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

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000 FXUS64 KMRX 291852 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 252 PM EDT FRI APR 29 2016 .SHORT TERM (TONIGHT AND SATURDAY)...SHOWERS AND THUNDERSTORMS OVER N MS AND W TN WILL SLOWLY MOVE EAST OVERNIGHT AND WEAKEN. IF IT HOLDS TOGETHER THERE MAY BE A FEW LIGHT SHOWERS THAT BEGIN TO MOVE ACROSS WESTERN AREAS OF THE FORECAST AREA BY SUNRISE. ONE CHALLENGE TO THE FORECAST IS THE LOCATION AND NORTHWARD MOVEMENT OF THE WARM FRONT THAT BEGINS MOVING OUT OF NORTH GEORGIA/ALABAMA SOMETIME EARLY SATURDAY. THE GFS IS MORE AGGRESSIVE THAN THE NAM IN REGARDS TO PRECIPITATION COVERAGE. THE NAM TENDS TO HANDLE SMALLER SCALE FEATURES BETTER AND WHILE BOTH MODELS AGREE THAT AFTERNOON THUNDERSTORMS ARE A GOOD BET...THE FIRST HALF OF THE DAY SATURDAY LOOKS LIKE SHOWERS WITH A FEW POCKETS OF THUNDERSTORMS POSSIBLE...ALBEIT CONFIDENCE IS RATHER LOW UNTIL LATE MORNING (AFTER 9AM EDT). THE MAIN SHORTWAVE PROVIDING UPPER SUPPORT FOR THE STORMS IS NOT EXPECTED UNTIL AFTERNOON. THAT WILL BE THE BEST TIME FOR MOST AREAS TO EXPERIENCE MUCH NEEDED RAINFALL IN THE FORM OF SHOWERS AND THUNDERSTORMS. A FEW OF THE STORMS THAT DEVELOP WILL APPROACH SEVERE LIMITS PARTICULARLY ALONG THE FRONTAL BOUNDARY. THE SPC HAS A MARGINAL RISK HIGHLIGHTED ACROSS SW NC. RAINFALL AMOUNTS THROUGH TOMORROW AFTERNOON WILL GENERALLY BE LESS THAN ONE HALF INCH WITH LOCALLY HIGHER AMOUNTS POSSIBLE. .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... AS WE MOVE INTO THE EVENING/OVERNIGHT HOURS WITH THE FRONT RETREATING BACK NORTHWARD THERE IS A CHANCE FOR SOME SHOWER AND THUNDERSTORM ACTIVITY. LIKELY MOST OF THE AREA WOULD MOSTLY SHOWERS, BUT IN OUR FAR WESTERN NORTH CAROLINA COUNTIES WE COULD SEE ENOUGH MOISTURE RETURN COMBINE WITH SOME LIMITED INSTABILITY TO CAUSE SOME STRONG STORMS. MORE WIDESPREAD PRECIPITATION ACTIVITY WILL SWEEP THROUGH FROM MIDDLE TENNESSEE EARLY SUNDAY MORNING. AFTER THIS EARLY MORNING ACTIVITY THERE WILL LIKELY BE ANOTHER ROUND OF THUNDERSTORMS SUNDAY EVENING. MODELS SOUNDINGS ARE STRUGGLING TO COME INTO AGREEMENT WITH POTENTIAL SEVERE INGREDIENTS OVER OUR AREA IN ADDITION TO THE LOCATION OF A FRONTAL BOUNDARY WHICH COULD BE THE FOCUS FOR THE STRONGER STORMS. AT THIS TIME IT LOOKS LIKE THERE WILL BE ENOUGH CAPE FOR LARGE HAIL SUNDAY EVENING TO BE A THREAT, BUT AS USUAL OUT HERE STRONG STRAIGHTLINE WINDS CAN ALSO NOT BE RULED OUT. AS WE HEAD INTO THE WORK WEEK MODELS STILL CONTINUE TO HANDLE WHAT WILL HAPPEN WITH OUR NEXT ROUND OF SYSTEMS. GFS IS STILL FURTHER SOUTH AND EAST WITH THE FRONT AND KEEPING MOST OF THE PRECIP EAST OF US UNTIL A STRONG UPPER LEVEL LOW MOVES OVER US TUESDAY INTO WEDNESDAY. ON THE OTHER HAND THE ECMWF HANGS THE FRONT FURTHER BACK LEADING TO PROLONGED RAINFALL EARLY IN THE WEAK, BUT IS MUCH WEAKER WITH A TROUGH MOVING OUT OF THE CENTRAL PLAINS. ANOTHER FRONT WILL THEN MOVE IN FROM THE NORTH IN THE SECOND HALF OF THE WORK WEEK, BUT AGAIN MODELS ARE STRUGGLING WITH THE MOISTURE AVAILABLE WITH THIS SYSTEM AND HOW TO HANDLE A DEVELOPING LOW PRESSURE BEHIND IT, BUT IT LOOKS LIKE THE END OF THE 7-DAY FORECAST WILL END ON A COLD NOTE. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 62 81 65 82 / 20 60 70 70 KNOXVILLE MCGHEE TYSON AIRPORT, TN 61 80 63 81 / 10 70 60 70 OAK RIDGE, TN 61 79 63 81 / 20 70 70 70 TRI CITIES AIRPORT, TN 56 79 58 80 / 20 70 60 70 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ AC/SR

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