MESOSCALE DISCUSSION 0059
   NWS STORM PREDICTION CENTER NORMAN OK
   0904 PM CST MON JAN 31 2011
   
   AREAS AFFECTED...PORTIONS SWRN...CENTRAL AND NERN OK...NW TX.
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 010304Z - 010900Z
   
   BAND OF FREEZING RAIN AND SLEET...WITH MORE PURELY FREEZING RAIN ON
   ITS SRN/ERN FRINGES AND SLEET ON WRN FRINGES...IS EXPECTED TO
   MOVE/EXPAND NEWD FROM NW TX ACROSS CENTRAL OK THROUGH 06Z...POSSIBLY
   REACHING PORTIONS NERN OK INVOF TUL AROUND 08-10Z.  ACTIVITY ALSO
   MAY BACKBUILD SWWD SOMEWHAT ACROSS NW TX INTO AREAS E OF LBB AND S
   OF CDS.  ALSO...CONVERSION FROM RAIN TO FREEZING RAIN AND SLEET WILL
   OCCUR WITHIN PORTIONS PRECIP PLUME INITIALLY SE OF FREEZING LINE. 
   EMBEDDED TSTMS MAY PRODUCE LIQUID EQUIVALENT RATES BRIEFLY REACHING
   0.5-0.75 INCH/HOUR RANGE...BUT WITH .10-.25 INCH/HOUR RATES MORE
   COMMON.
   
   DEEP SHORTWAVE TROUGH -- ANALYZED ON 00Z UPPER-AIR CHARTS OVER
   CENTRAL/NRN NM...IS EXPECTED TO MOVE EWD TO W TX BY ABOUT
   09Z...PRECEDED BY EXTENSIVE AREA OF MIDLEVEL DCVA AND LOW-LEVEL WAA
   ABOVE COLD BOUNDARY LAYER.  SFC ANALYSIS SHOWS COLD FRONT CONTINUING
   TO MOVE SWWD ACROSS NRN HILL COUNTRY OF CENTRAL TX...AS WELL AS
   CONCHO VALLEY AND PERMIAN BASIN.  FREEZING AND WET-BULB 0 LINES
   LIKEWISE WILL MOVE SWD BENEATH PROGRESSIVELY MORE OF PRECIP PLUMES
   NOW SPREADING NEWD FROM NW TX AND FROM ABI AREA.  TIME SERIES OF
   FCST SOUNDINGS SUGGESTS COMBINATION OF ELEVATED MOISTURE
   TRANSPORT...FRONTOGENETIC FORCING AND ISENTROPIC ASCENT WILL MOISTEN
   COLUMN IN MOST OF 700-850 MB LAYER AND KEEP IT SUPERFREEZING...WHILE
   RAPIDLY INCREASING LAYER RH AND REMOVING CINH IN SUPPORT OF
   CONVECTIVE PRECIP.  MUCAPE 300-500 J/KG IS POSSIBLE...EXTENDING WELL
   INTO ICING LAYERS SUITABLE FOR THUNDER.  DEPTH OF SUPERFREEZING
   LAYER SUGGESTS AMPLE MELTING OPPORTUNITY FOR GRAUPEL AND SNOW
   GENERATED ALOFT...WHICH THEN WOULD FREEZE WITHIN DEEP POST-FRONTAL
   BOUNDARY LAYER.  EXCEPTIONS WILL BE
   1. ON WRN MARGINS OF EXPANDING PRECIP PLUME...ESPECIALLY AFTER
   06Z...WHERE LARGE-SCALE ASCENT/COOLING AHEAD OF APCHG MID-UPPER
   TROUGH COULD KEEP/COOL COLUMN BELOW FREEZING AND FAVOR INCREASING
   PROBABILITY OF SNOW...AND
   2. ON SRN/ERN FRINGES WHERE FRONTAL LAYER MAY REMAIN SHALLOW ENOUGH
   FOR DROPS TO REMAIN LIQUID TO SFC.
   
   ..EDWARDS.. 02/01/2011
   
   
   ATTN...WFO...TSA...FWD...OUN...SJT...LUB...
   
   LAT...LON   34659642 34119716 33289853 33159913 33049981 33370030
               33610042 33910011 35059817 35819692 36149618 36149592
               35679562 34959618 34659642