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

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000 FXUS64 KMRX 301912 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 312 PM EDT SAT MAY 30 2015 .SHORT TERM (THIS AFTERNOON THROUGH SUNDAY)...A SLIGHT DRIER AIR- MASS ACROSS THE AREA THIS AFTERNOON WITH DEWPOINTS IN THE UPPER 50S AND LOWER 60S. STILL EXPECT ISOLATED CONVECTION THIS EVENING WITH BEST CHANCES ACROSS THE HIGHER ELEVATIONS AND PLATEAU. FOR TONIGHT...AN ISOLATED STORM IS POSSIBLE...OTHERWISE PARTLY CLOUDY SKY WITH PATCHY FOG POSSIBLE. FOR SUNDAY...SOUTHERLY FLOW INCREASES PULLING DEEPER MOISTURE BACK INTO THE SOUTHERN APPALACHIANS. A SURFACE TROUGH WILL APPROACH THE AREA DURING THE AFTERNOON/EVENING HOURS. END RESULT IS A BETTER CHANCE OF CONVECTION WITH BEST COVERAGE ACROSS THE PLATEAU DUE TO BEING CLOSER TO SURFACE TROUGH AND HIGHER ELEVATION (OROGRAPHIC FORCING). MARGINAL TO MODERATE INSTABILITY WITH CAPES APPROACHING 1000 J/KG WITH A WEAK WIND FIELD. MAIN CONCERNS WILL BE LOCALLY HEAVY RAINFALL/ISOLATED FLASH FLOODING...GUSTY WINDS UP TO 45 MPH AND FREQUENT LIGHTNING. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)...MODELS STILL SHOWING WEAK AND BROAD FRONTAL BOUNDARY DRAPED ACROSS THE REGION SUNDAY NIGHT THROUGH MONDAY NIGHT. ALSO...WEAK UPPER LEVEL 500MB TROUGH WILL ALSO BE IN PLACE WHICH WILL AID IN LIFT. MONDAY LOOKS TO BE THE BEST CHANCE FOR PRECIP THROUGH THE LONG TERM WITH LIKELY POPS. BY TUESDAY IT LOOKS LIKE THE FRONT SHOULD BE JUST EAST OF THE APPALACHIAS BUT BECAUSE OF HOW SLOWLY THE FRONT IS MOVING IT`S HARD TO TELL EXACTLY WHERE IT WILL BE BY THIS TIME. SO FOR SUNDAY NIGHT THROUGH MONDAY NIGHT...EXPECT SCATTERED SHOWERS AND STORMS TO BE IN PLACE ACROSS THE AREA. COVERAGE SHOULD DECREASE THE FURTHER WE GET INTO SUNDAY NIGHT WITH STORMS REDEVELOPING MONDAY AFTERNOON AND COVERAGE AGAIN DECREASING OVERNIGHT MONDAY. FOR THE FIRST FEW HOURS OF THE SUNDAY NIGHT PERIOD AND AGAIN BY MONDAY AFTERNOON...CAPE LOOKS SUPPORTIVE OF A FEW STRONG PULSE TYPE STORMS BUT LACKING SHEAR WILL LIMIT THE SEVERE THREAT. PWS DURING THIS TIME WILL BE OVER THE 75TH PERCENTILE FOR THIS TIME OF YEAR BASED ON CLIMATOLOGY. THESE HIGHER PWS COULD LEAD TO SOME BRIEF PERIODS OF HEAVY RAINFALL. WHILE FLOODING ISN`T ANTICIPATED...STILL KEEP A WATCHFUL EYE FOR QUICK PONDING OF WATER ACROSS LOW LYING AREAS UNDER ANY HEAVY DOWNPOURS. AGAIN...BY TUESDAY THE FRONT SHOULD BE TO OUR EAST...BUT SPOTTY DIURNAL CONVECTION STILL POSSIBLE. BEST CHANCE OF SHOWERS AND STORMS LOOK TO BE ALONG THE SPINE OF THE APPLACHIANS. AFOREMENTIONED 500MB UPPER LEVEL TROUGH IS STILL IN PLACE WEDNESDAY THROUGH FRIDAY AS IT IS CUT OFF FROM THE MAIN FLOW AND IS SLOWLY MEANDERING EAST. OVER THESE THREE DAYS MOISTURE IS MORE LIMITED THAN EARLIER IN THE WEEK AS WE ARE IN POST FRONTAL AIRMASS SO ONLY SPOTTY DIURNAL CONVECTION IS ANTICIPATED AT THIS TIME. BY SATURDAY THE TROUGH HAS FINALLY MOVED OFFSHORE AND WEAK RIDGING IS TAKING PLACE WHICH IN TURN YIELDS THE WARMEST DAY OF THE LONG TERM WITH TEMPS IN THE LOW TO UPPER 80S. DIURNAL CONVECTION AGAIN POSSIBLE SATURDAY. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 67 84 65 82 / 30 60 50 50 KNOXVILLE MCGHEE TYSON AIRPORT, TN 67 84 64 81 / 20 50 50 60 OAK RIDGE, TN 67 85 64 81 / 20 50 50 60 TRI CITIES AIRPORT, TN 62 85 62 79 / 20 50 50 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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