textproduct: Huntsville

KEY MESSAGES

Updated at 1020 AM CDT Thu Jul 23 2026

- Flood Watch in effect for areas east of I-65 through 7 PM Friday.

- Low to medium chances of showers and storms today; will increase to medium to high chances by Friday and Saturday.

- Heat Risk increases to Moderate Risk (level 2 out of 4) Sunday/Monday and then Major (level 3 out of 4) on Tuesday

NEAR TERM

(Tonight) Issued at 233 PM CDT Thu Jul 23 2026

There have been no significant changes to the forecast since the morning update. Showers have remained quite low in coverage with limited vertical growth. Thunderstorm chances for the rest of the day are quite low given recent radar trends. Thick cloud cover overhead has limited heating with temperatures in the low to mid 70s across southern middle TN, upper 70s along and north of the TN River, and low to mid 80s south where some breaks in the clouds have allowed peeks of sunshine through.

Previous Discussion: Sfc observations this morning show a stalled boundary sitting across the Tennessee Valley with a cooler and drier airmass sitting just to our north across middle Tennessee. Satellite imagery has thick cloud cover stretching along the boundary. CAMs show showers and storms developing along a differential heating boundary along the southern fridge of the cloud cover as we heat up later today, which is roughly along and south of the Tennessee River. While no severe storms are forecast this afternoon, pwats are between 2-2.2 inches and corfidi up-shear vectors are around 10 kts. This would suggest favorable conditions for back building storms with high rain rates resulting in localized flash flooding. As a result, a Flood Warning remains in effect through 7pm Friday. Further north, light rain is expected on and off throughout the day. Cloud cover and precip today will keep us a bit cooler than previous days with afternoon highs only rising into the lower 80s north of the Tennessee River and mid to upper 80s south.

Showers diminish this evening with the loss of daytime heating. Given the very moist conditions cannot fully rule out at least a low/medium chance for precip overnight, but coverage should be quite isolated. Persistent cloud cover will also limit any fog

SHORT TERM

(Friday through Saturday) Issued at 1020 AM CDT Thu Jul 23 2026

Upper level ridging to our west continues to be dominant as we head through the short term period. This keeps northwest flow aloft over the Tennessee Valley. A subtle shortwave ejects through the local forecast area on Friday and combined with the stalled boundary over northern Alabama leads to medium to high chances for showers and storms. The latest trends in the morning CAM runs have pushed the boundary further to the south. This would shift the most favorable axis for heavy rainfall south of the Tennessee River and perhaps even into portions of central Alabama. If this was to occur, the flooding risk would decrease across northern Alabama. However, as we have seen in the past small mesoscale features can shift where the heaviest rainfall occurs, therefore it is still important to keep an eye on the latest forecast and prepare for flash flooding.

Riding along the northwest flow, another shortwave pushes through the area on Saturday. This will once again provide medium chances for showers and storms, especially during the peak heating hours. Confidence in coverage of storms is still quite low with perhaps the most favorable area being across northwest Alabama. Therefore, at this time there is no plan to extend the flood warning.

LONG TERM

(Saturday night through Wednesday) Issued at 923 PM CDT Wed Jul 22 2026

A ridge dominated upper level pattern will prevail across much of the Lower-48 as we head into next week. Forecasts of 500mb heights late Sat indicated strong upper ridging sprawled from the Desert SW, southern Rockies, and the High Plains from Wyoming to the Big Bend. A deep upper low over the Hudson Bay was producing troughing which extended southward along the East Coast. This firmly places the greater Tennessee Valley in a NW flow aloft, which appears will continue into the middle of next week. A number of passing upper level disturbance within this stream will help contribute to convection impacting the area early in the period. Exact timing and placement of them is rather difficult, so am depending upon ensemble and blend guidance versus deterministic output.

At the surface, a frontal boundary now moving in a NW-SE manner across the area should return as a warm front late Fri into Sat. This will bring additional lower level moisture from the Gulf of America further inland. Output from the NBM has precipitable water amounts of over 2" across the forecast from Sat evening into Sun morning. With passing upper level support, there will be good chances for numerous showers and thunderstorms to impact the Tennessee Valley. Some of the storms could become strong. Of greater worry is rainfall output in such a humid environment. Excessive rainfall and a potential of flooding cannot be ruled out; which will be dependent upon how much rainfall occurs beforehand. The frontal boundary per DESI and NBM guidance should move southward again late Sun into Mon, with shower activity ending for the start of a new work week.

Daily temperatures into the middle of next week appear will be on the rise, in part thanks to the strong upper ridge just to our west. As shower activity ends on Sun, the heat will return. Highs to start a new week should range from the mid/upper 80s to the lower 90s west. Even warmer conditions are expected for the Mon-Wed timeframe, with highs all three days mainly in the low/mid 90s, and lows in the low/mid 70s. Heat index values on Sun should range from the mid/upper 90s east to 107 in the more urbanized spots. Another need for Heat Advisories maybe needed Sun, but appear more likely next Mon/Tue, with values ranging from the upper 90s to 109 in the hottest spots. They could be some relief by the midweek, as another frontal boundary moves across the area from the north. This boundary will also bring lower end rain chances back to parts of the Valley.

AVIATION

(00Z TAFS) Issued at 646 PM CDT Thu Jul 23 2026

A frontal boundary oriented west to east across the area should remain nearly stationary tonight, then move more southward on Fri. VFR conditions are expected into the overnight. Most of the models were hinting at a lower altitude clouds returning before daybreak Fri, with CIGs to reduced to MVFR. Confidence is low on showers returning Fri. Some of the guidance shows an uptick of shower/ thunderstorm formation in the late morning and afternoon. Given the uncertainty, have maintained a PROB30 group with MVFR VSBY/CIG reductions from convection. Shower activity should fade in the late afternoon, with VFR weather returning late in the TAF.

HUN WATCHES/WARNINGS/ADVISORIES

AL...Flood Watch through Friday evening for ALZ006>010-016.

TN...Flood Watch through Friday evening for TNZ076-096-097.