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

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000 FXUS64 KMRX 190727 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 327 AM EDT TUE AUG 19 2014 .SHORT TERM (TODAY THROUGH THURSDAY NIGHT)... TODAY...A MOIST ENVIRONMENT WILL REMAIN OVER THE AREA. SHORT TERM MODELS SHOW SOME CONVECTION DEVELOPING DURING THE MORNING IN RESPONSE TO A 500 MB VORT MAX...WITH A LITTLE BETTER COVERAGE IN THE AFTERNOON ONCE WE GET BETTER DESTABILIZATION. WILL HAVE CHANCE POPS AREA WIDE THROUGH THE DAY. MLCAPE VALUES IN THE 1800-2200 J/KG RANGE AND STEEP LOW LEVEL LAPSE RATES COULD RESULT IN SOME STRONG STORMS WITH GUSTY WINDS THIS AFTERNOON. TONIGHT...BETTER RAIN CHANCES SHIFT TO NORTHERN AREAS AS UPSTREAM CONVECTION THAT IS EXPECTED TO DEVELOP THIS AFTERNOON OVER IL/IN TRACKS SE ACROSS KY. THE NAM IS PRETTY AGGRESSIVE IN MAINTAINING THE CONVECTION AS IT MOVES INTO OUR AREA LATE TONIGHT/WED MORNING. IT MAY BE A BIT OVERDONE...BUT WILL RAISE POPS TO HIGH CHANCES NORTH LATE TONIGHT. LINGERING OUTFLOW BOUNDARIES AND GOOD INSTABILITY WILL KEEP A CHANCE OF TSTMS GOING THROUGH THE DAY WEDNESDAY. THE RIDGE OVER MS/AL WILL BUILD NORTHWARD THROUGH THURSDAY...WHICH WILL SHIFT THE AREA OF CONVECTIVE DEVELOPMENT FARTHER NORTH AND EAST TOWARD THE GREAT LAKES/OHIO VALLEY. WITH THE MIDLEVEL STEERING FLOW BECOMING NE...MOST OF THIS UPSTREAM CONVECTION WILL MOVE EAST OF OUR AREA...BUT COULD CLIP OUR NE SECTIONS. WILL KEEP SOME CHANCE POPS IN SW VA/NE TN...BUT SOUTHERN AREAS WILL LIKELY BE CAPPED UNDER THE INFLUENCE OF THE STRONG RIDGE. TEMPERATURES WILL ALSO BE WARMING INTO THE LOWER AND MIDDLE 90S IN THE CENTRAL AND SOUTHERN VALLEY ON THURSDAY. .LONG TERM (FRIDAY THROUGH MONDAY)... THE BIG NEWS IS THAT IT APPEARS THE SOUTHERN APPALACHIAN REGION MAY ACTUALLY SEE AN UPPER RIDGE GRADUALLY BUILD OVER THE REGION FROM WEST THROUGH EAST ABOUT SATURDAY THROUGH MONDAY. THIS SCENARIO WOULD HEAT UP THE FORECAST AREA AND LEAD TO A DRIER REGIME AS SUBSIDENCE DRIES OUT THE ATMOSPHERE...LEAVING ONLY A SLIGHT POSSIBILITY OF CONVECTION ON THE MAJOR TERRAIN FEATURES. PRIOR TO THIS THOUGH...ON FRIDAY...A LONG WAVE TROUGH WILL BE DROPPING SOUTHEAST FROM THE EASTERN GREAT LAKES INTO THE NORTHEASTERN ATLANTIC BY SATURDAY. MODEL FORECASTS SHOW THERE WILL BE A MEDIUM CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS SOUTHWEST VIRGINIA AND NORTHEAST TENNESSEE IN AN AXIS OF DEEPER MOISTURE ALONG A WEAK AIRMASS BOUNDARY WITH SLIGHTLY COOLER AND DRIER AIR EAST AND WARMER AND MORE HUMID AIR TO THE WEST. TWO OR THREE WEAK IMPULSES MAY AID LIFT AS THEY ROUND THE BASE OF THE EASTERN U.S. UPPER TROUGH. KEPT LOWER POPS FOR CENTRAL EAST AND SOUTHEAST TENNESSEE THROUGH THE PERIOD DUE TO FARTHER PROXIMITY FROM THE "RING OF FIRE". STAYED UNDER MEX MOS MAXES AND A LITTLE ABOVE MINS. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 89 71 92 72 / 30 20 30 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 85 69 89 71 / 30 30 40 20 OAK RIDGE, TN 85 69 89 71 / 30 30 40 20 TRI CITIES AIRPORT, TN 83 65 84 65 / 40 30 50 40 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ 24/99

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