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

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000 FXUS64 KMRX 070826 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 326 AM EST SUN FEB 7 2016 .SHORT TERM /TODAY AND TONIGHT/... HIGH PRESSURE IS IN PLACE ACROSS THE REGION EARLY THIS MORNING...AS CLOUD COVER HAS COMPLETELY DISSIPATED. THIS WILL ALLOW FOR AMPLE SUNSHINE LATER TODAY...AND COMBINED WITH THE SOUTHERLY WINDS...PUSH HIGH TEMPERATURES WELL INTO THE LOW TO MID 50S OVER MUCH OF THE VALLEY. THESE CONDITIONS WILL BE SHORT-LIVED AS AN UPPER-LEVEL DISTURBANCE WILL SHIFT IN FROM THE NORTHWEST...BRINGING A COLD FRONT INTO THE TENNESSEE VALLEY LATE TONIGHT INTO MONDAY MORNING. CLOUDS WILL INCREASE AFTER SUNSET AND LIGHT PRECIPITATION WILL BEGIN TO MOVE IN AFTER MIDNIGHT. TEMPERATURES WILL DROP TO BELOW FREEZING ALONG THE CUMBERLAND MOUNTAINS AND NORTHERN PLATEAU LATE TONIGHT...AND INTO THE 32 TO 35 DEGREE RANGE ACROSS THE REST OF THE VALLEY. TEMPERATURES ALOFT WILL COOL DRAMATICALLY AND THIS WILL SUPPORT LIGHT SNOW TO OCCUR IN THE 06-12Z TIMEFRAME...WITH SOME LIGHT ACCUMULATIONS POSSIBLE IN AREAS THAT ARE BELOW FREEZING. LOCATIONS ACROSS THE CENTRAL AND SOUTHERN VALLEY WILL LIKELY EXPERIENCE LIGHT RAIN...WITH A LITTLE BIT OF SNOW MIXED AROUND DAYBREAK...WITH NO ACCUMULATIONS EXPECTED. PLEASE SEE THE SPS FOR MORE DETAILS ABOUT THE EXPECTED WINTER WEATHER. .LONG TERM /MONDAY THROUGH SATURDAY/... THE MAIN WEATHER STORY WILL CONTINUE TO BE DEVELOPING LONG-WAVE TROUGH OF LOW PRESSURE ACROSS THE EASTERN HALF OF THE NATION. THE DEEP LONG-WAVE TROUGH REMAINS HOLD ACROSS THE SOUTHERN APPALACHIANS THROUGH EARLY THURSDAY MORNING. THE GFS/ECMWF ARE FAIRLY CONSISTENT WITH BEST JET DYNAMICS MOVING THROUGH MONDAY AS FRONTAL BOUNDARY MOVES THROUGH...ESPECIALLY EARLY IN THE MORNIN. STEEPENING LAPSE RATES WILL ALSO BE A BIG FACTOR FOR MONDAY AFTERNOON AND TUESDAY AS COLD AIR ALOFT MOVES ACROSS THE REGION. LOW-LEVEL CAPES MONDAY WILL BE BETWEEEN 100- 150 J/KG AND 50-75 J/KG TUESDAY. WIDESPREAD SHOWERS ARE EXPECTED. FOR MONDAY...LOW-LEVEL VERTICAL TEMPERATURE PROFILE WILL FAVOR A MIXTURE OF RAIN/SNOW LOWER ELEVATIONS/PLATEAU AND ALL SNOW HIGHER TERRAIN. AS A GOOD DEAL OF MIXING OCCURS MONDAY AFTERNOON DUE TO SHOWERS...LOW-LEVEL TEMPERATURE PROFILE WILL COOL QUICKLY WITH PRECIPITATION CHANGING TO SNOW AREA-WIDE. MODEL SHOW FAIRLY DEEP LOW-LEVEL MOISTURE THROUGH TUESDAY NIGHT WITH COLD AIR SQUEEZING OUT MOISTURE IN THE FORM OF SNOW SHOWERS AND FLURRIES. LONG DURATION OF EVENT WILL FAVOR MORE OF AN ADVISORY FOR MOST LOCATIONS BEGINNING LATE MONDAY THROUGH TUESDAY NIGHT. FOR THE HIGHEST ELEVATIONS...SUCH AS SMOKY MOUNTAINS AND HIGH KNOB...VA... TOTAL ACCUMULATIONS OVER 48-60 HOURS WILL BE BETWEEN 4 AND 8 INCHES. WILL HIGHLIGHT THIS WITHIN THE HWO AND SPS. DUE TO COLD AIR ADVECTION MONDAY...DID NOT FOLLOW TYPICAL DIURNAL CURVE. HAVE HIGHS IN THE MORNING...THEN DROPPING DURING THE AFTERNOON. BESIDES THE SNOW...COLD 850MB TEMPERATURES AND MAINLY OVERCAST SKIES WILL PRODUCE UNSEASONABLY COLD CONDITIONS. HIGHS WILL BE SOME 15 TO 20 DEGREES BELOW NORMAL WITH LOWS 5 TO 10 DEGREES BELOW FOR TUESDAY AND WEDNESDAY. FOR WEDNESDAY AND WEDNESDAY NIGHT...WRAP-AROUND MOISTURE BEGINS TO LIFT OUT OF THE AREA FROM SOUTHWEST TO NORTHEAST. WILL MAINTAIN CHANCE OF SNOW SHOWER OR FLURRIES ACROSS SOUTHWEST VIRGINIA AND NORTHEAST TENNESSEE. SURFACE RIDGING AND DRIER NORTHWEST FLOW WILL PRODUCE DRIER CONDITIONS FOR THE REST OF THE EXTENDED. A SLOW MODERATION OF TEMPERATURES ARE EXPECTED AS UPPER TROUGH LIFTS NORTHEAST. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 56 35 45 27 / 0 40 50 40 KNOXVILLE MCGHEE TYSON AIRPORT, TN 54 34 42 26 / 0 50 60 60 OAK RIDGE, TN 54 33 43 25 / 0 60 60 50 TRI CITIES AIRPORT, TN 50 29 41 25 / 0 40 70 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ AMP/DH

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