textproduct: Huntsville

KEY MESSAGES

Updated at 937 PM CDT Fri Sep 4 2026

- A Heat Advisory remains in effect through 8 PM Sunday due to Major to Extreme HeatRisk, along with afternoon heat indices rising up to 105-109 degrees in portions of the forecast area.

- A low chance (30% or less) of thunderstorms are forecast Saturday afternoon into the late evening, with a low chance of some becoming severe. Damaging winds will be the primary threat is any strong to severe storms.

NEAR TERM

(Today) Issued at 301 AM CDT Sat Sep 5 2026

Calm winds and low dew point depressions early this morning has led to patchy fog development, particularly in sheltered valleys. After dissipating shortly after sunrise, diurnal cumulus fields will form in the late morning. Extra synoptic forcing for ascent will be present due to a strong cut off low pressure system over New England propelling a shortwave trough across the Eastern CONUS. As a result, the upper level ridge axis will slide westward. This will not be sufficient for a reprieve from the heat, and temperatures in the upper 90s, potentially touching 100, are expected this afternoon before convection initiation.

Thermodynamic support will be present for strong to severe storms, which have a 20-30% chance of forming over any given location this afternoon due to the aforementioned shortwave. Low level lapse rates approaching 10 C/km and SBCAPE values of 2500-3000 J/kg will support rapidly growing updrafts. Coupled with weak steering flow and PWATs of 1.8", strong downbursts with damaging winds of 60-70 mph represent a reasonable worst case scenario this afternoon. Heavy rainfall may also lead to brief, localized flooding that should rapidly drain as the storms dissipate. Convective coverage will increase around 2 PM but should wane after sunset, unless outflow boundary interactions lead to an isolated storm as late as 10 PM.

SHORT TERM

(Saturday night through Monday) Issued at 937 PM CDT Fri Sep 4 2026

Thunderstorms should gradually come to an end by the late evening hours Saturday with the loss of diurnal support. However, sub- severe thunderstorms will likely remain in the area through the early morning hours- bringing additional heavy rainfall as well as lightning with a low chance of gusty winds. While our Heat Advisory was slated to end Saturday night, it has now been extended to Sunday night as the Tennessee Valley remains under the influence of an upper level ridge and subsequent above normal temperatures. High temperatures on Sunday are forecast to reach the upper 90s with heat indices up to 109 degrees. A cold front should push through the area Sunday afternoon, bringing slight relief from the heat by Sunday night as low temperatures drop into the upper 60s to lower 70s (as opposed to mid 70s the past several nights). Highs on Monday are still forecast to reach the 90s, however, heat indices should be capped near 100 degrees as a relatively drier airmass shifts southward into the area. Low chances (30% or less) of thunderstorms remain in response to diurnal heating Monday afternoon.

LONG TERM

(Monday night through Friday) Issued at 937 PM CDT Fri Sep 4 2026

Heat will persist through the long term as well. The vast ridge of high pressure that is centered over the Southern Plains and Mid MS Valley will expand eastward to encompass the rest of the Southeast early this week. Mid week, a trough will swing through the southern Canadian prairie provinces dampening the ridge, and sfc high pressure will set up along the Appalachians. This set up could create a CAD expanding into NE AL and portions of Southern Middle TN. If this comes to fruition, adjustments to POPs (slight increase) and temps (slight decrease) would be needed. Regardless, it looks like temps will remain in the 90s throughout the week, which is par for the course this month, but running a tad higher than seasonal norms which is 87-88 degrees. Heat index values will hover around 100 degrees and the NWS Heat Risk will be a level 2 (Moderate Level) for the large majority of us. Remain heat smart: slow down, cool down, stay hydrated and NEVER leave people or pets in vehicles.

AVIATION

(06Z TAFS) Issued at 1240 AM CDT Sat Sep 5 2026

Areas of lower clouds are briefly overspreading the TN Valley but are expected to quickly move out of the region before the new TAF period begins. Patchy fog has a low chance (20-30%) of forming before sunrise. Otherwise, isolated to scattered storms are forecast with a 20-30% chance of impacting terminals with gusty winds and lightning during the afternoon and early evening.

HUN WATCHES/WARNINGS/ADVISORIES

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

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