textproduct: Morristown

KEY MESSAGES

Updated at 610 PM EST Tue Dec 16 2025

- Dry and cool conditions are expected today with very low RH.

- A warming trend will continue through the week with a system impacting the area Thursday. Strong mountain winds, widespread showers, and isolated thunder in the south are expected.

- Afterwards, drier and cooler conditions return.

DISCUSSION

Issued at 1242 PM EST Tue Dec 16 2025

We remain seated underneath weak riding aloft while surface high pressure continues to influence dry conditions across the southern Appalachians. Latest satellite and surface observations depict a low stratus deck advecting through the Tennessee Valley into the Ohio River Valley. Locations along or north of I-40 may see a period of mostly cloudy skies as this deck lifts north and east. A slight warming trend will persist into the mid-week as seasonal temperatures are expected Wednesday.

By Thursday, an amplified trough will dig through the central CONUS, greatly enhancing strong warm and moist air advection into the region. Temperatures will climb above normal and precipitation chances will increase area-wide with an initial period of isentropic ascent followed by a frontal passage Thursday night.

While the parent low will be located over northern Michigan, CAD will enhance the pressure gradient locally. Combined with favorable LLJ direction around 55-65kts per latest NAM solutions, mountain wave enhancement winds are expected in the East Tennessee mountains and adjacent foothills. Will up the wording to 55mph in the HWO but do believe this upper threshold could increase as we start to see high-resolution models come into play. The eventual need for a Wind Advisory seems likely as we get closer to the event, with potential for this to trend into High Wind criteria. Will continue to monitor closely.

Regarding shower and storm chances, this system will feature predominant rain, though, a few rumbles of thunder my occur in the southern tier where NAMBufr soundings depict very minor elevated instability no greater than 200J/kg. With the strong low-level jet, the heaviest showers could still help transport gusty winds between 30-40mph to the surface at times. Particularly as the main axis of frontogentic forcing swings through the region as depicted by latest RRFS guidance. Overall, a lack of instability is expected to keep the threat of damaging winds very low. Some light snow may be possible on the backside of the system early Friday morning. This will be conditional on the alignment of cold air advection & northwest flow with lingering moisture availability. The above normal temperatures in place ahead of the system suggest any light accumulations would likely be limited to higher terrain.

High pressure builds in post-frontal passage, with drier and relatively cooler conditions Friday afternoon. While the upper-level pattern will be quasi-zonal through the weekend, weak impulses could result in some light rain at times. As a result, NBM does introduce 30% or lower PoPs for the latter half the weekend into the new work week. Uncertainties aside, this would more than likely be non- impactful rain and more time spent dry than not. Temperatures return to slightly above normal values for the weekend as well.

AVIATION

(00Z TAFS) Issued at 610 PM EST Tue Dec 16 2025

Low level stratus deck is continuing to work it's way north through the region and will impact KTRI for the first couple of hours. Afterwards expect VFR conditions for the remaining 24 hours at all sites.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 32 55 41 60 / 0 10 10 90 Knoxville McGhee Tyson Airport, TN 30 53 37 61 / 0 10 10 80 Oak Ridge, TN 31 50 36 58 / 0 10 10 80 Tri Cities Airport, TN 28 49 35 59 / 0 10 0 50

MRX WATCHES/WARNINGS/ADVISORIES

NC...NONE. TN...NONE. VA...NONE.