textproduct: Huntsville

KEY MESSAGES

Updated at 359 AM CDT Sun Aug 16 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 Slight (2 out of 5) risk for severe thunderstorms is forecast across eastern Franklin County Tennessee and portions of far northeast Alabama, with a Marginal (1 out of 5) risk from the Quad Cities of northwest Alabama and eastward Monday afternoon.

NEAR TERM

(Today) Issued at 359 AM CDT Sun Aug 16 2026

Strong upper level ridging was sprawled over the southern CONUS, or from around the United States/Mexico border to off of the SE Coast. This ridge with maximum 500mb heights around 598 decameters was helping to bring very warm to hot conditions across the Tennessee Valley. Although we are near 4 AM, night-time low temperatures were only in the low/mid 70s with generally calm winds. With dewpoints generally a tad cooler and a few more hours before daybreak, there is some opportunity for patchy fog formation. If fog develops, it should remain patchy in coverage and confined to fog prone locations. Any fog that forms should dissipate shortly after sunrise.

With upper ridging holding strong, another very warm to hot day is expected, with highs rising into the mid/upper 90s. Dewpoints should fluctuate in the lower 70s during the day. Our thinking is that they'll mix a bit lower this afternoon, which would provide a little relief from very hot heat indexes (HI). That said, dewpoints closer to 70 will support HI values of 103-106, values near the mid 70s could produce near 110 HI. We are keeping the faith with strong subsidence, thus dry weather is expected.

SHORT TERM

(Tonight 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.

Updated thoughts on severe weather Monday 359 AM CDT CDT Sun Aug 15 2026

The Day-2 Convective Outlook has raised a severe weather risk to a Slight Risk (2 out of 5) for the eastern half of Franklin County TN, and eastern Jackson and DeKalb counties in AL on Monday. A Marginal Risk (1 out of 5) covers areas from the Quad Cities of NW Alabama and points eastward. Very strong heating along with more lower level moisture will produce very unstable conditions. Adding to the mix is a cold front moving southward towards the area. This front nearing the region will help with convection development Monday afternoon and evening. Some of the storms that form could become severe, with the main risk of strong to damaging outflow wind gusts, aka downburst mode.

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

(12Z TAFS) Issued at 630 AM CDT Sun Aug 16 2026

Strong upper level ridging will help continue VFR conditions and no weather of consequence across the TN Valley. Surface high pressure off of the east coast will provide a light westerly flow across the area for the TAF. Strong daytime heating should result in a few to scattered cumulus mainly this afternoon and early evening.

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.