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

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517 FXUS64 KMRX 271928 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 328 PM EDT WED APR 27 2016 .SHORT TERM (TONIGHT AND THURSDAY)...
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LOW PRESSURE SYSTEM STILL OVER THE PLAINS WITH ITS TRAILING COLD FRONT MOVING EASTWARD TOWARD THE MISS RIVER. THIS SYSTEM WILL BE HEADING OUR WAY...BUT WILL WEAKEN AS IT MOVES INTO/THROUGH THE AREA. THERE IS ENOUGH INSTABILITY FOR THUNDERSTORMS...AND ENOUGH INSTABILITY AND SHEAR FOR A FEW MARGINALLY SEVERE STORMS TONIGHT AND INTO THURSDAY. THERE IS A WEAK SHORTWAVE MOVING THROUGH TONIGHT TO HELP ORGANIZE STORMS TO MARCH THROUGH THE AREA. THEN ON THURSDAY THE MOISTURE AND SHEAR LINGER...BUT THERE IS LITTLE IN THE WAY OF ORGANIZED LIFT IN THE AREA AND THE LOW LEVEL WINDS VEER AS LEE TROUGHING DEVELOPS IN THE CAROLINAS...SO THE TERRAIN MAY BE NEEDED AS A FOCUS TO GET SOME OF THE CONVECTION GOING EARLY THURSDAY AFTERNOON. MLCAPE WILL LIKELY RISE TO ABOUT 1000 J/KG THURSDAY. THE MAIN THREAT TONIGHT AND THURSDAY WILL BE STRONG OUTFLOW WINDS FROM STRONGER STORM CELLS...ALONG WITH SOME HAIL. WENT CLOSE TO GUIDANCE TEMPS FOR THESE PERIODS. .LONG TERM (THURSDAY NIGHT THROUGH WEDNESDAY)...FAST MOVING SHORT- WAVE AND ASSOCIATED JET STREAK WILL MOVE EAST OF THE AREA THURSDAY AFTERNOON WITH DRIER AIR ADVECTING INTO THE SOUTHERN APPALACHIANS THURSDAY NIGHT. CLEAR SKY AND CALM WINDS WILL ALLOW AREAS/PATCHY FOG TO DEVELOP. RIDGING SURFACE/ALOFT WILL PRODUCE A DRY DAY FOR FRIDAY WITH WARM TEMPERATURES. NEXT SHORT-WAVE WILL MOVE ACROSS THE CENTRAL/SOUTHERN PLAINS FRIDAY NIGHT THEN TOWARD THE LOWER MISSISSIPPI VALLEY SATURDAY. AS BOUNDARY LAYER SOUTHERLY FLOW RETURNS FOR SATURDAY... MOISTURE AND INSTABILITY. MODELS DO SHOW A BROAD AREA OF DIVERGENCE ACROSS THE TENNESSEE VALLEY AND ISENTROPIC LIFT WHICH WILL HELP WITH GREATER COVERAGE OF CONVECTION FOR SATURDAY. FOR SUNDAY...MAIN SHORT-WAVE AND ASSOCIATED JET WILL ENHANCE THE CONVECTON ACROSS THE AREA. MODEL SOUNDINGS SHOW A MUCH MORE ROBUST ENVIRONMENT FOR SEVERE THUNDERSTORMS AS THE WIND FIELD WILL INCREASE. ENHANCED WIND FIELD WILL PRODUCE 0-6KM SHEAR OF 46KTS WHICH WILL BE SUFFICIENT FOR ROTATING UPDRAFTS...HOWEVER LOW-LEVEL SHEAR IS LIMITED WITH 0-1KM SHEAR OF 15-20KTS. GIVEN DECENT MLCAPE AND HAIL-CAPES...MAIN CONCERN WILL BE LARGE HAIL. WIND FIELD AND SOME MID-LEVEL DRY AIR WILL ALSO PRODUCE A DAMAGING WIND THREAT. WILL HIGHLIGHT THE SEVERE POTENTIAL IN THE HWO. FOR SUNDAY NIGHT AND MONDAY...PLENTY OF WRAP-AROUND MOISTURE AND SOME LOW-LEVEL INSTABILITY TO PRODUCE MOSTLY CLOUDY SKY WITH A CHANCE OF SHOWERS. MAIN DRY FOR TUESDAY AS RIDGING BUILDS IN...BUT ANOTHER SYSTEM IS POSSIBLE BY WEDNESDAY.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 64 82 59 85 / 80 30 10 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 64 81 58 83 / 80 40 10 10 OAK RIDGE, TN 63 81 57 83 / 80 40 10 10 TRI CITIES AIRPORT, TN 60 79 54 80 / 60 50 10 10
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ GM/DH

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