38778950 38099064
   37029257 35839394 36069497