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

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000 FXUS64 KMRX 200704 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 304 AM EDT SAT SEP 20 2014 .SHORT TERM (TODAY AND TONIGHT)...A RIDGE OF HIGH PRESSURE WILL REMAIN ACROSS THE SOUTHERN APPALACHIANS TODAY AND TONIGHT. MAIN CONCERN WILL BE COVERAGE OF FOG THIS MORNING AND TONIGHT. EXPECT FOG TO BE MAINLY CONFINED TO AREA LAKES AND STREAMS. FOLLOWED MOS GUIDANCE CLOSELY. .LONG TERM (SUNDAY THROUGH FRIDAY)...THE COLD FRONT WILL MOVE THROUGH SUNDAY EVENING INTO THE NIGHT...WITH SHOWERS AND THUNDERSTORMS POSSIBLE AHEAD OF THIS FRONT SUNDAY AFTERNOON THROUGH THE EARLY NIGHT. MODELS ARE IN GOOD AGREEMENT THAT THE MAIN AREA OF PRECIP WILL MOVE IN BETWEEN 2 AND 4 SUNDAY AFTERNOON. GFS IS MUCH MORE STABLE WITH THIS LINE MOVING IN...WITH NAM SHOWING ALMOST 2000 J/KG CAPE VALUES. WINDS ARE UNIFORM THROUGHOUT THE ATMOSPHERE...WITH SOME SHEAR IN THE LOW LEVELS. THE NAM ALSO SHOWS DECENT DRY AIR IN THE MIDLEVELS IN THE EARLY AFTEROON WHICH COULD ENHANCE DOWNBURST AND WIND THREATS. THE FRONT SEEMS TO BE A BIT SEPARATE IN TIMING FROM THE UPPER LEVEL DYNAMICS...WITH THE MAIN AREA OF DIVERGENCE FOR OUR AREA AFTER MIDNIGHT...BUT DUE TO THE STRONG FORCING OF THE CONVECTION UPSTREAM...AND THE FACT THAT THE STORMS NOW LOOK TO MOVE IN EARLIER AND TAKE ADVANTAGE OF THAT DAYTIME HEATING...COULD SEE MODERATE TO STRONG STORMS WITH A FEW ISOLATED SEVERE SUNDAY AFTERNOON AND EVENING. MAIN THREATS WITH THESE STORMS IS EXPECTED TO BE MODERATE HAIL...STRONG WINDS...AND LOCALLY HEAVY RAINFALL. BEHIND THIS FRONT...HIGH PRESSURE DEVELOPS OVER THE EASTERN US. DRY CONDITIONS AND MOSTLY CLEAR SKIES WILL QUICKLY TAKE OVER FOR MONDAY...LASTING THROUGH THE END OF THE WORK WEEK. AS THE HIGH PRESSURE MOVES OFF THE EASTERN COAST AROUND FRIDAY...WRAPAROUND MOISTURE WILL BE ADVECTED TOWARDS OUR AREA. COULD SEE THE CHANCE FOR INCREASING CLOUDS AND PRECIP MAINLY IN SOUTHERN PORTIONS OF THE FORECAST AREA...BUT THIS IS TOO FAR OUT TO SAY WITH MUCH CONFIDENCE. TEMPERATURES BEHIND THIS FRONT WILL BE SEVERAL DEGREES BELOW NORMAL. AS THE TROUGH MOVES EAST...NORTH TO NORTHWEST FLOW WILL BE PRESENT BRINGING DOWN AIR FROM THE NORTH. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 86 61 82 59 / 0 0 40 30 KNOXVILLE MCGHEE TYSON AIRPORT, TN 85 61 80 56 / 0 0 40 30 OAK RIDGE, TN 86 60 80 56 / 0 0 40 30 TRI CITIES AIRPORT, TN 83 53 78 52 / 0 0 40 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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