483
FXUS64 KMRX 171142
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
642 AM EST WED DEC 17 2025
..NEW AVIATION
KEY MESSAGES
UPDATED AT 636 AM EST WED DEC 17 2025
- STRONG MOUNTAIN WINDS, WIDESPREAD SHOWERS, AND ISOLATED THUNDER
IN THE SOUTH ARE EXPECTED ON THURSDAY AND THURSDAY NIGHT.
- AFTERWARDS, DRIER AND COOLER CONDITIONS RETURN.
DISCUSSION
ISSUED AT 1229 AM EST WED DEC 17 2025
A WEAK RIDGE ALOFT REMAINS IN PLACE WHILE SURFACE HIGH PRESSURE
CONTINUES TO SUPPORT DRY WEATHER ACROSS THE SOUTHERN APPALACHIANS.
MID LEVEL STRATUS DECK IS MOVING IN FROM OUR WEST WHICH WILL HELP
KEEP OVERNIGHT TEMPERATURES WARMER THAN WHAT WE'VE EXPERIENCED THE
PAST FEW NIGHTS, WITH LOWS EXPECTED TO DROP NEAR OR JUST BELOW
FREEZING INSTEAD OF THE TEENS. WARM TEMPERATURES WILL REMAIN IN
PLACE WEDNESDAY, A FEW DEGREES WARMER THAN TUESDAY. BY THURSDAY, A
DEEPENING TROUGH WILL DIG ACROSS THE CENTRAL UNITED STATES, DRIVING
WARM AND MOIST AIR ADVECTION INTO THE REGION. TEMPERATURES WILL RISE
ABOVE NORMAL, AND PRECIPITATION CHANCES WILL INCREASE AREAWIDE.
RAINFALL WILL INITIALLY DEVELOP THROUGH ISENTROPIC ASCENT, FOLLOWED
BY A FRONTAL PASSAGE THURSDAY NIGHT.
LOW ASSOCIATED WITH THIS SYSTEM WILL TRACK ACROSS NORTHERN MICHIGAN,
AND FAVORABLE LOW-LEVEL JET ORIENTATION OF 55–65 KTS PER LATEST NAM
GUIDANCE, MOUNTAIN WAVE WINDS ARE EXPECTED ACROSS THE EAST TENNESSEE
MOUNTAINS AND ADJACENT FOOTHILLS. CURRENT PROJECTIONS SUPPORT GUSTS
50 MPH OR MORE. A WIND ADVISORY APPEARS INCREASINGLY LIKELY, WITH
POTENTIAL TO REACH HIGH WIND CRITERIA IN SOME ISOLATED SPOTS AS THE
EVENT APPROACHES.
RAIN WILL BE THE PRIMARY PRECIPITATION TYPE WITH THIS SYSTEM DUE TO
THE WARM TEMPERATURES. A FEW THUNDERSTORMS ARE POSSIBLE ACROSS THE
SOUTHERN TIER, WHERE SOME FORECAST SOUNDINGS INDICATE WEAK ELEVATED
INSTABILITY. DESPITE LIMITED INSTABILITY, THE STRONG LOW-LEVEL JET
COULD ALLOW HEAVIER SHOWERS TO MIX DOWN GUSTS OF 30–40 MPH,
PARTICULARLY AS THE MAIN AXIS FORCING MOVES THROUGH. HOWEVER, THE
RISK OF DAMAGING WINDS REMAINS LOW. 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 CONFINED TO HIGHER ELEVATIONS GIVEN THE ABOVE-NORMAL
TEMPERATURES PRECEDING THE SYSTEM HEATING THE GROUND UP IN ADVANCE.
BEHIND THE FRONT, HIGH PRESSURE WILL RETURN FRIDAY AFTERNOON,
BRINGING DRIER AND COOLER CONDITIONS. THE UPPER-LEVEL FLOW WILL
BECOME QUASI-ZONAL THROUGH THE WEEKEND, THOUGH WEAK DISTURBANCES
COULD PRODUCE OCCASIONAL LIGHT RAIN. NBM GUIDANCE INTRODUCES POPS OF
30% OR LESS FOR THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK.
ANY RAINFALL SHOULD BE LIGHT AND NON-IMPACTFUL, WITH MORE DRY
PERIODS THAN WET. TEMPERATURES WILL REBOUND TO SLIGHTLY ABOVE NORMAL
VALUES OVER THE WEEKEND.
AVIATION
(12Z TAFS)
ISSUED AT 636 AM EST WED DEC 17 2025
VFR THROUGH THE PERIOD, THOUGH A LOW CHANCE FOR MVFR EXISTS AT
KCHA AS LOW LEVEL MOISTURE BEGINS REACHING SATURATION THURSDAY
MORNING. OTHERWISE WINDS ALOFT WILL BE ON THE INCREASE HEADING
INTO THURSDAY MORNING BUT CURRENTLY LOOK TO FALL SHORT OF LLWS
CRITERIA.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 55 39 60 35 / 0 10 80 90
KNOXVILLE MCGHEE TYSON AIRPORT, TN 53 35 61 35 / 10 10 80 100
OAK RIDGE, TN 50 34 59 32 / 10 10 80 100
TRI CITIES AIRPORT, TN 50 33 59 34 / 0 0 50 100
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...99
AVIATION...WELLINGTON
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