MESOSCALE DISCUSSION 2192
   NWS STORM PREDICTION CENTER NORMAN OK
   0541 AM CST SUN DEC 09 2007
   
   AREAS AFFECTED...CENTRAL MO/CENTRAL IL/NORTHERN INDIANA/NORTHWEST
   OH/FAR SOUTHERN LOWER MI
   
   CONCERNING...FREEZING RAIN 
   
   VALID 091141Z - 091645Z
   
   MAINLY FREEZING RAIN /WITH POTENTIAL FOR SIGNIFICANT ICE
   ACCUMULATIONS/ WILL STEADILY INCREASE FROM CENTRAL MO AND
   CENTRAL/NORTHEAST IL INTO NORTHERN INDIANA AND FAR SOUTHERN LOWER
   MI/NORTHWEST OH THIS MORNING. THIS INCLUDES A CORRIDOR FROM
   NEAR/NORTH OF ST LOUIS TO SPRINGFIELD/PEORIA/BLOOMINGTON/CHAMPAIGN
   IL TO THE LAFAYETTE/LOGANSPORT/GOSHEN/FORT WAYNE INDIANA AREAS.
   
   WITHIN AN ELEVATED BAROCLINIC ZONE...INCREASING LARGE SCALE FORCING
   FOR ASCENT/ISENTROPIC LIFT WILL LEAD TO A DOWNSTREAM SPREAD OF
   EXISTING PRECIPITATION SHIELD INTO THE REMAINDER OF NORTH
   CENTRAL/NORTHEAST IL AND NORTHERN INDIANA/NORTHWEST OH/FAR SOUTHERN
   LOWER MI THROUGH MID MORNING. PREDAWN SURFACE ANALYSIS FEATURES WET
   BULB 32F LINE RUNNING LARGELY PARALLEL TO INTERSTATE 44 IN
   MO...WHILE REMAINING GENERALLY STEADY-STATE JUST NORTH OF INTERSTATE
   70 FROM ST LOUIS TO INDIANAPOLIS TO DAYTON OH. NORTH OF THIS
   LINE...FREEZING RAIN WILL BE QUITE COMMON AS A SHALLOW /LESS THAN 1
   KM/ COLD AIRMASS EXISTS BENEATH AN ELEVATED WARM/POTENTIALLY
   UNSTABLE AIRMASS ADVECTING INTO THE REGION VIA A MODERATE
   SOUTHWESTERLY LOW LEVEL JET. SIMILAR TO THE LATEST NAM/GFS/RUC
   DETERMINISTIC GUIDANCE AND ASSOCIATED FORECAST SOUNDINGS/PRECIP-TYPE
   ALGORITHMS...LATEST /03Z/ SREF GUIDANCE LENDS STRONG SUPPORT FOR A
   HIGH LIKELIHOOD AND DURATION OF FREEZING RAIN WITHIN THIS CORRIDOR
   THROUGH 18Z. CONSIDERABLE ICE ACCUMULATIONS APPEAR LIKELY THROUGH
   THE MORNING.
   
   STEEP MID LEVEL LAPSE RATE ENVIRONMENT/CONVECTIVELY UNSTABLE AIRMASS
   ALOFT WITH A FEW HUNDRED J/KG MOST UNSTABLE CAPE /PER EVENING
   OBSERVED RAOBS AND LATEST RUC SOUNDINGS/ WILL CONTINUE TO FAVOR
   PRONOUNCED CONVECTIVE ELEMENTS AND ELEVATED THUNDERSTORMS THROUGH
   THE MORNING. WHILE FREEZING RAIN SHOULD REMAIN DOMINANT IN MOST
   LOCALES...THE CONVECTIVE POTENTIAL WILL ALSO PROMOTE OCCASIONAL
   SLEET IN ASSOCIATION WITH THUNDERSTORMS.
   
   ..GUYER.. 12/09/2007
   
   
   ...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...CLE...ILN...DTX...IWX...IND...LOT...ILX...LSX...DVN...SGF...EAX...
   
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