703
FXUS64 KMRX 162315
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
615 PM EST MON DEC 16 2024
..NEW AVIATION
SHORT TERM
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 245 PM EST MON DEC 16 2024
KEY MESSAGES:
1. CLOUDS, RAIN, AND FOG THROUGH TUESDAY.
2. ABOVE NORMAL TEMPS TONIGHT AND TUESDAY. NEAR RECORD HIGH-MINIMUM
TEMPERATURES OVERNIGHT.
DISCUSSION:
UNFORTUNATELY, LOW CLOUDS, FOG, AND RAIN WILL CONTINUE TO REMAIN IN
PLACE THROUGH TUESDAY. A COLD FRONT IS CURRENTLY APPROACHING FROM
THE NORTHWEST AND WILL MOVE INTO OUR AREA OVERNIGHT. RAIN WILL MOVE
INTO THE AREA THIS EVENING AND WILL PERSISTS THROUGH TUESDAY. DUE TO
VERY MINOR, ELEVATED, INSTABILITY AN ISOLATED STORM IS POSSIBLE BUT
LOW PROBABILITY. IF AN ISOLATED STORM OCCURS, THE BEST CHANCES WOULD
BE ACROSS THE CENTRAL AND SOUTHERN TN VALLEY. NO IMPACTS EXPECTED.
THE BULK OF THE PRECIP WILL EXIT BY TUESDAY MORNING. OVERNIGHT
PRECIP AMOUNTS WILL GENERALLY RANGE FROM 0.1 TO 0.3 INCHES FOR MOST
AREAS. HOWEVER, THE FRONT LOOKS LIKE IT WILL STALL OVER THE AREA.
THIS WILL KEEP LIGHT SHOWERS/DRIZZLE IN PLACE THROUGH THE DAY.
RAINFALL AMOUNTS FROM A FEW HUNDREDTHS OF AN INCH UP TO 0.1 INCHES
ARE EXPECTED.
DRIER AIR TRIES TO MOVE INTO OUR NORTHERN MOST AREAS LATE TUESDAY
AFTERNOON. SO PERHAPS A PEAK OF SUNSHINE FOR AREAS ALONG THE TN/KY
BORDER AND OUR SOUTHWEST VA COUNTIES. TEMPERATURES REMAIN MILD
THROUGH TUESDAY. NEAR RECORD HIGH-MINIMUM TEMPERATURES ARE EXPECTED
TONIGHT WITH TEMPS IN THE LOW TO MID 50S.
LONG TERM
(TUESDAY NIGHT THROUGH NEXT MONDAY)
ISSUED AT 245 PM EST MON DEC 16 2024
KEY MESSAGES:
1. WEDNESDAY WILL BE THE LAST DAY WITH WIDESPREAD BENEFICIAL
RAINFALL CHANCES THROUGHOUT THE LONG TERM PERIOD. BREEZY WINDS ARE
ALSO EXPECTED DURING THE AFTERNOON.
2. ABOVE NORMAL TEMPERATURES WEDNESDAY WILL GRADUALLY TRANSITION TO
MUCH COLDER TEMPERATURES LATE WEEK AND CONTINUE INTO THE WEEKEND.
DISCUSSION:
BY TUESDAY NIGHT INTO WEDNESDAY MORNING A DEEP POSITIVELY TILTED
TROUGH WILL BEGIN TO SWING TOWARDS THE MISSISSIPPI RIVER VALLEY AS
ISENTROPIC ASCENT INCREASES LOCALLY. MODEL GUIDANCE STILL VARIES
WITH THE OVERALL EFFICIENCY OF THIS UPGLIDE, WITH MORE COARSE MODELS
LINGERING RAIN CHANCES DURING THE OVERNIGHT HOURS WHILE THE NAM
REMAINS DRY BEFORE AN APPROACHING SURFACE FRONT INTO THE DAYTIME
HOURS. NONETHELESS, CLOUDS WILL PERSIST IN THE OVERNIGHT WITH SOME
LINGERING LOW (20-30%) POP CHANCES. NEAR RECORD HIGH MINIMUM
TEMPERATURES ARE EXPECTED. THE CHANCE FOR RAIN AND BREEZY CONDITIONS
WILL BECOME MORE WIDESPREAD AS BOTH FRONTOGENESIS & CYCLOGENESIS
INCREASE INTO THE DAYLIGHT HOURS. STRONGEST GUSTS OF 30-40MPH WILL
OCCUR IN HIGHER ELEVATIONS OF THE EAST TENNESSEE MOUNTAINS AND
SOUTHWEST VIRGINIA AS A ~45KT SOUTHWEST LLJ ALSO SWINGS THROUGH THE
REGION. WEAK INSTABILITY REMAINS IN MODEL DERIVED SOUNDINGS SO WHILE
THUNDER CHANCES ARE NON-ZERO, THEY REMAIN LOW.
TEMPERATURES WILL TREND COOLER AS SURFACE FLOW SHIFTS TO THE
NORTHWEST THURSDAY. AN IMPULSE WILL REINFORCE TROUGHING AND DEEP
NORTHWESTERLY FLOW INTO THE WEEKEND. THIS MAY BRING SOME SNOW NWFS
SHOWERS DEPENDING ON MOISTURE AVAILABILITY BUT PLENTY OF UNCERTAINTY
STILL EXISTS AT THIS TIME. LATEST ENSEMBLE PROBABILITIES OF SNOW
ACCUMULATION GTE 1" ARE AROUND 20-30%. OVERALL, A MOSTLY DRY WEEKEND
WITH BELOW NORMAL TEMPERATURES CAN BE EXPECTED.
AVIATION
(00Z TAFS)
ISSUED AT 613 PM EST MON DEC 16 2024
DIFFICULT FORECAST WITH SEVERAL PERIODS OF ON AND OFF SHOWERS FOR
THE NEXT 12-18 HOURS, AND CEILINGS/VISIBILITIES LIKELY TO BOUNCE
BETWEEN MVFR AND IFR FOR THE ENTIRE PERIOD. INITIAL ROUND OF RAIN
IS NOT BEING HANDLED WELL BY MODELS, SO HAVE GONE PESSIMISTIC AND
BROUGHT CATEGORIES DOWN A BIT MORE THAN GUIDANCE SUGGESTS. ONCE
THIS INITIAL ROUND GETS OUT THE LOW CEILINGS WILL REMAIN AND
PERIODS OF LIGHT RAIN WILL OCCUR THROUGHOUT THE ENTIRE OVERNIGHT
PERIOD.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 54 63 55 67 / 90 50 40 80
KNOXVILLE MCGHEE TYSON AIRPORT, TN 55 62 55 65 / 90 40 50 80
OAK RIDGE, TN 54 61 53 63 / 90 30 50 80
TRI CITIES AIRPORT, TN 51 60 50 63 / 80 30 40 80
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...
LONG TERM....KRS
AVIATION...
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