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

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000 FXUS64 KMRX 291858 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 258 PM EDT FRI MAY 29 2015 .SHORT TERM (TONIGHT AND SATURDAY)...
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SOUTH TO SOUTHWEST FLOW SURFACE TO ALOFT IS PULLING PLENTY OF MOISTURE INTO THE SOUTHERN APPALACHIANS. AIR-MASS IS MARGINALLY UNSTABLE PRODUCING SCATTERED CONVECTION OVER THE AREA THIS AFTERNOON. CONVECTION WILL DISSIPATE SOON AFTER SUNSET DUE TO LOSS OF HEATING AND LACK OF SYNOPTIC FORCING. MAIN CONCERN WITH STORMS WILL BE HEAVY RAIN...GUSTY WINDS UP TO 40 MPH AND FREQUENT LIGHTNING. DUE TO MID AND HIGH CLOUDS CLEARING OVERNIGHT AND SCATTERED RAIN THIS AFTERNOON/EVENING...PATCHY DENSE FOG IS EXPECTED BY EARLY SATURDAY MORNING. FOR SATURDAY...MODEL SOUNDINGS SHOW A DRIER AIRMASS OVER THE REGION WITH UPPER RIDGING A LITTLE STRONGER OVER THE SOUTHERN APPALACHIANS. END RESULT WILL BE MUCH SMALLER COVERAGE OF CONVECTION AND MAINLY CONFINED TO THE HIGHER TERRAIN. .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)...MODELS DIFFER SLIGHTLY ON TIMING OF PRECIP SUNDAY AS A WEAK FRONT MAKES ITS WAY IN TO THE AREA. STORMS THAT FORM WEST OF THE AREA SATURDAY NIGHT ALONG AN AREA OF WEAK CONVERGENCE COULD CONTINUE TO MOVE EAST THROUGH THE EARLY MORNING...AFFECTING THE PLATEAU COUNTIES. OTHERWISE...SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM EARLY AFTERNOON ACROSS MAINLY THE HIGHER ELEVATIONS...AND MOVE IN TO THE VALLEY. STRONG TO POSSIBLY ISOLATED SEVERE ARE POSSIBLE WITH THESE STORMS...ALTHOUGH AS MORE DETAILS APPEAR...CONFIDENCE WILL INCREASE. WIND PROFILE FOR SUNDAY IS VERY WEAK...SO STORMS THAT DO FORM WOULD MOVE SLOWLY...BUT BE VERY SHORTLIVED. INSTABILITIES AVERAGE AROUND 2000 J/KG WITH SLIGHTLY HIGHER AMOUNTS IN NORTHERN HALF OF CWA. ALSO IN NORTHERN HALF OF CWA...LARGE AMOUNTS OF DRY AIR IN THE MID AND UPPER LEVELS WILL CAUSE CONCERN AND THREAT OF STRONG DOWNBURST WINDS IN THESE STORMS. SOUTHERN HALF OF CWA DOES NOT HAVE THE AMOUNT OF MID AND UPPER LEVEL DRY AIR...BUT THREAT OF STRONG DOWNBURST WINDS WILL STILL BE PRESENT. HAIL THREAT WILL BE MINIMAL WITH HIGH FREEZING LEVELS. BUT WITH THE SLOW MOVING NATURE OF THE STORMS...LOCALIZED FLASH FLOODING COULD BE AN ISSUE...ESPECIALLY IN ANY STORMS THAT MOVE OVER THE SAME AREA. SUNDAY NIGHT THE CONVECTION IS EXPECTED TO WEAKEN SLIGHTLY...WITH CONVECTION MAINLY LIMITED TO THE HIGHER ELEVATIONS IN EAST TENNESSEE. MONDAY...SHOWERS AND THUNDERSTORMS ARE EXPECTED TO AGAIN DEVELOP IN THE EARLY AFTERNOON AS THE FRONT REMAINS OVER THE AREA. LARGE AMOUNTS OF INSTABILITY...BUT VERY MOIST PROFILE...COULD AGAIN SEE THREAT OF STRONG WINDS AND SMALL HAIL. MAIN THREAT HOWEVER WILL BE LOCALIZED FLOODING WITH HEAVY RAINFALL AMOUNTS IN THE STORMS THAT DO FORM. THIS IS ALL ASSUMING THE SOUTHERN FLOW CAN CONTINUE TO BRING AMPLE MOISTURE IN TO THE AREA. MODEL RUNS THE PAST COUPLE OF WEEKS HAVE BEEN CONSISTENTLY TOO WET...BUT RIGHT NOW WILL LEAVE IN FLOODING THREAT. MONDAY NIGHT WILL AGAIN SEE STORMS THAT WEAKEN AND MOVE OUT OF THE AREA...WITH A FEW SHOWERS POSSIBLE IN THE HIGHER ELEVATIONS OF EAST TENNESSEE. TUESDAY...THE WEAK FRONT FINALLY MOVES EAST OF THE AREA...AND WINDS WILL SHIFT TO THE NORTHWEST BEHIND IT. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL REMAIN CLOSE TO THE MOUNTAINS OF EAST TENNESSEE. BY WEDNESDAY...LOW PRESSURE TRIES TO DEVELOP OVER THE GULF STATES. WITH FLOW AROUND THE LOW...MOSITURE WILL BE ADVECTED FROM THE SOUTH TO SOUTHEAST IN TO THE AREA. DEPENDING ON THE POSITION OF THE LOW...DEPENDS ON HOW MUCH MOISTURE WE GET IN TO THE AREA. WITH THE LARGE DIFFERENCE BETWEEN MODEL RUNS LATELY...CONFIDENCE IS LOW ON TIMING AND COVERAGE OF CONVECTION FORMING EACH AFTERNOON. WILL LEAVE IN SLIGHT CHANCE FOR DIURNAL SHOWERS AND THUNDERSTORMS FORMING...WITH PROMISE TO EDIT AS MODELS BECOME MORE CONSISTENT. TEMPERATURES WILL REMAIN NEAR NORMAL AND VERY STATIC THROUGH THE EXTENDED.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 66 86 66 81 / 20 20 20 50 KNOXVILLE MCGHEE TYSON AIRPORT, TN 64 86 65 80 / 20 10 20 50 OAK RIDGE, TN 65 87 65 80 / 20 10 20 50 TRI CITIES AIRPORT, TN 62 85 62 78 / 20 20 20 60
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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