MESOSCALE DISCUSSION 0123
   NWS STORM PREDICTION CENTER NORMAN OK
   0403 AM CST THU MAR 05 2015

   AREAS AFFECTED...PARTS OF NORTHEAST/CENTRAL LA AND CENTRAL
   MS/NORTHERN AL

   CONCERNING...WINTER MIXED PRECIPITATION 

   VALID 051003Z - 051500Z

   SUMMARY...AT LEAST LIGHT ICE ACCUMULATIONS/GLAZING ARE EXPECTED TO
   OCCUR WITH FREEZING RAIN/SOME SLEET ACROSS PARTS OF
   NORTHEAST/CENTRAL LA INTO CENTRAL MS/NORTHERN AL AS PRECIPITATION
   RATES INCREASE /UP TO 0.05-0.10 IN PER HR/ AND COLDER SUB-FREEZING
   AIR ARRIVES BY MID/LATE MORNING.

   DISCUSSION...AN AMPLIFYING UPSTREAM UPPER TROUGH/UPPER-JET ENTRANCE
   REGION WILL CONTINUE TO CONTRIBUTE TO PRECIPITATION ACROSS THE
   REGION...INCLUDING A TRANSITIONAL CORRIDOR OF INCREASING WINTER
   MIXED PRECIPITATION ACROSS PARTS OF NORTHEAST/CENTRAL LA INTO
   CENTRAL MS/NORTHERN AL THROUGH MID/LATE MORNING. WITHIN THE
   POST-FRONTAL ENVIRONMENT...THE SURFACE WET-BULB 32F ISOLINE
   CONTINUES TO STEADILY SPREAD SOUTHWARD THIS MORNING...EXTENDING FROM
   JUST SOUTH OF I-20 IN NORTHERN LA INTO NORTH-CENTRAL MS BETWEEN
   GREENWOOD/COLUMBUS TO NORTHERN AL NEAR HUNTSVILLE AS OF 09Z.

   AVAILABLE OBSERVATIONS AND VARIOUS SHORT-TERM FORECAST SOUNDINGS
   SUGGEST THAT FREEZING RAIN/SOME SLEET SHOULD BECOME THE DOMINANT
   PRECIPITATION TYPE GENERALLY BY THE 13Z-15Z TIME FRAME ACROSS MUCH
   OF THIS CORRIDOR. THIS WILL BE OWING TO AN ELEVATED WARM LAYER
   /BETWEEN 850-700 MB/ ATOP SOUTHEASTWARD-TRANSITIONING SUB-FREEZING
   AIR. FURTHERMORE...THE APPROACH OF UPSTREAM CONVECTION...WITH
   SCATTERED THUNDERSTORMS ONGOING ACROSS FAR EAST TX/NORTHERN LA INTO
   WEST-CENTRAL MS DURING THE PREDAWN HOURS...WILL CONTRIBUTE TO BURSTS
   OF HEAVIER MIXED PRECIPITATION INCLUDING SOME LOCALLY HEAVIER
   POCKETS OF ICING AND POTENTIALLY CONVECTIVELY RELATED SLEET. AT
   LEAST LIGHT ICE ACCUMULATIONS/GLAZING CAN BE EXPECTED ACROSS THIS
   CORRIDOR THROUGH MID/LATE MORNING...PARTICULARLY ON ELEVATED AND
   METAL SURFACES.

   ..GUYER.. 03/05/2015


   ATTN...WFO...BMX...HUN...MEG...JAN...LCH...SHV...

   LAT...LON   34768580 34098602 33498735 32648856 31309201 32399241
               34668675 34768580