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

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000 FXUS64 KMRX 241915 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 312 PM EDT THU APR 24 2014 .SHORT TERM (TONIGHT AND FRIDAY)...
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STRENGTHENING SHORT WAVE WILL MOVE EAST ACROSS TN VALLEY TONIGHT. DEEPENING SURFACE LOW MOVES NE INTO THE W OH RIVER VALLEY BY FRIDAY MORNING. AIRMASS WILL MOISTEN UP OVERNIGHT WITH INCREASED SOUTHWESTERLY LOW LEVEL FLOW. INSTABILITY MEAGER BUT GOOD LIFT IN ADVANCE OF THE APPROACHING SHORT WAVE WILL RESULT IN CONVECTIVE DEVELOPMENT IN ADVANCE OF APPROACHING COLD FRONT. BEST CHANCE FOR STRONG CONVECTION AND ISOLATED THUNDERSTORMS WILL BE BETWEEN 25/09-25-15Z ACROSS MRX CWA. UPPER TROUGH AXIS...COLD FRONT...WIND SHIFT...WILL MOVE THROUGH SHORTLY AFTER 25/18Z. CONVECTION WILL TAPER OFF IN THE AFTERNOON HOURS. WARM TONIGHT WITH NEAR NORMAL TEMPERATURES ON FRIDAY WITH WEAK COLD OR NEUTRAL AIR ADVECTION BEHIND THE FRONT LATE. .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...THIS PERIOD WILL START OUT DRY AND QUIET...BUT WILL TURN MESSY FOR ITS SECOND HALF. AT THE BEGINNING OF THIS PERIOD ON FRIDAY NIGHT...SURFACE HIGH PRESSURE IS BUILDING INTO THE AREA BEHIND A WEAK COLD FRONT. SATURDAY LOOKS BEAUTIFUL...WITH SUNDAY BEGINING THE RETURN FLOW FROM THE GULF BRINGING WARMER AIR AND AND THE UPPER RIDGE OVERHEAD SHOULD MAKE FOR A WARM DAY. THE AFOREMENTIONED MESSINESS DEALS WITH THE CUT-OFF LOW THAT IS PROGGED TO HANG IN THE UPPER MISS VALLEY AND GREAT LAKES FOR SEVERAL DAYS...WITH ITS ASSOCIATED TROUGH HANGING IN OUR AREA. WITH A CUT- OFF LOW...TIMING OF SYSTEMS MOVING THROUGH COULD BE AN ADVENTURE. ON MONDAY THE FIRST WAVE WILL BE MOVING IN...BUT THE SYSTEM WILL BE GETTING STRUNG OUT AS THE ANCHORING SURFACE LOW STAYS IN THE PLAINS AND ANY STORMS MOVING INTO OUR AREA FROM WEST/MIDDLE TN GET FARTHER AND FARTHER AWAY FROM THE DYNAMICS. TUESDAY IS STARTING TO LOOK MORE AND MORE INTERESTING NOW...AS THE SYSTEM KICKS EAST...THE DYNAMICS WILL BE HEADING THIS WAY AS WELL...BUT MODELS LOOKING LIKE THEY WANT A LOT OF PRECIP WELL AHEAD OF THE FRONT AND THE DYNAMICS...SO IT MIGHT BE DIFFICULT TO GET GOOD HEATING DURING THE DAY...ALSO LOOKS LIKE TIMING MIGHT BE BETTER FOR WEST/MIDDLE TN DURING MAX HEATING AGAIN ON TUESDAY...AND THEN THE STORMS WOULD MOVE IN HERE TUESDAY EVENING OR NIGHT. AT ANY RATE...FOR NOW OUR SEVERE THREATS LOOK PRETTY LIMITED THIS FAR EAST. FOR PRECIP AMOUNTS...AIR MASS GETS HIGH MOISTURE WITH PRECIPITABLE WATER WITH VALUES >= 1.2 INCHES FROM 06Z TUE THROUGH 06Z WED. LOOKING LIKE WE MAY NEED TO KEEP AN EYE ON QPF MORE THAN SEVERE PARAMETERS AT THIS POINT. WPC QPF FORECAST HAS HEAVIEST AXIS JUST SOUTH OF OUR CWA...WITH A "HOLE" IN THE 7 DAY QPF OVER MUCH OF MIDDLE AND EAST TN...BUT ENSEMBLES PROBABLILITIES HINT THAT THE AXIS COULD MOVE MORE DIRECTLY OVER OUR AREA. EVEN THE AXIS AS IS COULD POSE SOME PROBLEMS IN OUR MORE- PRONE HYDRO STREAMS AT SOUTH CHICAMAUGA CREEK NEAR KCHA AND THE RIVER STRETCHES NEAR NEWPORT. THERE IS LOW CONFIDENCE ON TIMING DUE TO CUT-OFF LOW`S FICKLE MOVEMENT...WE WILL NEED TO KEEP WATCHING FOR CHANGES IN TIMING AND ALIGNMENT OF PARAMETERS AS TO WHETHER THIS SCENARIO HOLDS. BY WEDNESDAY...LOOKS LIKE GOOD AGREEMENT THAT THE COLD FRONT WILL BE PAST US AND COOLER AIR WILL BY MOVING IN...BUT THE UPPER LOW IS FORECAST TO HANG IN THE GREAT LAKES AND SEND MOISTURE AND LIFT OVER US IN THE NORTHWEST FLOW. LOOKS LIKE WE MIGHT HAVE A DRY SLOT MOVE INTO THE AREA BY AROUND THURSDAY...BUT TIMING A DRY SLOT THIS FAR OUT IN THIS SCENARIO IS RISKY...SO WILL NEED TO KEEP SOME LOW POPS IN. FOR TEMPERATURES...WITH THE ABOVE SCENARIO IN HAND...WILL GO LOWER WITH THE TUESDAY MAX TEMP ACROSS THE AREA...ESPECIALLY SOUTH WHERE THERE SHOULD BE NO SUN ALL DAY.
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&& .PRELIMINARY POINT TEMPS/POPS...
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CHATTANOOGA AIRPORT, TN 58 74 45 82 / 70 20 10 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 56 73 46 80 / 80 80 10 0 OAK RIDGE, TN 56 73 45 80 / 80 40 10 0 TRI CITIES AIRPORT, TN 50 72 42 77 / 70 80 10 0
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SON/GM

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