textproduct: Huntsville

KEY MESSAGES

Updated at 1035 AM CDT Sat Aug 15 2026

- Dangerous heat will impact the Tennessee Valley through the middle of next week, with Major (Level 3/4) to Extreme (Level 4/4) heat impacts forecast.

- A Heat Advisory is in effect for all of northern Alabama and southern middle Tennessee through 7 PM Monday, with extensions potentially into the middle of next week.

- There may be a window for Extreme Warning Criteria being met on Monday. However, the timing of a frontal boundary moving south will have a big impact on that. If it doesn't move into southern middle Tennessee until the evening hours, then mixing may keep heat index values mainly between 105 and 110 degrees. - A Marginal (1 out of 5) risk for severe thunderstorms is forecast across Northern Alabama near and east of I-65 Monday afternoon.

NEAR TERM

(Rest of tonight and Sunday) Issued at 1042 PM CDT Sat Aug 15 2026

Currently any convection continues to be well southeast of the area. Some mid/high cloud cover is being advected northward from activity over southern Alabama at this hour. However, this activity should continue to dissipate over the next few hours and would expect cloud cover to do the same this far north. With light winds expected tonight, this should have little effect on radiational cooling. Temperatures have dropped into the mid to upper 70s at 10 PM. This is still very warm for this time of night. Thinking we could at least see some brief patchy fog between now and 1 AM or so. Think this would be more pronounced east of the I-65 corridor though.

Models continue to drop dewpoints given WSW to W flow seen around 925 mb. This and valley drainage should allow dewpoints to drop into the upper 60s to lower 70s after midnight into the day break hours on Sunday. This should help keep fog from becoming widespread or dense Sunday morning.

Newer 00Z guidance mainly keeps 925 mb temperatures climbing to around 28 or 29 degrees in the afternoon. This is a bit cooler than previous runs. Based on today's cooler than expected temperatures, highs mainly in the 95 to 98 degree range may be more realistic. Believe mixing of drier air to the surface in the afternoon should keep heat index values in the 105 to 110 degree range mainly, so at this time a Extreme Heat Warning is not expected to be needed on Sunday.

SHORT TERM

(Sunday night through Tuesday) Issued at 1042 PM CDT Sat Aug 15 2026

Another very warm night is expected on Sunday night into Monday morning. This could be aided slightly by low level warm air advection ahead of a front to our north. Lows are only expected to drop into the mid to upper 70s. Some patchy fog could occur through around midnight. However, lower dewpoints should keep this very patchy in nature.

During the day on Monday, there is some question concerning how quickly a weak cold front moves southeast into northern Alabama. If this front is slower and doesn't move into the area until the very late afternoon to early evening hours, then higher dewpoints may be focused more into the evening hours. This would likely keep us in a general Heat Advisory on Monday. However, if the front moves south quicker and focuses higher dewpoints over the area during the early to mid afternoon hours, heat index values over 110 degrees could be met in some areas. Overall good instability is forecast to be in place. However, better shear (25-30 knots) in most guidance remains closer to the Carolinas, eastern Tennessee, and NE Georgia. If this is the case, an organized severe threat looks very unlikely. However, a strong or severe storm could occur given the instability and forcing moving into the area (mainly east of the I-65 corridor if severe storms are realized. Timing of activity is uncertain given the spread in the movement of the front in guidance. Right now though, leaning toward a drier solution and arrival of the front into northern Alabama during the early evening hours.

Northwest flow is expected to develop and remain in place Tuesday and Tuesday night. Some models are showing some afternoon/early evening showers/storms south of the Tennessee River into southern Alabama on Tuesday afternoon. Some show no precipitation at all. Currently, NBM is going the drier route. Either way, highs should be a bit cooler, only climbing into the lower to mid 90s. Dewpoints should mix again into the upper 60s to lower 70s. This should keep afternoon heat index values mainly climbing to around 106 or 107 degrees in some areas.

LONG TERM

(Tuesday night through Saturday) Issued at 1042 PM CDT Sat Aug 15 2026

The weather looks dry on Wednesday, as NW flow continues and otherwise conditions look similar to temperatures and heat index values expected the previous day.

Even cooler temperatures are expected towards the end of next week, as another stronger front moves southeast into the area and stalls. Shower and thunderstorm chances may increase more as we get closer to this period. Highs in the upper 80s to lower 90s are expected with the increasing cloud cover and precipitation chances.

AVIATION

(06Z TAFS) Issued at 1227 AM CDT Sun Aug 16 2026

Upper level ridging situated over the southern Lower-48 will control the general weather for the start of a new week. Broad surface high pressure off of the SE Coast will provide a light westerly flow across the TN Valley. VFR conditions are forecast for the terminals today. Although late night fog is unlikely at KMSL, other more sheltered valley locations could be impacted by fog early this morning. Fog that forms will quickly dissipate after daybreak.

HUN WATCHES/WARNINGS/ADVISORIES

AL...Heat Advisory until 7 PM CDT Monday for ALZ001>010-016.

TN...Heat Advisory until 7 PM CDT Monday for TNZ076-096-097.