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

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173 FXUS64 KMRX 030917 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 417 AM EST WED FEB 3 2016 .SHORT TERM...
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(TODAY AND TONIGHT)...A COLD FRONT WAS MOVING INTO THE MIDDLE TN REGION EARLY THIS MORNING. OUT AHEAD OF IT RAIN SHOWERS AND ISOLATED THUNDERSTORMS WERE MOVING ACROSS EAST TN AND SURROUNDING AREAS. STRONG WINDS ALOFT AND LIFT AHEAD OF THE FRONT WAS ENHANCING THE SHOWER AND THUNDERSTORM ACTIVITY IN WESTERN SECTIONS OF THE FORECAST AREA PRODUCING STRONG WIND GUSTS ALONG A LINE OF THUNDERSTORMS MOVING ACROSS THE PLATEAU AND TOWARDS THE SOUTHERN VALLEY. LOCALLY HEAVY RAINFALL AMOUNTS OF UP TO ONE INCH PER HOUR WAS CAUSING SOME LOCALIZED FLOODING OVER THE SOUTHERN PLATEAU. ALSO HIGHER WINDS MAY BE CAUSING LOCALIZED WIND DAMAGE TOO. THE THREAT FOR SEVERE STORMS AND FLOODING WILL LAST A FEW MORE HOURS THEN DECREASE AS THE UPPER LEVEL SUPPORT SHIFTS NORTH AND NORTH EAST. AT THE SURFACE A DEEP SURFACE LOW WAS OVER MI THIS MORNING WITH A STRONG COLD FRONT EXTENDING SOUTH INTO MIDDLE TN. A STRONG PRESSURE GRADIENT EXISTED BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEAST US COAST. THE GRADIENT WAS STARTING TO RELAX OVER WESTERN SECTIONS OF THE FORECAST AREA AS THE FRONT APPROACHED BUT WAS STILL STRONG IN THE EAST. A WIND ADVISORY AND HIGH WIND WARNING REMAINS IN EFFECT UNTIL 15Z. STRONG WINDS WILL STILL BE POSSIBLE JUST AHEAD OF THE FRONT WITH AN ORGANIZED AREA OF SHOWERS AND STORMS AS THEY MOVE FROM THE PLATEAU EAST TOWARD THE MOUNTAINS THIS MORNING. TEMPERATURES WERE VERY MILD FOR THIS TIME OF YEAR EARLY THIS MORNING AS SOUTH TO SOUTHEAST WINDS KEPT THE ATMOSPHERE WELL MIXED. THEY RANGED FROM THE MID 50S TO MID 60S. TEMPERATURES WILL RISE ONLY SLIGHTLY AHEAD OF THE FRONT THIS MORNING. TEMPERATURES WILL STEADY OUT LATER TODAY AS THE SHOWERS DECREASE AS THEY MOVE SLOWLY EAST. TEMPERATURES WILL LIKELY FALL IN THE AFTERNOON AS COLD AIR ADVECTION BEGINS BEHIND THE FRONT. EXPECT GRADUAL CLEARING TONIGHT BEHIND COLD FRONT WITH TEMPERATURES FALLING INTO THE MID 30S. .LONG TERM...(THURSDAY THROUGH TUESDAY)... THE BEGINNING OF THE LONG-TERM FORECAST WILL FEATURE COLD AIR ADVECTION MOVING IN BEHIND THE FRONT. MOSTLY SUNNY SKIES WILL RETURN BUT TEMPERATURES WILL BE NEAR NORMAL VALUES WITH HIGHS IN THE 40S ACROSS MOST OF THE AREA. ANOTHER UPPER LEVEL TROUGH MOVES IN LATE THURSDAY INTO EARLY FRIDAY BUT THE PW VALUES WILL BE AROUND 0.1-0.2 INCHES...WHICH IS NEAR THE MINIMAL VALUE FOR EARLY FEBRUARY. THEREFORE...NOT EXPECTING ANY PRECIPITATION FROM THIS UPPER LEVEL SYSTEM. WITH THIS DRY AIR IN PLACE...THURSDAY NIGHT SHOULD BE MOSTLY CLEAR WITH LIGHT WINDS AS SURFACE HIGH PRESSURE MOVES OVER THE AREA. THIS WILL ALLOW FOR IDEAL RADIATIONAL COOLING CONDITIONS WITH TEMPERATURES DROPPING DOWN INTO THE 20S AREAWIDE. HIGH PRESSURE AT THE SURFACE AND ABNORMALLY LOW PW VALUES WILL KEEP THINGS DRY INTO THE WEEKEND. MODELS INDICATE