464
FXUS64 KMRX 181143
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
643 AM EST THU DEC 18 2025
..NEW AVIATION
KEY MESSAGES
UPDATED AT 635 AM EST THU DEC 18 2025
- WIND ADVISORY FOR STRONG MOUNTAIN WINDS; MEANWHILE WIDESPREAD
SHOWERS, AND ISOLATED THUNDER IN THE SOUTH ARE EXPECTED THIS
AFTERNOON INTO EARLY FRIDAY MORNING.
- COLDER TEMPERATURES BEHIND A FRONT ON FRIDAY, BUT REBOUND
QUICKLY OVER THE WEEKEND AND REMAIN MILD NEXT WEEK WITH MAINLY
DRY CONDITIONS.
DISCUSSION
ISSUED AT 1232 AM EST THU DEC 18 2025
LITTLE CHANGE FROM THE PREVIOUS FORECAST. A DEEP UPPER TROUGH WILL
SWING THROUGH THE AREA IN THE SHORT TERM, YIELDING STRONG MOUNTAIN
WINDS, SHOWERS, AND A FEW RUMBLES OF THUNDER.
WINDS:
THE 850MB JET BEGINS TO RAMP UP BETWEEN 09Z AND 12Z THIS MORNING.
12Z IS WHEN A WIND ADVISORY GOES INTO EFFECT FOR THE EAST TN
MOUNTAIN ZONES. THIS WILL BE A PROLONGED EVENT AS THE LLJ REMAINS
ELEVATED THROUGH FRIDAY MORNING, UNTIL THE FRONTAL PASSAGE. THE WIND
ADVISORY IS SET TO EXPIRE 09Z FRIDAY. HREF PROBS SHOWS HIGH
CONFIDENCE IN GUSTS UP TO 40 MPH WITHIN THE ADVISORY AREA. THOSE
PROBABILITIES WANE AS YOU LOOK AT GUST PROBS FOR 50 MPH AND
GREATER. REFS ISN'T AS AGGRESSIVE WITH THE WINDS OVERALL, WITH
MORE MUTED CONDITIONS OVERALL AND LESSER PROBABILITIES OF CRITERIA
OVER THE PLATEAU. THERE IS AN ISOLATED AREA FOR GUSTS UP TO 60
MPH, WITH MODERATELY HIGH PROBS, ACROSS AREAS SUCH AS COVE
MOUNTAIN. SO WHILE A FEW ISOLATED LOCATIONS WILL LIKELY SEE HIGH
WIND WARNING CRITERIA, THE MAJORITY OF THE MOUNTAINS WILL ONLY SEE
ADVISORY LEVEL GUSTS. OPTING NOT TO ISSUE A WIND ADVISORY OVER THE
NORTHERN PLATEAU COUNTIES, NOT CONVINCED THE ATMOSPHERE WILL MIX
DOWN ADVISORY STRENGTH GUSTS GIVEN POOR LAPSE RATES IN THE LOWEST
1 KM OF ATMOSPHERE, AND SO WILL SIDE WITH THE REFS MEAN DEPICTION.
NAM SOUNDINGS SHOW THE LOW-LEVEL INVERSION ERODING LATTER THIS
AFTERNOON WHEN SHOWERS ARRIVE. THIS IS WHEN VALLEY LOCATIONS WILL
LIKELY BEGIN TO SEE SOME 20 TO 30 MPH GUSTS. TOWARD THIS EVENING, A
FEW THUNDERSTORMS ARE ALSO POSSIBLE ACROSS THE SOUTHERN TIER BETWEEN
00-06Z. THIS IS WHEN THERE IS AN EVEN GREATER CHANCE FOR VALLEY
LOCATIONS TO SEE SOME HIGHER GUSTS. THIS IS DUE TO THESE HEAVIER
SHOWERS HAVING BETTER CHANCES TO TRANSPORT HIGHER WINDS ALOFT DOWN
TO THE SURFACE. WIND GUSTS FROM 30 TO 40 MPH ARE POSSIBLE. THIS IS
SUPPORTED BY THE WIDESPREAD 80 TO 90% HREF PROBS FOR GUSTS OVER 20
MPH IN MANY VALLEY LOCATIONS THIS AFTERNOON, AND THEN 80 TO 90%
PROBS THIS EVENING FOR GUSTS OVER 35 MPH.
