MESOSCALE DISCUSSION 0016
   NWS STORM PREDICTION CENTER NORMAN OK
   1206 AM CST TUE JAN 06 2009
   
   AREAS AFFECTED...MID-MS/LOWER OH RIVER VALLEYS
   
   CONCERNING...FREEZING RAIN 
   
   VALID 060606Z - 061000Z
   
   FREEZING RAIN WILL INCREASE IN AREAL COVERAGE AND INTENSITY
   OVERNIGHT. MEAN ICE ACCRETION RATES SHOULD RANGE FROM 0.02 TO 0.05
   IN/HR WITH LOCALIZED CONVECTIVELY-INDUCED RATES AOA 0.10 IN/HR
   POSSIBLE.
   
   EVENING MODEL GUIDANCE ARE FAIRLY CONSISTENT THROUGH 12Z WITH A
   GRADUAL EWD MOVEMENT OF A LEAD MID-LEVEL VORTICITY MAXIMUM
   /CURRENTLY STRETCHING FROM SERN KS TO WRN TX PER WATER VAPOR
   IMAGERY/. ASCENT ASSOCIATED WITH THIS FEATURE HAS LIKELY AIDED IN
   WEAK RADAR ECHOES RECENTLY DEVELOPING OVER THE OZARK PLATEAU. GIVEN
   A BROAD LOW-LEVEL WARM/MOIST ADVECTION REGIME DOWNSTREAM OF THIS
   /PER REGIONAL PROFILERS AND 00Z HAND-ANALYZED UPPER AIR
   CHARTS/...PRECIPITATION INTENSITY/COVERAGE WILL LIKELY INCREASE.
   THIS SCENARIO IS SUPPORTED BY OPERATIONAL NAM/NAMKF/GFS ALONG WITH
   4-KM WRF-NMM. FORECAST SOUNDINGS SUGGEST THE CONTINUED INFLUX OF
   RICHER MOISTURE WOULD RESULT IN WEAK ELEVATED CONVECTIVE INSTABILITY
   DEVELOPING TOWARDS 12Z...ENHANCING PRECIPITATION RATES.
   
   RECENT OBJECTIVE ANALYSIS OF THE SURFACE WET-BULB FREEZING LINE
   INDICATES A NEARLY STATIONARY CONFIGURATION FROM CNTRL AR NEWD TO
   NRN KY. WITH A RELATIVELY BENIGN SURFACE PATTERN LEADING TO MODEST
   WINDS...THIS TREND SHOULD CONTINUE. A SLOW NWD PROGRESSION IS
   POSSIBLE IF WIDESPREAD PRECIPITATION DEVELOPS...RESULTING IN
   SIGNIFICANT DOWNWARD SENSIBLE HEAT FLUX VIA PRECIPITATION FALLING
   FROM WARMER LAYER JUST ABOVE SURFACE.
   
   ..GRAMS.. 01/06/2009
   
   
   ...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...ILN...LMK...IND...PAH...ILX...MEG...LSX...LZK...
   SGF...
   
   LAT...LON   36369133 36939145 37709112 38219023 38838839 39168696
               39438523 39408394 39008372 38578416 38288513 37608695
               36848844 36238953 35849055 35989088 36369133