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

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000 FXUS64 KMRX 191911 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 311 PM EDT TUE AUG 19 2014 .SHORT TERM...
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(TONIGHT THROUGH TOMORROW)... TONIGHT...THERE MAY BE A FEW ONGOING ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS FROM THIS AFTERNOONS ACTIVITY TO START THE TONIGHT PERIOD. THIS ACTIVITY WILL LINGER AROUND THROUGH PART OF THE NIGHT AS WE STAY RELATIVELY UNSTABLE AND CONTINUE TO HAVE A MOIST ENVIRONMENT. MOST OF THIS ACTIVITY SHOULD STAY IN SHOWER FORM AS WARMER AIR IN THE MIDLEVELS SHOULD PREVENT ANY STRONGER UPDRAFTS FROM DEVELOPING THUS ONLY ALLOWING FOR A STRAY LIGHTNING STRIKE HERE AND THERE. THE BIG QUESTION DURING THIS PERIOD IS REGARDING TOMORROW MORNINGS POTENTIAL ACTIVITY. A LOW PRESSURE SYSTEM OVER THE GREAT LAKES IS SUPPOSED TO GENERATE A LINE OF SHOWERS AND STORMS LATER THIS AFTERNOON ACROSS ILLINOIS AND INDIANA...AND CONTINUE TO PROGRESS SE TOWARD OUR AREA OVERNIGHT. THE NAM SHOWS THIS ACTIVITY FIZZLING OUT BEFORE IT REACHES OUR AREA TOMORROW MORNING BUT THEN REDEVELOPS SHOWERS AND STORMS BY AROUND 15Z ALONG THE FRONT. THE GFS IS A BIT MORE BULLISH AND DOES BRING THE INITIAL ACTIVITY ALL THE WAY INTO OUR AREA. HOWEVER IT UNFOLDS THOUGH...IT DOES LOOK LIKE THERE WILL BE SHOWERS AND STORMS AROUND TOMORROW MORNING...WHETHER IT IS FROM THE INITIAL LINE OR FROM REDEVELOPMENT. MEANWHILE...500MB HEIGHTS ARE QUICKLY BUILDING OVER THE PLAINS AS HIGH PRESSURE IS BEGINNING TO TAKE A STRONG HOLD. THESE BUILDING HEIGHTS WILL FORCE US INTO A NW FLOW PATTERN BY WED AFTERNOON. SHOWERS AND STORMS CONTINUE THROUGH THE AFTERNOON TOMORROW AS THE FRONT MOVES THROUGH. SLIGHTLY COOLER OVERNIGHT LOWS NORTH DUE TO LESS CLOUD COVER BUT STILL WARM. TEMPS IN THE MID TO UPPER 60S NORTH TO NEAR 70 SOUTH. DID INCLUDE PATCHY 2SM MILE FOG AGAIN FOR THE NORTHERN AREAS AND INTO SWVA. WARMER TOMORROW WITH SOUTHERN AREAS LOW 90S...CENTRAL NEAR 90 AND NETN AND SWVA LOW TO MID 80S. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)...THE UPPER LOW OVER THE NE STATES...ASSOCIATED FRONTAL BOUNDARY AND DAYTIME HEATING WILL WARRANT MORE WIDESPREAD POPS EARLY IN THE LONG TERM PERIODS. KEPT THE 40 TO 50 PERCENT CHANCES NORTH DOWN TO 15 TO 20 PERCENT SOUTH. LET RAIN CHANCES DECREASE BY SUNDAY THROUGH TUESDAY AS THE UPPER RIDGE AMPLIFIES FROM THE SE STATES NORTH TO THE OHIO RIVER VALLEY. MODEL FORECAST SOUNDINGS SHOW STEEP LAPSE RATES WITH NOT MUCH OF A CAPPING INVERSION DURING THIS PART OF THE LONG TERM. THUS...CAN`T RULE OUT DIURNAL CONVECTION FOR THOSE DAYS...MAINLY IN THE HIGHER TERRAIN AREAS. FOR TEMPS...WENT CLOSER TO GFS MOS OR A BLEND WITH NAM FOR WEDNESDAY NIGHT TO THURSDAY NIGHT. ADJUSTED MAX TEMPS UP FOR THE WEEKEND TO TUESDAY...IN LINE WITH THE GFSX MOS AND SIMILAR ECMX MOS...GIVEN THE RISING HEIGHTS ALOFT.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 71 92 72 94 / 30 30 10 20 KNOXVILLE MCGHEE TYSON AIRPORT, TN 68 89 71 92 / 30 40 20 30 OAK RIDGE, TN 68 89 71 92 / 30 40 20 30 TRI CITIES AIRPORT, TN 65 85 65 87 / 30 50 40 50
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SR/TG

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