RAIN:
PRECIP ARRIVES FIRST ACROSS THE SOUTHERN TN VALLEY THIS AFTERNOON,
THEN SPREADING NORTHEAST THROUGH THIS EVENING. FAVORED DOWNSLOPING
AREAS ALONG THE FOOTHILLS OF THE EAST TN MOUNTAINS AND INTO THE
VALLEY WILL LIKELY REMAIN PRECIP FREE UNTIL LATE TONIGHT WITH ANY
MEANING PRECIP NOT OCCURRING UNTIL EARLY FRIDAY MORNING. NBM PRECIP
LOOKS OVERDONE ACROSS THESE DOWNSLOPE AREAS SO WILL TREND QPF
AMOUNTS DOWNWARD.
ON THE BACKSIDE OF THE SYSTEM EARLY FRIDAY MORNING, LIGHT SNOW MAY
OCCUR IF COLD AIR ADVECTION AND NORTHWEST FLOW ALIGN WITH LINGERING
MOISTURE. ANY ACCUMULATIONS WOULD LIKELY BE VERY LIGHT GIVEN THE
SHORT DURATION OF OVERLAP BETWEEN THE EXITING MOISTURE AND THE
BUILDING COLD AIR.
REST OF THE FORECAST:
COLDER TEMPERATURES FOLLOW THE STRONG COLD FRONT ON FRIDAY, WITH
HIGHS IN THE 40S. HIGHS REBOUND BACK TO THE 50S FOR SATURDAY AND
SUNDAY. A WEAK DISTURBANCE MAY BRING SOME LIGHT RAIN SATURDAY NIGHT
INTO SUNDAY BUT LOW PROBABILITIES. HIGH TEMPS SHOULD BE MOSTLY IN
THE 50S FOR NEXT WEEK. THERE ARE SOME MORE WEAK DISTURBANCES
SHOWN IN THE MODELS THAT BRING LOW RAIN CHANCES NEXT WEEK, MAINLY
TUESDAY-WEDNESDAY, BUT THESE APPEAR TO HAVE LITTLE TO NO IMPACTS,
IF THEY HAPPEN AT ALL.
AVIATION
(12Z TAFS)
ISSUED AT 635 AM EST THU DEC 18 2025
STRONG FLOW ALOFT WITH POOR LAPSE RATES IS FORECAST TO LEAD TO AN
EXTENDED PERIOD OF LLWS TODAY. SHOULD WINDS BE ABLE TO MIX DOWN
TO THE SURFACE, WIND SHEAR THREAT WILL BE LESSENED. CIGS WILL
GRADUALLY DETERIORATE TODAY, EXCEPT FOR KTRI. TONIGHT A THIN LINE
OF MODERATE TO BRIEFLY HEAVY RAIN WILL CROSS FROM WEST TO EAST IN
ASSOCIATION WITH THE COLD FRONT. IFR VIS DURING THIS LINE IS
POSSIBLE. THIS BOUT OF RAIN WILL ALSO COINCIDE WITH THE END OF
WIND SHEAR, AS STRONG MIXING OCCURS ON THE BACKSIDE OF FROPA. KTRI
WILL DETERIORATE TO MVFR DURING THIS TIME AS WELL, LATE IN THE
PERIOD.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 60 36 50 29 / 90 90 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 61 36 45 27 / 60 100 10 0
OAK RIDGE, TN 58 33 45 26 / 70 90 0 0
TRI CITIES AIRPORT, TN 59 36 42 25 / 50 90 10 0
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...WIND ADVISORY UNTIL 4 AM EST FRIDAY FOR BLOUNT SMOKY MOUNTAINS-
COCKE SMOKY MOUNTAINS-JOHNSON-SEVIER SMOKY MOUNTAINS-
SOUTHEAST CARTER-SOUTHEAST GREENE-SOUTHEAST MONROE-UNICOI.
VA...NONE.
DISCUSSION...99
AVIATION...WELLINGTON
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