A DEEP CLOSED LOW PIVOTING ACROSS THE SOUTHEASTERN U.S. SATURDAY INTO SUNDAY. A LOW PRESSURE DEVELOPS OFF THE CAROLINA COAST AND THE PRECIPITATION FROM THIS SYSTEM WILL REMAIN WELL OFF TO THE EAST. BIG CHANGES ARE IN STORE FOR THE BEGINNING OF THE WORK WEEK AS A TROUGH RACES QUICKLY OUT OF THE NORTHERN PLAINS INTO THE TENNESSEE VALLEY. COLD AIR WILL SPILL DOWN FROM CANADA WITH THIS SYSTEM. UPPER LEVEL HEIGHTS WILL DECREASE SIGNIFICANTLY AS THE LOW CLOSES OFF ACROSS THE AREA WITH MULTIPLE SHORTWAVE TROUGHS ROTATING THROUGH THE MAIN LOW EARLY NEXT WEEK. MODELS INDICATE A SURFACE LOW MOVING THROUGH THE AREA ON MONDAY AS TEMPERATURES BEGIN TO COOL DOWN WITH THE COLDER AIR ALOFT. MOISTURE WILL SPREAD FROM WEST TO EAST DURING THE DAY WITH TEMPERATURES COOLING. FOR NOW...IT APPEARS IT WILL MAINLY BE A MIX OF RAIN/SNOW IN THE VALLEY THROUGHOUT MUCH OF THE DAY WITH SNOW IN THE HIGHER TERRAIN. THE FREEZING LEVEL WILL BE AROUND 2-3 KFT AND THIS IS WHY THERE WILL BE A MIXTURE OF RAIN/SNOW IN THE VALLEY. BASED ON CURRENT MODEL SOUNDINGS...NOT SEEING ANY INDICATION OF ANY OTHER PRECIP. TYPE OTHER THAN RAIN OR SNOW. THE ATMOSPHERE CONTINUES TO COOL MONDAY AFTERNOON AND BASED ON CURRENT GUIDANCE EXPECT THIS IS WHEN ALL LOCATIONS WILL TRANSITIONS TO SNOW. THE GFS IS SHOWING SOME RATHER IMPRESSIVE LAPSE RATES MONDAY AFTERNOON INTO TUESDAY MORNING WITH 850-500 MB LAPSE RATES OF 6.5- 7.5 C/KM. IS THIS WHERE TO VERIFY...THERE WOULD BE SOME HEAVIER BURST OF SNOW. MODELS INDICATE ANOTHER SHORTWAVE TROUGH MOVING THROUGH TUESDAY THAT COULD BRING ANOTHER ROUND OF SNOW AS A SURFACE LOW TRACKS UP THE EAST COAST. IT IS STILL TOO EARLY TO GET SPECIFIC BUT BASED ON THE LATEST MODELS...IT APPEARS A GOOD 2-4 INCH SNOWFALL ACROSS THE AREA WITH HIGHER AMOUNTS IN THE MOUNTAINS. SNOW BEGINS TO TAPER OFF FROM SOUTHWEST TO NORTHEAST TUESDAY NIGHT INTO WEDNESDAY. PLEASE STAY TUNED TO THE LATEST FORECAST AS THERE ARE STILL MANY MODEL RUNS TO COME BETWEEN NOW AND MONDAY.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 64 35 49 28 / 90 10 0 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 65 35 45 25 / 90 10 10 0 OAK RIDGE, TN 64 35 45 26 / 80 10 0 0 TRI CITIES AIRPORT, TN 62 35 44 24 / 100 10 10 0
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...WIND ADVISORY UNTIL 10 AM EST THIS MORNING FOR CHEROKEE-CLAY. TN...HIGH WIND WARNING UNTIL 10 AM EST THIS MORNING FOR BLOUNT SMOKY MOUNTAINS-COCKE SMOKY MOUNTAINS-JOHNSON-SEVIER SMOKY MOUNTAINS-SOUTHEAST CARTER-SOUTHEAST GREENE-SOUTHEAST MONROE-UNICOI. WIND ADVISORY UNTIL 10 AM EST /9 AM CST/ THIS MORNING FOR ANDERSON-BLEDSOE-BRADLEY-CAMPBELL-CLAIBORNE-EAST POLK- GRAINGER-HAMBLEN-HAMILTON-HANCOCK-HAWKINS-JEFFERSON-KNOX- LOUDON-MARION-MCMINN-MEIGS-MORGAN-NW BLOUNT-NORTH SEVIER- NORTHWEST CARTER-NORTHWEST COCKE-NORTHWEST GREENE-NORTHWEST MONROE-RHEA-ROANE-SCOTT TN-SEQUATCHIE-SULLIVAN-UNION- WASHINGTON TN-WEST POLK. VA...WIND ADVISORY UNTIL 10 AM EST THIS MORNING FOR LEE-RUSSELL-SCOTT- WASHINGTON-WISE. && $$ TD/MA

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