textproduct: Huntsville

KEY MESSAGES

Updated at 930 PM CDT Thu Sep 17 2026

- A Heat Advisory is in effect through 8 PM Saturday across all of southern middle Tennessee and northern Alabama.

- NWS Heat Risk highlights Moderate (Level 2/4) to Major (Level 3/4) heat impacts through the weekend across the Tennessee Valley. Localized Extreme (Level 4/4) impacts may occur in urbanized areas.

NEAR TERM

(Rest of tonight and Friday) Issued at 930 PM CDT Thu Sep 17 2026

A tranquil evening is in store across the Tennessee Valley as the area sits underneath a large amplitude mid and upper level ridge. Sfc high pressure remains centered over the Southeast and as a result, light winds and clear skies are forecast tonight. Temperatures this evening have fallen quickly after sunset thanks to the relatively drier air with overnight lows expected to drop into the lower 70s.

Another rinse and repeat day is forecast on Friday with very hot temperatures expected as afternoon highs rise into the mid to upper 90s. The good news is that dewpoints will once again mix out during the peak heating hours and drop down into the mid to upper 60s. This keeps max heat index values between 100F-107F. However, with wet bulb globe temperatures in the upper 80s to around 90F and NWS Heat Risk at Moderate (level 3 out of 4) to Extreme (level 4 out of 4) in the metro area, dangerous heat will once again be the main concern of Friday. Therefore the Heat Advisory will continue through Saturday. Make sure to practice good heat safety by staying hydrated and avoiding long amounts of time in direct sunlight. While there is a very low chance of a stray shower across portions of NE AL tomorrow, the latest CAMs suggest the bulk of the precip should remain to the northeast of the local forecast area.

SHORT TERM

(Friday night through Sunday Night) Issued at 930 PM CDT Thu Sep 17 2026

As we head into the weekend the upper level ridge begins to break down and recede a bit to the west. At the same time, a weak low pressure system off the east coast of Florida begins to drift to the west. This will produce more favorable conditions for afternoon convection, especially east of I-65. At this time, no severe storms are expected given the weak shear profiles. However, cannot rule out a strong storm or two capable of gusty winds as DCAPE values rise above 1000 J/kg. Prior to any precip, temperatures will once again warm into the mid to upper 90s both Saturday and Sunday. Showers and storms will dissipate after sunset with the loss of daytime heating resulting in calm conditions overnight. Something to keep an eye on is the low chances for early morning fog in areas that receive rainfall during the day. Otherwise, mild and humid nights continue with overnight lows in the upper 60s to lower 70s.

LONG TERM

(Monday through Thursday) Issued at 930 PM CDT Thu Sep 17 2026

Extended range model solutions suggest that a 500-mb ridge will remain positioned across the forecast area on Monday. However, as we progress through the rest of the period, it is becoming increasingly likely the the southern edge of the mid-latitude westerlies will develop southward into our region, with indications of a flat subtropical ridge lying across the northern Gulf and development of an upper low (from phasing of 2-3 distinct northern stream shortwaves) over the Great Lakes. In the low-levels, a weak area of low pressure is predicted to migrate from the Mid-South into the TN Valley on Monday, before degenerating into a frontal wave as it lifts northeastward into the Upper OH Valley Monday night. Although the trailing cold front will make only gradual southeastward progression into the Ozarks and OH Valley by early Tuesday morning, mesoscale boundaries originating from extensive convection to our northwest should contribute to a higher coverage of thunderstorms across our CWFA Monday afternoon and evening. As surface pressures begin to rise within a high migrating eastward across southern Ontario/Quebec (and renewed cyclogenesis takes place over the eastern Great Lakes), the cold front will advance further southeastward on Tuesday, resulting in another episode of convection during the afternoon/evening hours. Sufficient CAPE will exist to support a risk for strong-locally severe thunderstorms both periods, especially given an increase in mid-level flow to 15-25 knots. As the cold front shifts further southeastward through the region Wednesday, light-moderate northerly flow will begin to advect a slightly cooler/drier airmass into the region, with highs on Wednesday and Thursday dropping back into the 85-90F range and lows falling into the l-m 60s.

AVIATION

(00Z TAFS) Issued at 544 PM CDT Thu Sep 17 2026

VFR conditions with light winds will continue through the TAF period. There is a very low chance of an afternoon thunderstorm tomorrow, especially over NE AL, but confidence is too low to include in the forecast.

HUN WATCHES/WARNINGS/ADVISORIES

AL...Heat Advisory until 8 PM CDT Saturday for ALZ001>010-016.

TN...Heat Advisory until 8 PM CDT Saturday for TNZ076-096-097.