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

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000 FXUS64 KMRX 072019 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 319 PM EST SUN FEB 7 2016 .SHORT TERM (TODAY THROUGH TUESDAY)... WEATHER THROUGH THE REMAINDER OF THE DAY WILL BE PLEASANT WITH MOSTLY SUNNY SKIES AND HIGHS TOPPING OUT IN THE 50`S ACROSS MUCH OF THE AREA. THINGS WILL QUICKLY START TO CHANGE OVERNIGHT AS A LOW MOVES ACROSS THE GREAT LAKES REGION AND THE ASSOCIATED COLD FRONT SWEEPS THROUGH OUR AREA. CLOUD COVERAGE WILL INCREASE AFTER THE SUN HAS SET AND PRECIPITATION WILL MOVE IN FROM THE NORTHWEST. TEMPERATURES ALOFT WILL COOL MUCH MORE QUICKLY COMPARED TO SURFACE TEMPS AND THIS WILL BE THE BIGGEST CONCERN WITH REGARDS TO PRECIPITATION TYPE. IF THE SURFACE COOLS OFF QUICKER WE WILL SWITCH TO SNOW MUCH FASTER, BUT IF IT DOESN`T AND WE REMAIN SEVERAL DEGREES ABOVE FREEZING THEN IT WILL LIKELY BE RAIN. MODELS ARE IN DISAGREEMENT WITH THE TEMPERATURES NEAR THE SURFACE WITH THE GFS/NAM BEING MUCH COLDER COMPARED TO THE ECMWF AND OTHER MODELS. THIS HAS LEAD TO A LOW CONFIDENCE FORECAST WHEN IT COMES TO THE MONDAY MORNING COMMUTE AS ONLY A COUPLE OF DEGREES COULD MEAN THE DIFFERENCE BETWEEN A WET COMMUTE AND ONE THAT INVOLVES A COUPLE OF INCHES OF SNOW. WITH THAT SATED, WE HAVE GONE AHEAD AND ISSUED A WINTER WEATHER ADVISORY FOR EARLY MONDAY MORNING THROUGH TUESDAY NIGHT. IF TEMPERATURES REMAIN WARM ENOUGH THEN PLACES IN THE ADVISORY AREA MIGHT NOT SEE SNOW UNTIL MONDAY NIGHT...HOWEVER, IF SNOW MOVES IN FASTER OR TEMPERATURES ARE SLIGHTLY COOLER THAN FORECASTED THEN THE MONDAY MORNING COMMUTE COULD BE SNOWY IN SOME PLACES. SO WE HAVE ERRED ON THE SIDE OF CAUTION AND STARTED THE ADVISORY IN THE MORNING ON MONDAY. REGARDLESS, THE TEMPERATURES IN THE VALLEY WILL WARM ENOUGH TO LIKELY SWITCH OVER TO RAIN DURING THE DAYTIME HOURS. WITH THE STEEP LAPSE RATES AND COLD TEMPERATURES ALOFT, IT`S NOT OUT OF THE QUESTION TO HEAR A RUMBLE OF THUNDER DURING THE DAY WITH THE RAINFALL. TROUGH WILL REMAIN OVER THE AREA ALLOWING FOR VERY COLD AIR TO CONTINUE TO INVADE INTO OUR REGION AND TEMPERATURES ON TUESDAY WILL LIKELY REMAIN BELOW FREEZING FOR MANY PLACES. ANY PRECIPITATION THAT DOES OCCUR ON MONDAY NIGHT INTO TUESDAY WILL REMAIN IN THE FORM OF SNOW. QPF DOES LOOK LIGHT WITH THIS EVENT AND THEREFORE WILL RESULT IN A RATHER SLOW SNOWFALL ACCUMULATION DURING THE FIRST PART OF THE WEEK. .LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)...FRIGID WEATHER PATTERN REMAINS IN PLACE WEDNESDAY INTO THURSDAY AS ADDITIONAL ENERGY DROPS SOUTH THROUGH THE BASE OF THE EASTERN U.S. UPPER TROUGH. TEMPERATURES WILL BE WELL BELOW NORMAL BOTH DAYS WITH MAXES REMAINING BELOW FREEZING ACROSS NEARLY THE ENTIRE FORECAST AREA ON WEDNESDAY AND OVER MUCH OF THE NORTHERN TWO THIRDS OF THE REGION ON THURSDAY. LIGHT SNOWFALL STILL POSSIBLE TUESDAY NIGHT EVERYWHERE BUT TRANSITIONS TO MORE OF AN OROGRAPHIC SITUATION IMPACTING MAINLY THE HIGHER TERRAIN OVER SOUTHWEST VIRGINIA AND ALONG THE TENNESSEE AND NORTH CAROLINA BORDER FOR WEDNESDAY. WEDNESDAY NIGHT INTO THURSDAY THERE STILL MAY BE A FEW SNOW SHOWERS POSSIBLE IN THESE MOUNTAIN LOCALES BUT ANY SNOW SHOULD BE OVER FOR THE REMAINDER OF THE FORECAST AREA. MODELS NOT ENTIRELY ON THE SAME PAGE BUT STILL HINT AT AN ALBERTA CLIPPER TYPE SYSTEM FOR THE POSSIBILITY OF SOME LIGHT SNOW AGAIN FRIDAY INTO FRIDAY NIGHT. KEPT SLIGHT AND LOW CHANCE POPS IN FOR THIS POSSIBILITY. SATURDAY AND SUNDAY APPEAR TO BE DRY AT THIS TIME AS THE OFFENDING EASTERN TROUGH MAY FINALLY SHOW SOME SIGNS OF SHIFTING OFF TO THE ATLANTIC. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 35 45 27 32 / 40 50 40 30 KNOXVILLE MCGHEE TYSON AIRPORT, TN 34 42 26 28 / 50 60 60 50 OAK RIDGE, TN 33 43 25 30 / 60 60 50 40 TRI CITIES AIRPORT, TN 29 41 25 28 / 40 70 60 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ ABM/TH

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