textproduct: Huntsville

KEY MESSAGES

Updated at 1016 AM CDT Thu Sep 3 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.

- A few thunderstorms may occur both this afternoon and Friday afternoon, with a slight increase in coverage expected on Saturday. Regardless of the number of storms, conditions will be favorable for locally damaging winds, heavy rain, and frequent lightning on a daily basis.

NEAR TERM

(Rest of Today and Tonight) Issued at 1016 AM CDT Thu Sep 3 2026

A mid-level high will remain centered across western portions of NC/SC throughout the near term period, as a broad but gradually strengthening trough retrogrades across the eastern/central Gulf. To the east of the trough, a lower-amplitude easterly wave (currently situated off the Atlantic Coast of FL) will progress northwestward into southern GA/north FL but should weaken with time as it encounters a region of increasingly confluent flow.

At the surface, our forecast area will largely remain under the influence of a high across the southern Appalachians, with light SE winds during the daylight hours transitioning to calm flow at night. However, a subtle pressure trough/streamline confluence axis (related to the retrograding trough to our south) is predicted to lift northwestward through the CWFA late this afternoon/early this evening and may provide sufficient low-level ascent for the development of a few showers and thunderstorms (beginning in the 18-20Z timeframe). Although OZ CAMs indicate that storm coverage will be comparatively lower in the vicinity of the boundary across our region (and much higher from southwestern AL into the Arklamiss), steep low-level lapse rates, MLCAPE in the 2000-2500 J/kg range and PWAT values in the 1.7-1.9" range suggest that locally damaging downburst winds and frequent lightning may accompany the strongest cells. In the absence of convective influences, it will be another hot/humid day featuring highs in the m-u 90s. Similar to yesterday, efficient mixing will likely lower dewpoints into the m60s for many locations (perhaps keeping HI in the 100-105F range away from urban heat islands). However, we have no plans to alter the ongoing Heat Advisory at this point.

Current thinking is that any lingering showers/thunderstorms this evening will dissipate between 0-2Z, but with the potential for a low-level convergence axis in our general region, it would not be out of the realm of possibility for isolated convective cells to persist a bit later into the evening. Overnight lows will once again be in the m60s (with a few l60s in the east), with brief development of patchy fog around sunrise in valleys and near large bodies of water.

SHORT TERM

(Friday through Saturday night) Issued at 1016 AM CDT Thu Sep 3 2026

During the period from Friday into Friday night, the mid-level high to our northeast is predicted to weaken as a deepening northern stream trough digs southeastward into the Canadian maritime provinces. However, a new anticyclone aloft will become established over the southern Plains, and the upper trough over the central Gulf will continue to advance slowly westward as its related surface wave drifts very slowly northwestward in the vicinity of the LA coast. Although some afternoon/early evening showers and thunderstorms may certainly occur in our CWFA once again, concentration appears as if it will be highest in the vicinity of a low-level convergence axis (likely situated to our northwest) and across southern portions of the Gulf Coast states, where rich tropical moisture will spread inland within a deep south-southeast flow regime. Thus, we will keep POPs in the 10-20% range but should emphasize that thermodynamic parameters will remain sufficient for locally damaging downburst winds.

Northerly flow aloft will quickly become established and strengthen from Saturday into Saturday night, within the gradient between a high over the southern Plains and an amplifying trough to our northeast. Although this will advect drier air southward (resulting in a minor reduction in atmospheric moisture content), the environment will become more conducive for thunderstorms during this timeframe, especially as a lengthy outflow boundary (originating from a nocturnal MCS over the Lower Great Lakes/OH Valley Friday night) approaches the region from the northeast Saturday afternoon. As a result, POPs have been increased into the 10-30% range, and this activity could linger well into the evening hours (especially if the outflow boundary actually enters our forecast area). In spite of lower PWAT values, conditions will remain favorable for damaging wind and frequent lightning. Regarding temperatures, very little fluctuation is expected over the course of the short term period, with afternoon highs in the m-u 90s and overnight lows in the l-m 70s. Although mixing may lower dewpoints on a daily basis, HI should remain sufficiently high to warrant continuation of the current Heat Advisory through Saturday evening.

LONG TERM

(Sunday through Wednesday) Issued at 852 PM CDT Wed Sep 2 2026

The upper-ridge looks as if it may temporarily shift back to the west early next week. However, this comes with a word of caution. At least moderate (Level 2/4) heat impacts will continue through the middle of next week as highs in the low to mid 90s are still forecast each day. The main difference will be dewpoints which will be modified in wake of a shortwave passage Saturday night, dropping the from the mid 70s into the upper 60s. This will keep our peak heat index values around 100 degrees each day as opposed to 105-110. With ridging still the dominant feature over central/southern portions of the CONUS, an overall dry forecast will still remain intact. However, with the Tennessee Valley being on the edge of the ridge, low chances (20%) of diurnally driven showers and thunderstorms will exist each afternoon Sunday through Wednesday.

AVIATION

(18Z TAFS) Issued at 1238 PM CDT Thu Sep 3 2026

Development of scattered Cu will continue this afternoon, with a subtle low-level convergence boundary lifting northward into the region likely to support a slightly greater coverage of SHRA/TSRA (compared to previous days). Although storms could certainly be impactful (featuring AWW-caliber wind gusts and frequent lightning) should they cross an airfield, we will not mention convection in the current TAFs due to uncertainties regarding coverage. However, short term amendments may be necessary through dissipation between 0-2Z. Aside from sct Ci, mostly clear skies and calm winds will be favorable for development of BR/FG early Fri morning (especially in locations that receive wetting rains today). A light SE flow will return late in the period, with redevelopment of a Cu field expected by 16Z.

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.