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

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000 FXUS64 KMRX 220900 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 400 AM EST MON DEC 22 2014 .SHORT TERM (TODAY AND TONIGHT)...
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SURFACE HIGH PRESSURE WILL REMAIN TO OUR NORTHEAST...WHILE LOW PRESSURE IN THE PLAINS WILL TRACK TOWARD THE WESTERN GREAT LAKES. A COLD FRONT WILL BEGIN APPROACHING FROM THE WEST. WEAK ISENTROPIC LIFT MAINLY NORTHEAST EARLY THIS MORNING WILL MOVE OUT. SOUTHERLY LOW LEVEL JET WILL STRENGTHEN TONIGHT...BRINGING INCREASING MOISTURE BUT FORCING STILL NOT IMPRESSIVE OVERNIGHT. ANY MORNING LIGHT RAIN OR DRIZZLE NORTHEAST EXPECTED TO END. A SHOWER MAY MOVE INTO THE SOUTH THIS AFTERNOON...AND WILL CARRY SLIGHT CHANCE TO CHANCE POPS ALL AREAS TONIGHT. ALL LIQUID PRECIP IN THE SHORT TERM. MAV TEMPS GENERALLY LOOK REASONABLE SO WILL STAY CLOSE. .LONG TERM (TUESDAY THROUGH SUNDAY)...IT LOOKS LIKE IT WILL BE WET FOR THE FIRST COUPLE OF DAYS OF THE EXTENDED FORECAST AS THE ADVERTISED HIGHLY AMPLIFIED UPPER TROUGH LUMBERS SLOWLY EAST FROM THE PLAINS TO THE APPALACHIANS FROM 12Z TUESDAY THROUGH 12Z CHRISTMAS DAY. AS IT DOES SO THE UPPER SYSTEM WILL DEEPEN AS IT SHIFTS NORTHEAST FROM THE MID MISSISSIPPI VALLEY INTO THE EASTERN GREAT LAKES. WARM AND MOIST AIR WILL STREAM NORTH INTO THE FORECAST AREA AHEAD OF A FRONTAL BOUNDARY THAT WILL TAKE ITS SWEET TIME MAKING IT ONTO THE CUMBERLAND PLATEAU. SHOWERS SHOULD BE WIDESPREAD ACROSS THE PLATEAU THROUGH THE MORNING ON TUESDAY PROGRESSING EAST ACROSS MUCH OF THE REMAINDER OF THE FORECAST AREA BY TUESDAY EVENING. STILL LOOKS LIKE THERE WILL BE AN AREA OF STRONG DOWNSLOPE FLOW ACROSS NORTHEAST TENNESSEE INTO SOUTHWEST VIRGINIA SLOWING THE ONSET OF SHOWERS OR KEEPING THE CHARACTER OF RAIN RATHER SPOTTY AND LIGHT THROUGH MUCH OF THE DAY. IN ADDITION THE WARMING SHOULD BE REALIZED AT THE SURFACE WHICH SHOULD MAKE THIS LOCATION THE WARMEST SPOT IN THE FORECAST AREA ON TUESDAY WITH HIGH TEMPERATURES IN THE LOW 60S. STILL LOOKS LIKE THERE COULD BE ENOUGH INSTABILITY FOR THE DEVELOPMENT OF A FEW EMBEDDED THUNDERSTORMS IN THIS REGIME...BUT MAINLY LIMITED TO WESTERN AND SOUTHERN SECTIONS. THE COLD FRONT WILL BE A GOOD SIX HOURS SLOWER THAN PREVIOUS FORECAST THINKING WHICH WILL REALLY LIMIT THE POTENTIAL FOR MUCH IN THE WAY OF SNOW. THE RAIN SHOWERS SHOULD REALLY TAPER OFF FROM WEST TO EAST BEHIND THE FRONT AS THE DAY PROGRESSES ON WEDNESDAY WITH MODELS CONTINUING TO SHOW SUBSIDENCE ALONG WITH DECREASING DEPTH OF MOISTURE ACROSS THE REGION. AN AREA OF DEEPER MOISTURE SWINGS BACK EAST INTO THE SOUTHERN APPALACHIANS LATER WEDNESDAY EVENING INTO CHRISTMAS MORNING BUT THE ARRIVAL OF THE COLDEST AIR FOR THE PRODUCTION OF SNOW WILL SLOWER THAN PREVIOUS MODEL DEPICTION. THEREFORE...THERE MAY BE A BRIEF PERIOD LATE CHRISTMAS EVE INTO EARLY CHRISTMAS MORNING WHERE THERE MAY BE A COUPLE FLURRIES OF SNOW IN THE GREAT VALLEY MAINLY NORTH OF I-40. EVEN THE HIGHER TERRAIN...ABOVE 3000 FEET...ACROSS SOUTHWEST VIRGINIA AND NORTHEAST TENNESSEE MAY ONLY PICK UP AROUND AN INCH OF SNOW BEFORE THE SYSTEM IS ENTIRELY GONE BY ABOUT NOON ON CHRISTMAS DAY. WE SHOULD STAY DRY FROM THURSDAY EVENING THROUGH MOST OF THE DAY FRIDAY WITH A FAIRLY DECENT CHANCE AT SEEING A LENGTHY PERIOD OF SUNSHINE ON FRIDAY. MODELS STILL NOT ENTIRELY ON THE SAME PAGE FOR THE END OF THE EXTENDED FORECAST WITH ANOTHER UPPER TROUGH AND COLD FRONT BRINGING A FEW MORE SHOWERS FRIDAY NIGHT INTO SUNDAY AFTERNOON. TEMPERATURES MAY BE COLD ENOUGH FOR A CHANCE FOR SOME LIGHT SNOW...MAINLY HIGHER TERRAIN SATURDAY NIGHT INTO SUNDAY.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 53 46 56 51 / 20 50 90 100 KNOXVILLE MCGHEE TYSON AIRPORT, TN 54 43 59 48 / 10 30 70 100 OAK RIDGE, TN 55 43 57 48 / 10 30 80 100 TRI CITIES AIRPORT, TN 52 38 60 45 / 20 20 50 100
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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