ZCZC SPCSWOMCD ALL ACUS11 KWNS 270938 SPC MCD 270938 OKZ000-KSZ000-TXZ000-271545- MESOSCALE DISCUSSION 2076 NWS STORM PREDICTION CENTER NORMAN OK 0338 AM CST SUN DEC 27 2015 AREAS AFFECTED...PORTIONS OF WRN OK AND ADJACENT PARTS OF FAR SRN KS AND NWRN TX CONCERNING...WINTER MIXED PRECIPITATION VALID 270938Z - 271545Z SUMMARY...WINTER MIXED PRECIPITATION WILL INCREASE IN INTENSITY ACROSS PORTIONS OF WRN OK DURING THE PRE-DAWN HOURS...AN CONTINUE THROUGH THE MORNING. THIS INCLUDES FREEZING RAIN...ALONG WITH AREAS OF SLEET. DISCUSSION...WIDESPREAD...CONVECTIVELY GENERATED PRECIPITATION OVER CNTRL TX IS ADVANCING NNEWD TOWARD/ACROSS THE RED RIVER VALLEY WHERE ANTECEDENT COLD ADVECTION AND WET-BULB-COOLING HAVE SUPPORTED THE INFLUX OF SUB-FREEZING SFC TEMPERATURES. SFC OBSERVATIONS FROM THE OK MESONET AND ASOS SITES INDICATE THE 32-F ISOTHERM ROUGHLY EXTENDING FROM NEAR MEDFORD...TO KINGFISHER...TO HOBART...TO ALTUS -- EXTENDING NEWD INTO S-CNTRL KS AND SWWD INTO WRN NORTH TX. LOW-LEVEL MASS FIELDS WELL N OF A DEEP CYCLONE -- WHOSE PRECEDING ASCENT IS ENCOURAGING THE CONVECTIVE DEVELOPMENT -- WILL SUPPORT LITTLE OVERALL CHANGE IN THE 32-F ISOTHERM DURING THE NEXT SEVERAL HOURS. HOWEVER...SFC OBSERVATIONS SUGGEST SOME SLIGHT COLD ADVECTION ONGOING ACROSS WRN OK...WHICH COULD RESULT IN A SLIGHT SWD/SEWD SHIFT IN THIS ISOTHERM ACROSS SWRN OK. ELEVATED WARM-LAYER TEMPERATURES AROUND 2-5 C WILL RESULT IN PARTIAL TO COMPLETE MELTING OF DESCENDING HYDROMETEORS...WHICH WILL RE-FREEZE TO THE W/NW OF THE 32-F ISOTHERM RESULTING IN FREEZING RAIN AND AREAS OF SLEET. PRESENT INDICATIONS ARE THAT FREEZING-RAIN RATES OF 0.05-0.10 INCH PER HOUR WILL BE POSSIBLE WITH THIS ACTIVITY...ALONG WITH SLEET-ACCUMULATION RATES AROUND 0.10-0.25 INCH PER HOUR. THE HIGHEST OF THESE RATES -- AND EVEN LOCALLY HIGHER ONES -- MAY ACCOMPANY LIGHTNING-PRODUCING CONVECTION PARTICULARLY INVOF THE RED RIVER VALLEY WHERE SLEET MAY BE MORE PREDOMINANT. ALL OF THIS ACTIVITY...WILL BECOME PREVALENT FROM SSW TO NNE IN THE NEXT FEW HOURS...AND CONTINUE THROUGH THE MORNING. ALSO OF NOTE...VERY STRONG NLY WINDS -- WITH GUSTS OF 40-55 MPH COMMON -- WILL AFFECT THE AREA -- PARTICULARLY ALONG AND S OF INTERSTATE 40. THIS WILL HAVE THE POTENTIAL TO ENHANCE DAMAGE TO TREE LIMBS AND POWER LINES ON WHICH ICE ACCUMULATES. ..COHEN.. 12/27/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...ICT...OUN...DDC...LUB...AMA... LAT...LON 36469743 35479788 34399888 34159934 34209999 34330017 34790019 35959952 36689891 37119828 37149754 36799741 36469743 NNNN