MESOSCALE DISCUSSION 0087
   NWS STORM PREDICTION CENTER NORMAN OK
   0528 AM CST FRI FEB 04 2011
   
   AREAS AFFECTED...PORTIONS NE TX...SERN OK...CENTRAL/SRN
   AR...CENTRAL/NRN LA...CENTRAL/NRN MS...EXTREME SWRN TN...EXTREME
   NWRN AL.
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 041128Z - 041700Z
   
   FREEZING RAIN WITH GEN .05-.10 INCH/HOUR RATES SHOULD CONTINUE OVER
   BROAD SWATH FROM S-CENTRAL LA NEWD ACROSS W-CENTRAL
   MS...MOVING/EXPANDING NEWD OVER MORE OF N-CENTRAL AND CENTRAL MS
   THROUGH ABOUT 16Z.  EMBEDDED CONVECTIVE BURSTS...SOME WITH
   THUNDER...BRIEFLY WILL OFFER .10-.25 INCH/HOUR FREEZING RAIN RATES. 
   FREEZING RAIN WILL GRADE TO SNOW WWD ACROSS PORTIONS EXTREME
   N-CENTRAL/NWRN LA AND S-CENTRAL/SERN AR.  SNOW RATES MAY REACH 1
   INCH/HOUR IN HEAVIEST EMBEDDED BANDS AND SWATHS WWD ACROSS RED RIVER
   REGION OF NE TX AND SWRN OK...SWD TO NEAR I-20.
   
   BROAD PLUME OF PRECIP RELATED TO ELEVATED WAA/ASCENT AND MOISTURE
   TRANSPORT ALOFT IS EXPECTED TO EXPAND NEWD ACROSS ARKLATEX
   RETION...AR...AND MS AT FASTER RATE THAN ITS GENESIS REGION SHIFTS
   EWD ONLY VERY SLOWLY ACROSS LA AND E TX.  LARGE-SCALE ASCENT RELATED
   TO DCVA...IMMEDIATELY PRECEDING MID-UPPER CYCLONE THAT IS EJECTING
   NEWD FROM W TX...ALSO WILL CONTRIBUTE TO ASCENT OVER WRN PORTIONS OF
   DISCUSSION AREA.  NET EFFECT SHOULD BE EXPANSION OF ONGOING PRECIP
   PLUME...WHILE WET-BULB EFFECTS LEAD TO ADDITIONAL BOUNDARY-LAYER
   COOLING OVER MUCH OF THIS AREA.  MODIFIED RUC/ETA-KF FCST SOUNDINGS
   INDICATE NEARLY 9 KFT DEEP SUPERFREEZING LAYER OVER PORTIONS SRN
   MS...TRENDING TO AROUND 4-5 KFT OVER CENTRAL LA AND DISAPPEARING
   OVER E TX AND NWRN LA...IN GOOD AGREEMENT WITH CURRENT TRANSITION
   ZONE FROM FREEZING RAIN TO SNOW.  THIS TRANSITION ZONE...WHICH ALSO
   CORRESPONDS TO SATURATION/LIFT NEAR BASE OF DENDRITIC GROWTH LAYERS
   ALOFT...SHOULD DRIFT EWD ACROSS NRN LA AND SRN AR.  LTG DETECTION
   EQUIPMENT ALSO HAS OBSERVED CG STROKES DURING PAST HOUR FROM MORE
   DISCRETELY CELLULAR CONVECTION FORMING INVOF POE...AND MOVING
   RAPIDLY NEWD BEFORE MERGING INTO BROADER PRECIP PLUME.  MODIFIED
   FCST SOUNDINGS SUGGEST THIS ACTIVITY IS ROOTED AROUND 650 MB --
   ABOVE SUPERFREEZING LAYER BUT WELL WITHIN RANGE WHERE SUPERCOOLED
   LIQUID DROPS ARE BEING PROCESSED THROUGH AN LFC...BENEATH MUCAPE
   100-200 J/KG.
   
   ..EDWARDS.. 02/04/2011
   
   
   ATTN...WFO...BMX...HUN...MEG...JAN...LIX...LZK...LCH...SHV...
   TSA...FWD...OUN...
   
   LAT...LON   34579602 35029543 34829232 35198986 35028819 34568769
               33688801 32348877 31139048 30559238 32039445 32519580
               33629628 34579602