Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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000 FXUS64 KMRX 180846 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 346 AM EST THU DEC 18 2014 .SHORT TERM... LITTLE BIT OF A TRICKY FORECAST FOR THE EARLY PART OF TODAY. WEAK RIPPLE OF ENERGY, COMBINED WITH JUST ENOUGH MOISTURE, AND TEMPS RIGHT AROUND FREEZING, IS LEADING TO THE POTENTIAL FOR SOME WINTRY MIX FOR THE WESTERN PARTS OF THE FORECAST AREA. SEEING REPORTS OF LIGHT FREEZING RAIN, SLEET, SNOW, AND RAIN IN WESTERN AND CENTRAL TENNESSEE. THINK THAT AREAS ALONG THE CUMBERLAND PLATEAU AND THE WESTERN TENNESSEE VALLEY HAVE A CHANCE TO SEE SOME OF THIS AS WELL. PRETTY GOOD LAYER OF WARM AIR ABOVE THE SURFACE THAT SHOULD LEAD TO LIQUID PRECIP BEFORE IT NEARS THE SURFACE WHERE TEMPS ARE AT OR BELOW FREEZING EARLY THIS MORNING. THINK THAT SNOW IS A POSSIBILITY IN THE NORTHERN AREAS, BUT MOISTURE IS RELATIVELY LIMITED IN THE DENDRITIC GROWTH ZONE, SO AT THIS TIME BELIEVE ANYTHING THAT FALLS WILL MOST LIKELY BE LIQUID OR FROZEN. DRY AIR ABOVE THE BOUNDARY LAYER WILL ALSO BE OF INTEREST AS IT COULD IMPEDE THE EASTWARD PROGRESS OF THE SYSTEM. HAVE ISSUED AN SPS TO ADVISE PEOPLE ON THEIR MORNING COMMUTE OF THE HAZARDS ASSOCIATED WITH FREEZING RAIN AND SLEET. SURFACE TEMPS SHOULD WARM UP ABOVE FREEZING ACROSS THE AREA BY MID MORNING AND ANY PRECIP THAT IS ABLE TO LINGER AROUND SHOULD REMAIN IN THE FORM OF RAIN. .LONG TERM (FRIDAY THROUGH WEDNESDAY)... A WEAK RIDGE OF HIGH PRESSURE WILL KEEP THINGS DRY FRIDAY...BUT A FAST MOVING SYSTEM ACROSS THE GULF COAST STATES WILL PULL THROUGH THE AREA FRIDAY NIGHT AND SATURDAY MORNING. MAIN DYNAMICS IS FROM THE LEFT ENTERANCE REGION OF THE JET ALONG WITH ISENTROPIC LIFT. TEMPERATURE PROFILE SUGGEST MAINLY RAIN...BUT ACROSS SOUTHWEST VIRGINIA AND NORTHEAST TENNESSEE MOUNTAINS...RAIN WILL MIX WITH OR CHANGE TO SNOW. LITTLE ACCUMULATION EXPECTED. WEAK SURFACE RIDGING AGAIN FOR SUNDAY...BUT THE SOUTHERN STREAM WILL PULL MOISTURE BACK INTO THE SOUTHERN APPALACHIANS FOR SUNDAY NIGHT AND MONDAY AHEAD OF A STRONG NORTHERN STREAM TROUGH. THE NORTHERN STREAM TROUGH WILL DEVELOP A LONG-WAVE TROUGH OVER THE EASTERN TWO-THIRDS OF THE NATION FOR MID-WEEK OR CHRISTMAS DAY. RAIN INITIALLY TUESDAY NIGHT WILL CHANGE TO SNOW ON CHRISTMAS EVE. NORTHWEST FLOW SNOWFALL POSSIBLE ACROSS THE HIGHER ELEVATIONS. SNOW SHOWERS ARE POSSIBLE MOST LOCATIONS CHRISTMAS EVE. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 49 32 49 37 / 20 0 10 70 KNOXVILLE MCGHEE TYSON AIRPORT, TN 47 29 48 34 / 20 0 0 60 OAK RIDGE, TN 47 29 47 33 / 20 0 0 60 TRI CITIES AIRPORT, TN 44 26 45 30 / 20 10 0 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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