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

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000 FXUS64 KMRX 191855 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 255 PM EDT FRI SEP 19 2014 .SHORT TERM (TONIGHT AND SATURDAY)...CURRENT SURFACE ANALYSIS SHOWS A LARGE DOME OF HIGH PRESSURE CENTERED OVER THE NORTHEAST...WHICH EXTENDS SOUTHWARD ACROSS MOST OF THE EASTERN HALF OF THE NATION. THIS HIGH WILL BRING DRY AND TRANQUIL CONDITIONS OVER THE FORECAST AREA TONIGHT AND SATURDAY...WITH PATCHY FOG EXPECTED TO DEVELOP AGAIN OVERNIGHT...MAINLY AROUND THE WATERWAYS. AS FOR TEMPS...GFS AND NAM GUIDANCE NUMBERS ARE IN GENERAL AGREEMENT WITH MINS FOR TONIGHT...BUT WILL TREND CLOSER TO THE COOLER NAM NUMBERS WHICH HAVE VERIFIED BETTER LATELY. ALSO...WILL TREND COOLER THAN BOTH SETS OF GUIDANCE WITH MAXES ON SATURDAY (WHICH HAS BEEN THE TREND LATELY). .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)...COLD FRONT BRINGING SHOWERS AND STORMS SUNDAY EVENING THEN PLEASANT CONDITIONS THROUGH THE REST OF THE EXTENDED. SATURDAY NIGHT WE HAVE AN APPROACHING UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT TO OUR NW. CONDITIONS OVER OUR AREA WILL REMAINING CALM WITH MOSTLY CLEAR SKIES AND OVERNIGHT LOWS NEAR OR A DEGREE OR TWO ABOVE NORMAL. THE FIRST HALF OF SUNDAY SHOULD BE NICE BUT CLOUDS WILL INCREASE FROM NW TO SE DURING THE MID TO LATE AFTERNOON HOURS AS THE COLD FRONT APPROACHES. CURRENT NAM AND GFS ARE IN GOOD AGREEMENT AS FAR AS TIMING AND SUGGEST THAT SHOWERS AND STORMS WILL ARRIVE ON THE PLATEAU BETWEEN 19 TO 21Z AND THEN SPREAD INTO THE CENTRAL VALLEY BY AROUND 00Z. THE NAM AND GFS DO DIFFER ON THE AMOUNT OF INSTABILITY HOWEVER. AT 00Z SUNDAY THE NAM SHOWS 1500 TO 2000 J/KG OF CAPE ACROSS THE AREA WHILE THE GFS ONLY SHOWS 500 TO 1000 J/KG. OBVIOUSLY IF THE NAM IS CORRECT THEN WE COULD SEE A FEW STRONGER STORMS ACROSS THE AREA. THE STRONGEST STORMS THOUGH SHOULD STAY TO OUR NORTH WHERE THE BEST SHEAR IS...AS THERE IS A TIGHT SHEAR GRADIENT ALONG THE KY/TN STATE LINE. NONETHELESS...IF WE DO HAVE THE INSTABILITY THAT THE NAM SUGGESTS THEN A FEW STRONGER STORMS COULD DRIFT DOWN OUT OF KY INTO TN. AFTER SUNDAY NIGHTS CONVECTION THE REST OF THE EXTENDED LOOKS DRY. SOME CLOUDS MAY LINGER BEHIND THE FRONT SUNDAY NIGHT BUT SKIES SHOULD QUICKLY CLEAR WITH SUNSHINE RETURNING BY LATE MORNING/EARLY AFTERNOON ON MONDAY. COOLER AIR BEHIND THE FRONT WILL KEEP MAX TEMPS IN THE LOW 70S ACROSS SW VA/NE TN...MID 70S CENTRAL VALLEY...AND UPPER 70S SOUTHERN VALLEY ON MONDAY. THE TROUGH PUSHES FURTHER NE ON MONDAY AS HIGH PRESSURE SLOWLY BEGINS TO BUILD BACK IN ACROSS THE AREA. WITH HIGH PRESSURE SLOWLY BUILDING EXPECT A GRADUAL WARMING TREND THROUGH THE WORK WEEK. MOISTURE LOOKS TO RETURN BY FRIDAY/FRIDAY NIGHT ACROSS THE SOUTHERN VALLEY AND SW NC BUT KEPT PRECIP OUT FOR NOW. OVERALL...IT SHOULD BE A VERY PLEASANT EXTENDED PERIOD AFTER THE FRONT MOVES THROUGH SUNDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 63 83 62 83 / 0 0 0 30 KNOXVILLE MCGHEE TYSON AIRPORT, TN 61 81 62 81 / 0 0 0 30 OAK RIDGE, TN 60 81 60 81 / 0 0 0 30 TRI CITIES AIRPORT, TN 55 79 56 79 / 0 0 0 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DMG/SR

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