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

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355 FXUS64 KMRX 030755 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 355 AM EDT TUE MAY 3 2016 .SHORT TERM (TODAY AND TONIGHT)...
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FRONTAL BOUNDARY IS MOVING SLOWLY EAST ACROSS THE REGION EARLY THIS MORNING AND WILL BE OVER WESTERN NORTH CAROLINA BY THIS AFTERNOON. PLENTY OF WRAP-AROUND MOISTURE AND INSTABILITY FOR RE-DEVELOPMENT OF SHOWERS AND ISOLATED THUNDER EAST OF INTERSTATE 75 THIS AFTERNOON. FOR TONIGHT...PLENTY OF BOUNDARY LAYER MOISTURE REMAINS... ESPECIALLY NORTHEAST SECTIONS. SHOWERS WILL DIMINISH...BUT WILL REMAIN POSSIBLE NEAR OROGRAPHIC LIFT AREAS. OVERALL...WILL TREND TOWARD A SLOWER EROSION OF LOW-CLOUDS THROUGH THE FORECAST. .LONG TERM...(WEDNESDAY THROUGH MONDAY)...MODELS CONTINUE TO BE IN DECENT AGREEMENT OVER THE LONG TERM. THE GENERAL THEME IS BELOW AVERAGE TEMPS DUE TO A DEEP TROUGH SWINGING DOWN INTO THE FORECAST AREA. WEDNESDAY WE START THE PERIOD WITH THE UPPER TROUGH JUST STARTING DIG INTO THE AREA WITH THE CENTER OF LOW PRESSURE UP ACROSS THE GREAT LAKES REGION. BY WEDNESDAY AFTERNOON POP CHANCES INCREASE AS 300 MB JET SWINGS IN WITH ADVANCING TROUGH PROVIDING GOOD DIVERGENCE ACROSS THE REGION. DIVERGENCE...INCREASE IN MOISTURE...COLD FRONT...AND STRONG VORTICITY ASSOCIATED WITH UPPER LEVEL LOW ARE ALL FACTORS THAT WILL LEAD TO THE INCREASE IN POP CHANCES. WE ARE SLIGHTLY UNSTABLE DURING THE AFTERNOON HOURS WITH A FEW HUNDRED JOULES OF CAPE SO WILL HAVE THUNDER IN FORECAST. CENTER OF THE LOW SINKS SOUTH WEDNESDAY NIGHT AS TROUGH REALLY DIGS IN WHICH WILL BRING UNSEASONABLE COLD AIR INTO THE REGION. LOWS WEDNESDAY NIGHT WILL BE 5 TO 10 DEGREES BELOW NORMAL. WITH THIS SURGE OF COLD AIR THE HIGHEST ELEVATIONS COULD SEE SOME LIGHT SNOW SHOWERS OVERNIGHT...WITH LITTLE TO NO ACCUMULATION EXPECTED. THURSDAY WE WILL BE IN A POST FRONTAL AIR MASS BUT WRAP AROUND MOISTURE WILL BEGIN TO RE-ENTER OUR NORTHERN AREAS AS THE CENTER OF THE LOW IS LOCATED ACROSS THE VIRGINIAS. WRAP AROUND MOISTURE...STRONG VORTICITY FIELD...AND GOOD UPPER LEVEL DIVERGENCE WILL LEAD TO ANOTHER ROUND OF SHOWERS THROUGHOUT THE DAY. HAVE A PRETTY TIGHT GRADIENT FOR POP CHANCES AS THE BEST MOISTURE EXISTS ACROSS NETN AND SWVA. LIKELY POPS EXIST IN THESE AREAS WITH NO CHANCE OF POPS ACROSS THE FAR SOUTHERN VALLEY. THURSDAY WILL BE OUR COLDEST DAY OF THE LONG TERM WITH HIGHS STRUGGLING TO HIT 50 ACROSS SWVA...MID 50S NETN....NEAR 60 CENTRAL VALLEY...MID 60S SOUTHERN VALLEY. FOR MOST PLACES HIGHS WILL BE AROUND 15 DEGREES BELOW NORMAL BUT AS MUCH AS 20 DEGREES ACROSS NETN AND SWVA. POP CHANCES HOLD IN PLACE ACROSS NETN AND SWVA OVERNIGHT THURSDAY AS THE LOW CONTINUES TO PULL IN MOISTURE ON THE BACK SIDE. ANOTHER CHANCE OF A LIGHT SNOW SHOWER AGAIN POSSIBLE ACROSS THE HIGHEST PEAKS OVERNIGHT...WITH LITTLE TO NO ACCUMULATION. TEMPS WARM BY ABOUT 10 DEGREES ON FRIDAY AS THE LOW BEGINS TO MOVE OFF TO OUR NE. MOSTLY PRECIP FREE FRIDAY AS MOISTURE EXITS WITH THE LOW. HIGH PRESSURE BUILDS IN BRIEFLY ON SATURDAY AND TEMPS WILL BE A FEW DEGREES ABOVE NORMAL. ANOTHER UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT APPROACHES ON SUNDAY BUT JUST BRUSHES OUR REGION. THE GFS AND ECMWF KEEP THE FRONT JUST TO OUR NORTH...SO WILL ONLY INCLUDE SLIGHT CHANCE POPS ACROSS OUR NORTHERN MOST AREAS. FRONT REMAINS STALLED TO OUR NORTH MONDAY WITH HIGH PRESSURE TRYING TO BUILD BACK IN.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 73 51 71 48 / 20 10 40 40 KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 50 67 46 / 30 10 60 50 OAK RIDGE, TN 70 51 68 46 / 20 10 60 50 TRI CITIES AIRPORT, TN 71 49 65 44 / 50 30 60 60
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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