textproduct: Morristown

KEY MESSAGES

Updated at 232 PM EDT Mon Jul 20 2026

- Isolated showers and storms through this evening. A few strong to marginally severe storms are possible, some of which could produce gusty winds and localized flooding.

- Cold frontal passage tomorrow into Wednesday may bring several rounds of showers and storms, with a wide range of potential hazard outcomes. See discussion below.

- Below normal temperatures and drier air will follow beyond Wednesday. Precipitation returns next weekend.

DISCUSSION

Issued at 232 PM EDT Mon Jul 20 2026

Isolated to scattered showers and storms are expected through this evening. A few storms could be strong to marginally severe. The main impacts with any stronger storms will be gusty winds to 40 mph and an isolated flooding potential.

The bulk of this discussion will focus on the Tuesday through Wednesday timeframe. There is a high level of uncertainty regarding the timing and potential impacts during this timeframe as there are various model solutions. Generally though, we are looking at the possibility of several rounds of showers and storms with the potential of strong to severe storms from Tuesday morning through Wendesday morning.

Tuesday morning:

We have an upper level trough and advancing cold front coming in from the Ohio River Valley. To our southeast we have high pressure out in the Atlantic and to our south a tropical disturbance along the Gulf Coast. Most models keep us dry during the early portion of the day but the 06Z and 12Z run of the HRRR are insistent on firing convection across northeast TN and southwest VA Tuesday morning. If convection fires, it will do so within an environment that is supportive of a few strong to severe storms. The main threats will be isolated damaging wind gusts and flooding. The probability of this scenario is low as most models do not show this.

Tuesday afternoon/late evening:

Models generally agree that a semi-organized to broken line of convection will be approaching our northern areas (northern Cumberland Plateau, northeast TN, southwest VA) from out of KY. This could be in the form of one or multiple lines. Ahead of this line, we may also see a few isolated storms pop up across the higher elevations of the east TN mountains, which a few of could be strong to severe. The big question for the activity out of KY is far south does it progress before it falls apart and loses its punch. Some models have the line greatly diminishing and some show a more organized and stronger line of convection moving down into our area. The best case scenario during this timeframe is that convection is weakening as it moves into our area and we only see a few strong storms with a low end threat for some isolated damaging winds and flooding. Worst case scenario, the line holds together and strong to severe storms affect a good portion of the area with several reports of damaging winds, flooding, and an isolated tornado.

Late Tuesday night/Wednesday morning:

The weather during this timeframe largely depends on how the earlier convection evolves and moves through the area. There is a concerning trend that I want to discuss though. The RRFS and NAM both generally show the afternoon/early evening convection mostly dissipating before it enters our area. Both of these models then show a new line of convection firing along the remnant outflow boundary from the earlier storms. This new line of convection then slowly sags south into our area during the overnight hours and remains into Wednesday morning, possibly becoming stationary. This scenario would likely be due to a slower frontal progression through the area, which would be due to high pressure in the atlantic and the tropical depression to our south (no where for the front to go). This would be a worst case scenario as it would lead to the training of showers and storms and heavy rainfall over the course of several hours, which would likely lead to some significant flooding. Again, this is worst case scenario. The more likely scenario is that a line of showers and storms have enough push behind them, from the front, that they move south at a decent progression. Even with this scenario though, isolated flooding is still possible due to recent rain and flooding across the area.

Bottom line, this is a highly uncertain forecast in terms of system evolution and the resultant hazards and their severity. Please be prepared for severe weather anytime between Tuesday and Wednesday morning and don't get caught off guard.

Following the mid-week cold front, Thursday will be very nice with low to mid 80s highs and dew points in the 60s under high pressure. Temperatures rise a couple of degrees into the weekend, but for the most part remain below normal. A shortwave cycling the top of the upper ridge Friday into Saturday, may bring precipitation chances back to the area and unfortunately increased dew points yet again. A possible boundary that could get hung up to our south may complicate things.

AVIATION

(18Z TAFS) Issued at 138 PM EDT Mon Jul 20 2026

Isolated showers and storms expected through this evening. Left PROB30s in at all sites for possible convection but this may be too aggressive given the isolated nature of the convection. TRI is currently MVFR at BKN025 but they could scattered out here in the next few hours. Fog is possible again at TRI overnight due to yesterday's rainfall but low confidence. Winds begin to pickup and become gusty at TYS and TRI toward the end of the period with gusts to around 20kts out of the southwest.

PRELIMINARY POINT TEMPS/POPS

Chattanooga Airport, TN 75 93 76 90 / 10 10 40 70 Knoxville McGhee Tyson Airport, TN 74 90 74 86 / 10 10 80 80 Oak Ridge, TN 73 90 73 86 / 20 20 90 70 Tri Cities Airport, TN 69 87 69 83 / 60 50 90 80

MRX WATCHES/WARNINGS/ADVISORIES

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