textproduct: Morristown

KEY MESSAGES

Updated at 721 AM EDT Sat Aug 1 2026

- Showers and storms will move in today and continue tonight into Sunday. A few storms may become strong to severe, especially over the Plateau and the southern Tennessee valley late Saturday into Saturday night. Localized flooding will also be possible.

- Scattered showers and storms can be expected each day Monday through Friday, especially during the afternoon hours.

DISCUSSION

Issued at 129 AM EDT Sat Aug 1 2026

Model run to run agreement is still poor overall, so the details even in the short term are not as certain as would be preferred. However, the basic pattern is not much in doubt with an upper low moving out of the mid Mississippi Valley and into the Ohio River Valley/southern Great Lakes region through Sunday. A cold front will approach us from the west and eventually move into/through our area Saturday night and/or Sunday. The details of how strong and the exact track of both the low pressure system and how quickly the front will move into and through our area have been handled very inconsistently by the models. However, there is high confidence that showers and thunderstorms will move into our area later tonight and this morning as moisture surges in with the increasing southerly flow and divergence aloft ahead of the upper trough. This thunderstorm activity is expected to be sub-severe, as CAPE will be modest and the convection likely elevated at first.

Clouds and convection during the day Saturday will impact how much instability develops, but it currently looks like at least moderate MLCAPE of 1000 to 1500 J/kg will develop over western areas during the afternoon. By late today/this evening the front will be moving into middle TN, and the CAMS generally show additional convection firing ahead of the front and moving east toward our area. Models have around 20 to 30 kts of effective shear which given at least moderate instability would support organization of the convection and the potential for some strong to severe storms with damaging winds the primary threat. The best low level shear looks to stay to our north and northwest, but there is sufficient low level shear and clockwise curvature of the hodograph that a tornado cannot be ruled out especially if the CAPE and shear potential is maximized. The severe potential should be highest for our Plateau and southern valley counties where the convection will arrive first and surface CAPE will have less time to decrease from loss of solar heating. The low level jet will be out of the south and southeast across the mountains Saturday and Saturday night, with downslope flow into the valley. In fact, we will likely see gusty winds in the usual higher mountain elevation and foothill areas with some mountain wave enhancement of the winds, although it generally should stay sub-wind advisory level. Given this downslope flow as well as the later arrival of the convection in our central and northern/eastern areas, it is not surprising that the CAMS quickly weaken the convection as it progresses further east across our area.

In addition to the severe threat, given the abundant moisture with PWAT values near or exceeding 2 inches for Saturday into Saturday night very heavy rainfall and localized flooding will also be possible, especially across the Plateau and southern portions of our area.

Depending on how quickly the front clears our area, a marginal severe storm threat may continue into Sunday over our northeast counties ahead of the boundary where significant effective shear and instability will be lingering ahead of the front. Behind the front, any showers and storms should be more isolated to scattered and weaker Sunday.

The later periods continue to feature significant chances for showers and storms each day Monday through Friday but with the highest chances early in the week in response to a meandering weak upper low that most models leave behind over the region. Models still disagree on placement and movement of the upper low, and some, while in the minority, would suggest a quicker return to drier and warmer conditions. We will have to see as we get closer.

AVIATION

(12Z TAFS) Issued at 721 AM EDT Sat Aug 1 2026

Multiple rounds of showers and storms will move through the region starting this morning. The best chance for thunder will be in the late afternoon and evening hours. TRI will see less activity. The highest confidence of rain and thunder will be in the evening hours at all terminals. MVFR CIGs are briefly possible this morning and likely late tonight. Southerly winds will be gusty at times.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 88 72 86 70 / 90 90 50 10 Knoxville McGhee Tyson Airport, TN 88 72 86 70 / 80 80 60 40 Oak Ridge, TN 86 71 85 69 / 90 90 70 30 Tri Cities Airport, TN 84 69 85 67 / 40 70 90 60

MRX WATCHES/WARNINGS/ADVISORIES

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