ZCZC SPCSWOMCD ALL ACUS11 KWNS 280841 SPC MCD 280841 KSZ000-OKZ000-TXZ000-281445- MESOSCALE DISCUSSION 2096 NWS STORM PREDICTION CENTER NORMAN OK 0241 AM CST MON DEC 28 2015 AREAS AFFECTED...PORTIONS OF SERN KS SWD THROUGH PORTIONS OF CNTRL/WRN OK AND INTO PARTS OF WRN NORTH TX CONCERNING...WINTER MIXED PRECIPITATION VALID 280841Z - 281445Z SUMMARY...WINTER MIXED PRECIPITATION WILL INCREASE IN COVERAGE AND INTENSITY FROM PARTS OF SERN KS SWD TO WRN N TX INCLUDING PARTS OF CNTRL/WRN OK DURING THE PRE-DAWN HOURS. THIS ACTIVITY WILL CONTINUE THROUGH THE EARLY MORNING...BEFORE BEGINNING TO TAPER OFF BY THE MID/LATE MORNING HOURS. DISCUSSION...WATER VAPOR LOOPS INDICATE THE CENTER OF A DEEP/COMPACT CYCLONE CROSSING TX HAVING RECENTLY GAINED MORE APPRECIABLE LATITUDE AS IT TRACKS ACROSS TX. A CORRESPONDING DEFORMATION-ZONE PRECIPITATION SHIELD STRETCHES FROM THE TERMINUS OF A BIFURCATING WARM CONVEYOR OVER THE MO OZARKS SWWD TO WRN N TX. THIS ACTIVITY IS BEING FED BY AMPLE MOISTURE FROM A LOBE OF ASCENT/DCVA IMMEDIATELY PRECEDING THE CYCLONE CENTER APPROACHING THE ARKLATEX. THE DEFORMATION-ZONE PRECIPITATION SHIELD IS FORECAST TO PIVOT IN A COUNTERCLOCKWISE FASHION IN RESPONSE TO THE N-OF-E TRACK OF THE PARENT MID-LEVEL CYCLONE...RESULTING IN AN INCREASE IN PRECIPITATION COVERAGE/INTENSITY ACROSS THE DISCUSSION AREA DURING THE PRE-DAWN HOURS. MEANWHILE...A WAVY 32-F SFC ISOTHERM EXTENDS FROM E-CNTRL KS THROUGH THE OKLAHOMA CITY AREA TO NEAR WICHITA FALLS TX. COLD ADVECTION WILL BE RESPONSIBLE FOR A GENERAL SWD/SEWD SHIFT OF THIS ISOTHERM DURING THE NEXT SEVERAL HOURS...YIELDING MIXED PRECIPITATION TYPES. THE 00Z NORMAN OK RAOB AND FORECAST SOUNDINGS SUGGEST ELEVATED WARM-LAYER TEMPERATURES AROUND THE 3-6C RANGE SUPPORTING COMPLETE MELTING OF DESCENDING HYDROMETEORS. HOWEVER...STEEP LAPSE RATES JUST ABOVE THE SFC ARE ASSOCIATED WITH A SHALLOW PBL WHOSE MINIMUM TEMPERATURES AROUND -8C TO -5C MAY HAVE A TENDENCY TO SUPPORT COMPLETE RE-FREEZING OF THESE HYDROMETEORS BEFORE THEY REACH THE SFC -- RESULTING IN SLEET AS OPPOSED TO FREEZING RAIN OWING TO ICE NUCLEATION AT THE TOP OF THE PBL. THIS WOULD ESPECIALLY BE THE CASE NEAR AND W OF THE INTERSTATE 35 CORRIDOR WHERE COOLER WARM-NOSE TEMPERATURES EXIST. HOWEVER...PATCHES OF FREEZING RAIN WILL BE POSSIBLE ACROSS THE AREA. SLEET-ACCUMULATION RATES ON THE ORDER OF AROUND 0.05-0.15 INCH PER HOUR...AND FREEZING-RAIN RATES ON THE ORDER OF 0.02-0.05 INCH PER HOUR WILL BE POSSIBLE WITH THIS ACTIVITY. THIS ACTIVITY SHOULD CONTINUE THROUGH THE EARLY MORNING...BEFORE BEGINNING TO TAPER OFF BY MID/LATE MORNING AS THE EVOLVING EXTRATROPICAL-CYCLONE COMMA HEAD TRACKS NEWD AWAY FROM THE LOCAL AREA. A BRIEF PERIOD OF SNOW MAY ALSO OCCUR IF PRECIPITATION WERE TO LINGER ACROSS PARTS OF THE AREA INTO THE EARLY AFTERNOON IN RESPONSE TO COOLING WITHIN THE ELEVATED WARM LAYER. ..COHEN.. 12/28/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...TSA...TOP...ICT...OUN... LAT...LON 33829827 33839909 34429924 35719878 36999798 38049676 38229597 37929538 37309557 36029647 34629746 33829827 NNNN