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

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000 FXUS64 KMRX 260735 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 335 AM EDT SAT JUL 26 2014 .SHORT TERM (TODAY THROUGH SUNDAY NIGHT)...
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CURRENT SURFACE ANALYSIS SHOWS AN AREA OF HIGH PRESSURE CENTERED OVER THE CENTRAL APPALACHIANS...WITH A QUASI-STATIONARY FRONTAL BOUNDARY OVER CENTRAL GA AND THE EASTERN FOOTHILLS OF THE SOUTHERN APPALACHIANS. THIS BOUNDARY IS PROGGED TO MOVE NORTHWARD AS A WARM FRONT ACROSS THE FORECAST AREA TODAY...BUT MODEL SOUNDINGS INDICATE A CAPPED ATMOSPHERE OVER THE FORECAST AREA WHICH SHOULD SUPPRESS ANY POSSIBLE CONVECTIVE DEVELOPMENT ALONG THIS FRONT. A COLD FRONT OVER THE UPPER MS RIVER VALLEY THIS MORNING WILL MOVE SOUTHEASTWARD TODAY...AND IS EXPECTED TO TRIGGER AN MCS OVER THE MID WEST BY THIS EVENING. THIS MCS SHOULD THEN MOVE EAST-SOUTHEASTWARD OVER THE UPPER OHIO RIVER VALLEY TONIGHT...AND MAY AFFECT SOUTHWEST VA AND NORTHEAST TN BEFORE AND SHORTLY AFTER SUNRISE ON SUNDAY MORNING. AS A RESULT...SOME STRONG TO SEVERE CONVECTION MAY BE POSSIBLE OVER THESE AREAS ON SUNDAY MORNING...WITH THE POSSIBILITY OF DAMAGING WINDS AND LOCALLY HEAVY RAINFALL. MODELS ARE IN GOOD AGREEMENT THAT AN UNSEASONABLY STRONG UPPER-LEVEL TROUGH WILL AMPLIFY OVER THE EASTERN HALF OF THE NATION ON SUNDAY BEHIND THIS COLD FRONT...WHICH WILL HELP TO CREATE A MODERATELY UNSTABLE AIR MASS AND STRONG WIND FIELD OVER THE FORECAST AREA BY SUNDAY AFTERNOON AND EVENING. LAPSE RATES APPEAR TO BECOME FAIRLY STEEP THROUGHOUT THE TROPOSPHERE OVER THE FORECAST AREA BY SUNDAY AFTERNOON AND EVENING...WITH 0-3 KM HELICITY VALUES CONDUCIVE FOR TORNADO DEVELOPMENT (AROUND 300 M2/S2). THUS...IT APPEARS THAT THERE WILL LIKELY BE A GOOD COVERAGE OF SEVERE CONVECTION OVER THE FORECAST AREA SUNDAY AFTERNOON AND EVENING...WITH THE POSSIBILITY OF WIDESPREAD DAMAGING WINDS...VERY LARGE HAIL...LOCALLY HEAVY RAINFALL...AND ISOLATED TORNADOES. AS FOR TEMPS...GFS AND NAM GUIDANCE NUMBERS ARE IN GOOD AGREEMENT WITH MINS FOR TONIGHT AND SUNDAY NIGHT...BUT REVEAL SOME DISCREPANCIES WITH MAXES FOR TODAY AND SUNDAY. WILL GENERALLY TREND TOWARDS THE COOLER NAM MAXES SINCE THIS HAS BEEN THE TREND LATELY...AND AN EXPECTED INCREASE IN MOISTURE AND CONVECTIVE ACTIVITY SHOULD CONTINUE THIS TREND. .LONG TERM (MONDAY THROUGH FRIDAY)...PERSISTENT TROUGHING WILL KEEP COOLER THAN NORMAL CONDITIONS THROUGH THE NEW WORK WEEK. SHOULDN/T SEE MUCH IN THE WAY OF ORGANIZED OR SIGNIFICANT PRECIP AFTER THE MONDAY MORNING FRONTAL PASSAGE...BUT SOME LOW POPS WILL BE POSSIBLE AT TIMES. BEYOND THE VALID PERIOD...MAY ACTUALLY GET A BROAD CLOSED LOW OVER THE OHIO VALLEY NEXT WEEKEND...WHICH MAY MAKE US A LITTLE MORE SHOWERY. STAY TUNED.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 91 71 92 72 / 0 0 30 50 KNOXVILLE MCGHEE TYSON AIRPORT, TN 89 70 90 71 / 0 20 30 60 OAK RIDGE, TN 89 70 90 71 / 0 20 30 60 TRI CITIES AIRPORT, TN 88 66 89 67 / 0 30 40 60
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DMG/GC

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