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

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000 FXUS64 KMRX 291841 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 241 PM EDT WED JUL 29 2015 .SHORT TERM /TONIGHT AND THURSDAY/... ANOTHER HOT AND HUMID DAY ALONG THE EASTERN EDGE OF A LARGE SUBTROPICAL RIDGE CENTERED OVER THE SOUTHERN PLAINS AND LOWER MISSISSIPPI RIVER VALLEY. TEMPERATURES HAVE SOARED INTO THE LOWER 90S IN MANY AREAS ACROSS THE EASTERN TENNESSEE VALLEY...AND WITH DEWPOINTS IN THE LOW 70S...HEAT INDEX VALUES BETWEEN 100 TO 105 DEGREES ARE COMMON ACROSS MUCH OF THE CENTRAL AND SOUTHERN VALLEY. SOME SCATTERED CONVECTION IS EXPECTED LATER THIS AFTERNOON AND EVENING...FIRST ALONG THE PLATEAU AND MOUNTAINS...BEFORE SPREADING INTO THE VALLEY. HOWEVER...ATTM...MOST OF THE ACTIVITY DOES SEEM TO BE CONFINED TO THE WEST AND SOUTH...SO THIS DEVELOPMENT MAY BE A LITTLE MORE ISOLATED IN NATURE UNTIL THE EARLY EVENING. BY LATE EVENING INTO THE OVERNIGHT HOURS...A VERY WEAK COLD FRONT WILL SLIDE TOWARD THE AREA FROM THE NORTH AND WEST AS THE AFOREMENTIONED RIDGE MOVES WEST. THIS FRONTAL BOUNDARY COULD TRIGGER SOME ADDITIONAL SCATTERED SHOWERS AND STORMS OVERNIGHT INTO THE MORNING HOURS ON THURSDAY AS IT MOVES INTO THE AREA. MODELS SEEM TO SHOW THE THE BEST CHANCE FOR THIS ACTIVITY BEING BETWEEN 06-15Z...BEFORE IT TAPERS OFF AS THE FRONT WASHES OUT AND MOVES EAST OF THE MOUNTAINS. THUS...HAVE TRENDED DRIER WITH THE FORECAST ON THURSDAY...WITH CHANCE POPS CONFINED TO THE EASTERN MOUNTAINS IN THE AFTERNOON. GIVEN THAT THIS IS A FAIRLY WEAK FRONT...TEMPS MAY ONLY BE A DEGREE OR TWO COOLER. .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... A DRIER NORTHWESTERLY FLOW ALONG WITH SURFACE RIDGING OVER THE CENTRAL AND SOUTHERN APPALACHIANS WILL LEAD TO LOWER HUMIDITY AS DEWPOINT TEMPERATURES BACK OFF BY SEVERAL DEGREES RIGHT INTO THE WEEKEND. THE RESULTING SUBSIDENCE AND DRIER AIR WILL KEEP CONVECTION FROM OCCURRING THROUGH ABOUT MONDAY. HOWEVER...THE LOW LEVEL FLOW WILL EVENTUALLY BECOME SOUTHERLY AGAIN BRINGING AN INCREASE IN MOISTURE BY THE MIDDLE OF NEXT WEEK. MODEL FORECASTS INDICATE THAT THE HIGHER MOISTURE LEVELS WILL BE LIFTED IN THE PRESENCE OF AT LEAST A COUPLE SHORT WAVE LENGTH UPPER TROUGHS INCREASING THE CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AND WEDNESDAY. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 76 93 69 91 / 30 30 10 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 74 91 66 88 / 30 30 10 10 OAK RIDGE, TN 74 91 65 88 / 30 30 0 0 TRI CITIES AIRPORT, TN 70 87 62 86 / 40 30 10 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ AMP/TH

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