textproduct: Huntsville

KEY MESSAGES

Updated at 1110 AM CDT Wed Sep 2 2026

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

NEAR TERM

(Rest of Today and Tonight) Issued at 1110 AM CDT Wed Sep 2 2026

A strong mid-level high will remain centered across eastern TN/western NC for the duration of the near term period, maintaining SE flow aloft of 5-15 knots between the anticyclone and a broad trough across the eastern Gulf. In the low-levels, our region will remain under the influence of surface high pressure across the southern Appalachians, which will result in a light SE wind across western portions of the CWFA and light/variable-calm flow elsewhere.

Although the resultant deep-layer SE flow regime will sustain a moist and unstable airmass (featuring PWAT values in the 1.7-1.9" range and CAPE of 1750-2250 J/kg), with no clear evidence of a lifting mechanism we expect dry conditions to prevail for most of the region. That said, gentle orographic ascent in the more rugged terrain of northeast AL/southern Middle TN may initiate the development of a few showers and thunderstorms this afternoon, but POPs even in this region remain around 10%. With only a scattered, high-based cumulus field anticipated today, current temperatures appear on track to range from 90-94F in elevated terrain to 94-98F in the valley (with urban heat islands perhaps reaching 98-100F). Although efficient boundary layer mixing may force dewpoints into the mid 60s for much of the region, we will make no changes to the current Heat Advisory to highlight heat index in the 102-106F range (perhaps 106-110F in urban locations).

Any afternoon convection that manages to develop later today will dissipate quickly between 0-2Z, with mostly clear skies and dry conditions expected overnight. Lows will be in the 72-76F range, with calm winds supporting development of patchy, early-morning fog (particularly in the valleys of northeast AL).

SHORT TERM

(Thursday through Friday night) Issued at 1110 AM CDT Wed Sep 2 2026

Latest short range model guidance suggests that a mid-level high will remain centered to the immediate northeast of the TN Valley on Thursday/Thursday night, as a broad trough to our south begins to retrograde slowly westward into the central/western Gulf. As a lower-amplitude easterly wave tracks westward across the northern FL Peninsula and into the northeastern Gulf (in the flow between the high to its northeast and trough to its southwest), a related surface trough will likely focus a greater coverage of showers and thunderstorms across north FL and adjacent portions of the northeast Gulf Coast tomorrow, with some indication that a subtle low-level confluence axis may result in a slight increase in the coverage of afternoon showers and thunderstorms across our region, as well. Due to some loose agreement in the location of this feature in various members of the HREF, we have increased POPs into the 10-20% range for much of northwest AL/southern Middle TN. Regardless of storm coverage, DCAPE in the 1200-1400 J/kg range coupled with steep low-level lapse rates suggest that locally damaging downburst winds could occur with the strongest cells. For locations that do not experience a cooling shower or thunderstorm, it will be another hot/humid day featuring highs in the m-u 90s and similar heat index values (compared to today).

During the period from Friday-Friday night, the mid-level high to our northeast is predicted to weaken considerably as ridging aloft becomes established across the southern Great Plains. Due to the more favorable environment for updraft growth in this scenario, a similar coverage of afternoon showers and thunderstorms may occur on Friday (especially as PWAT values could increase to around 2" by this point). However, POPs will be left in the 10-20% range until details regarding a forcing mechanism become more clear. High temperatures will once again reach the m-u 90s (with similar heat index values) and Heat Advisory will remain in effect through the period.

LONG TERM

(Saturday through Tuesday) Issued at 813 PM CDT Tue Sep 1 2026

The upper level ridge over much of the central and southeastern US will persist into this weekend; however, it looks like an upper trough tries to dig south over the Northeast, potentially breaking down the ridge over the Appalachians, Ohio Valley, and Tennessee Valley somewhat during this time. This may be short- lived, since synoptic guidance suggests that the ridge will build back over the Southeast through early next week. At the surface, high pressure over the Appalachians may be overtaken by a backdoor cold front slated to move into the region from the northeast by Sunday. Some guidance hints that this feature may bring enough moisture and lift with it to produce at least a low chance of showers and storms this weekend, but these trends will be monitored. By early next week, surface high pressure builds back over the Appalachians as the upper ridge takes hold over the region once again.

Overall, the hot and humid conditions are expected to continue through the long term period. Expect highs in the mid to upper 90s through the weekend with not much relief at night as lows merely dip into the upper 60s to lower 70s. These temperatures, along with dew points in the lower to mid 70s, will result in heat indices in the 100-106 degree range along with WBGTs in the mid to upper 80s (some spots around 90 degrees) and Moderate to Major HeatRisk (levels 2 and 3 of 4) for most of north Alabama and southern middle Tennessee. By early next week, the aforementioned backdoor front may temper the heat and humidity slightly. Highs in the lower to mid 90s with dew points in the upper 60s to lower 70s are anticipated, keeping the HeatRisk in the Moderate Risk category, heat indices generally between 98-103 degrees, and WBGTs solidly in the 83-87 degree range. Ultimately, the current Heat Advisory runs through Saturday evening; however, we will be monitoring if a further extension into Sunday becomes necessary.

Remember to practice heat safety, especially if you work outside or have outdoor activities! Stay hydrated, take plenty of breaks in the shade, and never leave people or pets in vehicles!

AVIATION

(12Z TAFS) Issued at 614 AM CDT Wed Sep 2 2026

VFR conditions will persist through the TAF period with clear skies and light/var winds.

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.