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

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000 FXUS64 KMRX 211910 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 310 PM EDT MON APR 21 2014 .SHORT TERM (TONIGHT THROUGH TUESDAY)...ANOTHER MOSTLY SUNNY DAY ACROSS THE EASTERN TN VALLEY AND SOUTHERN APPALACHIANS WITH TEMPERATURES IN THE MID TO UPPER 70S. DEW POINTS HAD FALLEN INTO THE 30S TO MID 40S. RH VALUES WERE AS LOW AS AROUND 20 TO 25 PERCENT IN SW VA SO FAR ABOUT 5 PERCENT HIGHER THAN SUNDAY. WINDS WERE MOSTLY ABOUT 5 TO 10 MPH OUT OF THE SOUTHWEST OR SOUTH WITH A FEW HIGHER GUSTS. CLOUDS TO THE WEST WERE THICKENING UP AND EXPECT THESE TO MOVE OVER WESTERN SECTIONS THIS EVENING. PRECIPITATION WAS AS CLOSE AS THE LOWER OH VALLEY IN EXTREME WESTERN KY. UPPER LEVEL TROUGH TO THE WEST AND NORTHWEST MOVES SLOWLY EAST OVERNIGHT AND INTO THE FORECAST AREA TUESDAY WITH SHOWERS AND A POSSIBLE THUNDERSTORM. WEAK FRONT TO APPROACH IN THE MORNING AND BE THROUGH ENTIRE AREA BY 00Z WEDNESDAY. RAINFALL AMOUNTS ONLY AROUND ONE QUARTER TO ONE HALF MAINLY DAYTIME HOURS TUESDAY. MODELS HAVE INCREASED RH VALUES BRINGING HIGHER DEW POINTS IN QUICKER THAN WHAT HAS HAPPENED EACH DAY SO WILL KEEP CURRENT DEW POINTS LOW THROUGH ABOUT 00Z TONIGHT. LOWERED DEW POINTS TUESDAY AS WELL. BUMPED LOWS UP A FEW DEGREES WEST TONIGHT WITH INCREASED CLOUDS. HIGHS TUESDAY NEAR GUIDANCE OF UPPER 60S TO MID 70S AS THERE WILL BE LITTLE COLD AIR ADVECTION WITH FRONT UNTIL TUESDAY NIGHT. .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)...MODELS ARE IN GOOD AGREEMENT WITH THE SYNOPTIC-SCALE PATTERN THROUGH THE EXTENDED PERIOD...AND GENERALLY REVEAL A PROGRESSIVE PATTERN THROUGH EARLY NEXT WEEK. AN UPPER-LEVEL RIDGE WILL BUILD ACROSS THE TN RIVER VALLEY TUESDAY NIGHT THROUGH THURSDAY...BRINGING TRANQUIL CONDITIONS AND A WARMING TREND. A WEAK COLD FRONT IS THEN PROGGED TO MOVE ACROSS THE TN RIVER VALLEY LATE THURSDAY NIGHT AND FRIDAY MORNING... BRINGING A CHANCE OF SHOWERS AND TSTORMS. THIS COLD FRONT SHOULD THEN STALL OUT OVER THE DEEP SOUTH ON SATURDAY...AS THE UPPER-LEVEL FLOW BECOMES ZONAL AND PARALLEL TO THE FRONTAL BOUNDARY. THIS FRONTAL BOUNDARY SHOULD THEN MOVE NORTHWARD AS A WARM FRONT ON SUNDAY NIGHT AND MONDAY...AS A DEEP UPPER-LEVEL TROUGH OVER THE WESTERN U.S. FURTHER AMPLIFIES OVER THE SOUTHERN PLAINS. THIS DEEP UPPER TROUGH IS THEN PROGGED TO BRING A STRONG AND SLOW-MOVING LOW PRESSURE SYSTEM ACROSS THE TN RIVER VALLEY ON MONDAY NIGHT AND TUESDAY. THE GFS AND ECMWF MODELS DIFFER SOMEWHAT ON THE EXACT TIMING OF THIS SYSTEM...BUT RIGHT NOW...BOTH MODELS GENERALLY AGREE THAT IT WILL BRING STRONG DYNAMICS OVER THE FORECAST AREA WITH THE POSSIBILITY OF ORGANIZED SEVERE STORMS FOR EARLY NEXT WEEK. AS FOR TEMPS...WILL GENERALLY TREND A LITTLE COOLER THAN THE GFS NUMBERS THROUGHOUT THE EXTENDED PERIOD...WHICH IS IN BETTER AGREEMENT WITH THE ENSEMBLE MEANS. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 60 74 46 73 / 40 70 0 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 58 73 44 71 / 40 70 0 0 OAK RIDGE, TN 59 72 44 71 / 40 70 0 0 TRI CITIES AIRPORT, TN 51 72 39 69 / 30 70 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TD/DMG

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