textproduct: Huntsville

KEY MESSAGES

Updated at 1032 AM CDT Mon Sep 14 2026

- Moderate (Level 2/4) NWS HeatRisk values are expected for the majority of the forecast period. However, Major (Level 3/4) values are expected across parts of northwest and north-central AL (as well as southern Middle TN) today-Wednesday.

- A Heat Advisory is in effect from 11 AM through 8 PM on Tuesday for portions of the forecast area.

NEAR TERM

(Rest of Today and Tonight) Issued at 1032 AM CDT Mon Sep 14 2026

In the mid/upper-levels, a strengthening subtropical ridge (initially across central MS/AL) will develop northeastward, becoming centered across the Cumberland Plateau region of Middle/East TN by the end of the period. As this occurs, light NNE flow aloft will progressively veer to SE and increase by 12Z Tuesday. In the low-levels, a surface high across Lower MI will weaken a bit as it translates eastward into the northern Mid- Atlantic states later today, with this feature expected to sustain a light NE flow across the TN Valley.

With a subtle surface trough located on the southern edge of the ridge expected to focus the greatest concentration of afternoon convection from eastern MS westward into southern AR/northern LA today, we expect rain chances to remain very low across our forecast area. Nevertheless, we will leave a 10-15% POP intact for our western zones to account for uncertainty regarding the location of convective initiation to our immediate west early this afternoon, and will leave a 5-10% POP elsewhere as a few showers may also evolve in the higher terrain of northeast AL/southern Middle TN. In spite of PWAT values in the 1.5-1.6" range and MLCAPE perhaps reaching 1000-1500 J/kg for much of the region this afternoon, chances for thunderstorms appear as if they will be limited significantly by a developing stable layer beneath the strengthening 500-mb high and around the 15 kft level. Afternoon highs will range from the u80s-l90s in elevated terrain to the m-u 90s in the valley, with Heat Index perhaps hitting 105F in urban locations and in a few communities across northwest AL.

Should any showers or thunderstorms develop in our region this afternoon, rapid dissipation is anticipated around 0Z. Thus, we expect mostly clear skies and a light ESE wind to prevail for much of the night. Overnight lows will be in the m60s-l70s (coolest in the east where a slightly drier airmass originating from a CAD across VA/NC/SC may enter the region). Patchy mist and fog may develop once again in rural portions of the CWFA between 10-13Z.

SHORT TERM

(Tuesday through Wednesday night) Issued at 1032 AM CDT Mon Sep 14 2026

During the timeframe from Tuesday-Wednesday, a subtropical high will continue to gradually strengthen across eastern TN before weakening a bit and retrograding westward into the Mid-South late Wednesday and Wednesday night. As this occurs, light S-SW flow aloft will become light/variable prior to a notable increase in N-NE flow Wednesday night as a developing upper low between Bermuda and the southeastern Atlantic Coast advances southwestward toward the FL Peninsula. At the surface, our region will remain under the influence of a high as it drifts slowly eastward off the New England coast and into the northwestern Atlantic. Although a slightly more contracted pressure gradient will support a minor increase in SSE flow on Tuesday and Tuesday night, this will have little to no impact on low-level moisture, with dewpoints expected to remain in the u60s-l70s. However, with broad scale subsidence related to the anticyclone aloft expected to become more pronounced tomorrow, POPs will be even lower than today and generally around 5%. Thus, we expect afternoon temperatures to be a degree or so warmer for most of the region and a Heat Advisory is in effect from 11A-8P (although HI values near or slightly in excess of 105F should remain confined to urban locations and small parts of northwest AL).

With the influence of the ridge expected to begin diminishing on Wednesday afternoon, conditions will become somewhat more favorable for development of afternoon showers (and a few thunderstorms) from the Cumberland Plateau of Middle/East TN southward into the higher terrain of northeast AL, with developing northeasterly steering flow perhaps allowing some of this activity to spread southwestward into northern AL early Wednesday evening. Aside from this, we are anticipating no significant changes to the synoptic environment, with afternoon highs on Wednesday once again reaching values similar to both today and Tuesday, and overnight lows remaining in the m60s-l70s.

LONG TERM

(Thursday through Sunday) Issued at 901 PM CDT Sun Sep 13 2026

The TN Valley won't find a break from the heat in the Long Term. The lingering ridge across the Southeast will start to retrograde as a cut off low pushes into FL starting on Thursday. With a sfc high anchored across the east coast, highs will remain in the 90s through the week. However, the low will pull additional moisture into the region, pushing Heat Index values around 100 degrees, but at this time below any advisory criteria. The low will slide westward across the northern Gulf through the weekend, and this will allow for a front in the Ozarks and OH Valley to dip southward towards the TN Valley. Models still disagree on if the front will make it in or not this weekend and the outcome will have an effect on our temps, cloud cover, and our precip chances. If it moves through, we could have a quick break in the heat but increased rain chances, but if it remains to our north, hot and humid conditions will persist. Will stick with guidance that has the 90s lingering, heat index values still hovering around 100 degrees and low precip chances (15-25% Sat, 20-30% Sunday). However, trends will be monitored for future needed adjustments.

AVIATION

(18Z TAFS) Issued at 1239 PM CDT Mon Sep 14 2026

A diurnal Cu field has already begun to develop across the region early this aftn, and although isolated SHRA (or perhaps a TSRA) may occur at times (particularly across northwest AL), probabilities for occurrence remain too low to include in the forecast at either terminal. Any convective cells that manage to develop in our region should dissipate rather quickly around 0Z, leaving clear skies and a lgt E-SE flow overnight. Patchy BR/FG may once again develop in a few locations btwn 10-13Z, but based on persistence we will not include any vsby reductions in the forecast attm. Sfc flow will veer to SSE and strengthen to 5-10 kts late in the period, with redevelopment of Cu anticipated by 15Z.

HUN WATCHES/WARNINGS/ADVISORIES

AL...Heat Advisory from 11 AM to 8 PM CDT Tuesday for ALZ001>007.

TN...Heat Advisory from 11 AM to 8 PM CDT Tuesday for TNZ076-096.