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

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000 FXUS64 KMRX 020727 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 327 AM EDT THU APR 2 2015 .SHORT TERM...(TODAY AND TONIGHT)... SHOWER AND THUNDERSTORM ACTIVITY COULD START EARLY TODAY, IN THE FAR SOUTHWESTERN PARTS OF THE CWA, AS A NOSE OF WARM 850 MB TEMPS MOVES INTO THE AREA AHEAD OF A PLUME OF MOISTURE. ANYTHING THAT DOES FORM EARLY IN THE DAY WILL BE SPOTTY AND MOSTLY JUST RAIN SHOWERS, BUT AS THE DAY PROGRESSES COVERAGE SHOULD INCREASE AND WE SHOULD START TO SEE SOME LIGHTNING AS INSTABILITY INCREASES ACROSS THE AREA. BEST CHANCES TO SEE THUNDERSTORMS WILL BE IN THE SOUTHERN HALF OF THE CWA. AT THIS TIME THE SEVERE THREAT LOOKS RELATIVELY MINOR TODAY WITH WEAK INSTABILITY PRESENT ACROSS THE AREA. ALSO OF NOTE TODAY WILL BE THE POTENTIAL FOR BREEZY WINDS, ESPECIALLY IN THE MOUNTAINS. AN 850 MB JET WILL MOVE OVER THE AREA VERY LATE TONIGHT WITH WINDS GENERALLY 40 - 45 KNOTS OVER THE WESTERN HALF OF THE AREA. IF THIS JET MOVES IN A BIT QUICKER, DURING THE DAYTIME HOURS, WE COULD GET BREEZY...ESPECIALLY IN THE HIGHER ELEVATION AREAS. HAVE CURRENTLY HELD OFF ON ISSUING A WIND ADVISORY SINCE IT LOOKS TO BE BORDERLINE AT BEST AT THIS TIME. RAIN CHANCES WILL TAKE A BIT OF A BREAK OVERNIGHT AS SHOWER ACTIVITY DECREASES AHEAD OF THE INCOMING COLD FRONT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY)...FIRST OUTBREAK OF SEVERE WEATHER POSSIBLE LATE FRIDAY AND FRIDAY EVENING. A FAST MOVING SHORT- WAVE AND ASSOCIATED JET WILL MOVE ACROSS THE OHIO VALLEY INTO THE MID-ATLANTIC STATE FRIDAY AND FRIDAY NIGHT. THE TENNESSEE VALLEY WILL BE UNDER THE FAVORED AREA OF DIVERGENCE WITH DIRECT CIRCULATION OF JET ENHANCING FRONTO-GENETIC FORCING ALONG A FRONTAL BOUNDARY. THIS BOUNDARY WILL MOVE ACROSS THE AREA FRIDAY EVENING. AIRMASS AHEAD OF THE FRONT WILL BECOME UNSTABLE...ESPECIALLY OVER MIDDLE TENNESSEE LATE FRIDAY AFTERNOON. A SQUALL LINE OF THUNDERSTORMS WILL FORM OVER MIDDLE TENNESSEE THEN QUICKLY MOVE EAST INTO THE PLATEAU IN THE EVENING...THEN ACROSS THE REST OF THE REGION SOON AFTER MIDNIGHT. DUE TO STRONG LOW-LEVEL JET (850MB WINDS OF 50- 55KTS)...MAIN CONCERN WILL BE DAMAGING WINDS. FORECAST SOUNDINGS DO SHOW SOME SHEAR...BUT MAINLY SPEED SHEAR. SPC HAS PLACED THE WESTERN HALF OF THE AREA UNDER THE SLIGHT RISK WITH ENHANCED AREA OVER MIDDLE TENNESSEE. WILL INCLUDE RISK OF SEVERE WEATHER WITHIN THE HWO. RIDGE OF HIGH PRESSURE AND DRY NORTHWEST FLOW FOR SATURDAY THROUGH SUNDAY. SURFACE RIDGE MOVES EAST OF THE SOUTHERN APPALACHIANS SUNDAY WITH SOUTHERLY WINDS PULLING MOISTURE BACK INTO THE AREA. FAST WESTERLY FLOW WILL PULL A SERIES OF SHORT-WAVES ACROSS THE AREA INCREASING SOUTHERLY LOW-LEVEL JET AND ENHANCING ISENTROPIC LIFT. SHOWERS AND THUNDERSTORMS CHANCES INCREASE EARLY/MID NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 72 59 75 46 / 50 20 50 60 KNOXVILLE MCGHEE TYSON AIRPORT, TN 71 58 73 43 / 40 30 60 70 OAK RIDGE, TN 70 58 73 43 / 40 30 70 70 TRI CITIES AIRPORT, TN 73 55 70 40 / 20 40 70 80 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ ABM/DH

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