textproduct: Huntsville

KEY MESSAGES

Updated at 1045 AM CDT Sun Aug 16 2026

- Dangerous heat will impact the Tennessee Valley through the middle of this 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 on the table in future updates through potentially mid-week. - A Slight (2 out of 5) risk for severe thunderstorms is forecast Monday across eastern Franklin County Tennessee and portions of far northeast Alabama, with a Marginal (1 out of 5) risk through most of the area.

NEAR TERM

(Tonight) Issued at 330 PM CDT Sun Aug 16 2026

The forecast remains on track with minor adjustments made to PoPs along and south of the TN river due to some pop up showers this afternoon. Have added a low chance (15% or less) of showers through the next couple hours. Otherwise, low temperatures are still on track to drop into the mid to upper 70s. Relatively dry dew point depressions should prevent widespread fog formation again tonight.

Previous Discussion: The primary concern continues to be heat as an upper level ridge procrastinates moving eastward and we remain in a favorable area for above normal temperatures. This afternoon's highs are forecast to warm into the mid to upper 90s with heat indices up to 102-109 degrees. Tonight, lows are forecast to drop into the mid to upper 70s, which will not provide much relief. A Heat Advisory continues through 7 PM Monday. Be sure to stay hydrated and seek shade when outdoors to avoid heat- related illness.

SHORT TERM

(Monday through Wednesday) Issued at 1045 AM CDT Sun Aug 16 2026

An area of low pressure pushing eastward through the Great Lakes region is forecast to bring an associated cold front southeastward into the Tennessee Valley and Appalachian region Monday night. Ahead of this, both heat and severe storms will be on the table as hazards Monday afternoon into the evening hours. Addressing the heat, highs are forecast to reach the mid to upper 90s yet again along with heat indices nearing 110. The recent HREF run has very low chances (less than 5%) of our area meeting or exceeding 110 degree heat indices Monday afternoon, with the most likely range being around 105-108 degrees. Thunderstorm development and coexisting cloud cover ahead of the cold front will be the factor to watch. If the front slows down and the thunderstorms are delayed, there is a low chance we could reach Extreme Heat Warning in some locations (especially urban heat island spots such as Huntsville). We have opted to hold off on upgrading for now, but do not rule it out in future updates as the forecast evolves.

Severe weather-wise, the Storm Prediction Center has included most of the area in a Marginal risk (level 1 of 5) and clipped portions of northeastern AL and southern middle TN in a Slight risk (level 2 of 5). The primary concern with any storms that are realized will be damaging winds up to 60 mph in addition to heavy rainfall and lightning. Model soundings continue to portray steep low level lapse rates (9+ C/km) combined with DCAPE values over 1100 J/kg as well as MLCAPE over 1400 J/kg. These factors, combined with the typical inverted V sounding profile, will attribute to an increased risk of downbursts through the afternoon into the early evening hours. PWAT values are in the range of 1.7-1.9", which is near 90th percentile per BMX sounding climatology. Combined with the forecast slow storm movement (less than 10 kts), heavy rainfall will bring a low chance of flash flooding which will primarily be in areas of poor drainage. Heavy downpours will cause temporary ponding of water on roadways, which will create hazardous driving conditions during and shortly after any rainfall. Shear continues to look less than impressive with a lack of low level vorticity and therefore not anticipating tornadoes to be a threat. Be sure to stay weather aware Monday and have multiple ways to receive warning information throughout the afternoon.

Tuesday through Wednesday, heat remains a hazard with highs forecast to reach the 90s both days along with heat indices up to 105 degrees. A low chance of an extension of the current Heat Advisory (valid through 7 PM Monday) exists if temperatures continue to trend higher. Otherwise, dry conditions are forecast through both days after the cold front shifts south of the area.

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

(18Z TAFS) Issued at 1134 AM CDT Sun Aug 16 2026

VFR conditions are forecast through the TAF period.

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.