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

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000 FXUS64 KMRX 280741 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 341 AM EDT THU AUG 28 2014 .SHORT TERM...(TODAY AND TONIGHT)...DECIDED TO ADD PATCHY FOG TO FORECAST FOR EARLY THIS MORNING FOR PORTIONS OF CENTRAL AND NORTHERN PLATEAU AS LATEST OBS INDICATE AN AREA OF HIGHER DEWPOINTS. ALSO ADDED IN SOME CLOUDS TO THE NORTHERN PORTION OF OUR VA COUNTIES AS SHOWERS HAVE BEEN DISSIPATING OVER THE PAST FEW HOURS JUST TO THE NORTH BUT CLOUD COVER WILL CONTINUE TO ADVANCE SOUTHWARD. REGARDING THE REST OF TODAY...NOT MUCH CHANGE FROM PREVIOUS FORECAST. A WEAK FRONTAL BOUNDARY ASSOCIATED WITH A TROUGH OVER NEW ENGLAND WILL BE APPROACHING THE KY/TN LINE BY AROUND 12Z THIS MORNING AND WILL MOVE FURTHER DOWN INTO THE CENTRAL/NORTHERN VALLEY BY THIS AFTERNOON. MODELS STILL SHOWING ISOLATED CONVECTION MAY DEVELOP ALONG THIS BOUNDARY DURING THE AFTERNOON HOURS. SOUNDINGS NOT OVERLY MOIST BUT ENOUGH MOISTURE PRESENT TO SUPPORT CONVECTION. CAPES WILL BE MORE THAN SUFFICIENT WITH VALUES ROUGHLY AROUND 2000 J/KG BY THIS AFTERNOON. WIND PROFILES QUITE WEAK FOR TODAY SO THIS SHOULD PREVENT ANY ORGANIZED STORMS. ANY STORMS THAT DEVELOP WILL HAVE A SLOW STORM MOTION DUE TO WEAK WIND PROFILES. MOVEMENT SHOULD BE IN THE 5 TO 10 MPH RANGE. HAVING SAID ALL THAT...WILL STILL KEEP SLIGHT CHANCE POP IN PLACE ACROSS THE NORTHERN VALLEY AND HIGH TERRAIN AREAS. AGAIN...BEST CHANCE OF SEEING AN ISOLATED STORM WILL BE ALONG THE BOUNDARY AND ALSO ACROSS THE TERRAIN....BECAUSE OF DIURNAL HEATING AND OROGRAPHIC LIFT. AREAS FROM KNOXVILLE AND SOUTH SHOULD STAY DRY...ESPECIALLY DOWN TOWARD CHATTANOOGA. FOR TEMPS...CONTINUED TO STAY CLOSER TO THE SLIGHTLY LOWER NAM MOS FOR MAX TEMPS TODAY. .LONG TERM...(FRIDAY THROUGH WEDNESDAY)...THE MAIN CHALLENGE THIS FORECAST PERIOD WILL BE DETERMINING HOW STRONG THE RIDGE ALONG THE EAST COAST REMAINS THROUGH THE WEEKEND. TONIGHT/S MODEL RUNS INDICATE THAT SHORTWAVES WILL BE FARTHER WEST AFFECTING MIDDLE TN MORE THAN E TN. HOWEVER...LOW LEVEL SOUTHWESTERLY FLOW SHOULD INDUCE SOME OROGRAPHIC SHOWERS AND STORMS TO DEVELOP OVER SW VA...NORTHERN TN PLATEAU FRIDAY AFTERNOON AND A LITTLE MORE SCATTERED ACROSS THE ENTIRE AREA ON SATURDAY. THE WEAKNESS IN THE RIDGE BY SUNDAY SHOULD BE ENOUGH TO BRING THE HIGHEST CHANCES FOR SHOWERS AND THUNDERSTORMS TO THE FORECAST AREA...DIMINISHING SOMEWHAT BY MID EVE. LOWER CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 93 67 92 68 / 10 10 10 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 91 66 90 67 / 10 10 10 10 OAK RIDGE, TN 91 66 90 66 / 10 10 10 10 TRI CITIES AIRPORT, TN 89 60 88 63 / 10 10 10 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SR/AC

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