textproduct: Morristown

KEY MESSAGES

Updated at 640 AM EDT Wed Jul 22 2026

- Multiple rounds of showers and storms will affect the area tonight into at least Wednesday night as a slow moving cold front approaches from the northwest and moves through the forecast area.

- Very heavy rainfall will be possible with a threat of flash flooding tonight through Wednesday night, with the primary threat mainly northern half or two thirds of the area tonight into Wednesday before shifting southward late Wednesday.

- Below normal high temperatures can be expected Thursday through Saturday, then temperatures will not be far from normal for the remainder of the period.

DISCUSSION

Issued at 111 AM EDT Wed Jul 22 2026

Upper troughing over the eastern CONUS, and embedded shortwaves moving through the Ohio valley, will help to push a cold front through our area over the next 24 hours or so. It's currently situated well to our northwest, but it will be approaching from the northwest after daybreak tomorrow, finally pushing in the southern parts of the CWA or perhaps completely south of the area by late Wednesday night. The main concern with this front will be the potential for training storms that develop during the pre-dawn hours later tonight and the associated flooding risks that occur, and then whether or not additional convection fires along the front before it moves out of our area Wednesday night for a flood risk in our southern CWA.

For the pre-dawn hours overnight, several runs of CAM guidance this afternoon and evening have been pointing towards development of showers and thunderstorms across the northern TN valley and into our VA counties as forcing ahead of the cold front coincide with confluent and front-parallel H85 flow move into that region. This would support training convection along/ahead of the front, yielding the potential for high rainfall amounts. HREF probabilities show 30 to 40 percent odds for 6hr rainfall amounts to exceed 2" while several HRRR runs this evening have shown explicit deterministic rainfall amounts in the 3-5" range somewhere over the northern TN valley and northern East Tennessee mountains. All of this yields confidence that there is still a risk of flash flooding tonight. Believe the flash flood watch in place adequately covers the risk area.

There is some concern about whether an additional watch, or perhaps an expansion of the current watch, will be necessary for Wednesday night. As the front slowly shifts south through the region tomorrow, redevelopment of convection along the front is likely. Again, storm motions will be parallel to the front, giving continued risk of training storms and locally high rainfall amounts. At this time, there remains enough uncertainty about the location of the front when that next round of storms fires in earnest. It could be in our far southern areas, or it could be just south of our forecast area. It's even possible that the threat affects our southern tier counties and lingers into Thursday if the front struggles to fully push south of our CWA. For these reasons, I'd prefer to hold off on expanding the current watch or issuing a new one to avoid confusion and allow details to become a little more clear.

The remainder of the forecast has the basic pattern of upper ridging to our west and troughing over the eastern CONUS continuing. We will see short wave energy moving southeast on the back side of the trough at times that will bring additional showers an storms to our area for the Friday through Tuesday period. Timing of these features and the resulting convection is of course unclear this far out. Temperatures for Thursday into Saturday look to be a bit below normal, then the remainder of the period through Tuesday will likely see temperatures not far from normal for this time of year.

AVIATION

(12Z TAFS) Issued at 640 AM EDT Wed Jul 22 2026

The general trend for the next few hours will be showers/storms in NE TN as a front approaches from the north, impacting TRI with predominant MVFR conditions from showers, and IFR conditions possible at times in heavier showers. The slow movement of the front will keep showers at TRI through most of the day. The rain chance spreads south into TYS later in the morning and persists into the evening. CHA may only see scattered showers and storms in the area by the evening.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 90 72 86 71 / 70 70 60 30 Knoxville McGhee Tyson Airport, TN 85 69 85 69 / 90 70 40 20 Oak Ridge, TN 85 67 85 67 / 80 40 20 10 Tri Cities Airport, TN 82 65 82 65 / 90 60 30 30

MRX WATCHES/WARNINGS/ADVISORIES

NC...NONE. TN...Flood Watch through this evening for Anderson-Blount Smoky Mountains-Campbell-Claiborne-Cocke Smoky Mountains-Grainger- Hamblen-Hancock-Hawkins-Jefferson-Johnson-Knox-Loudon- Morgan-North Sevier-Northwest Blount-Northwest Carter- Northwest Cocke-Northwest Greene-Roane-Scott TN-Sevier Smoky Mountains-Southeast Carter-Southeast Greene-Sullivan- Unicoi-Union-Washington TN.

VA...Flood Watch through this evening for Lee-Russell-Scott VA- Washington VA-Wise.