textproduct: Huntsville

KEY MESSAGES

Updated at 1105 PM CDT Mon Sep 7 2026

- Low chances for showers and thunderstorms will return to the northern part of the forecast area Thursday and Thursday night.

- As a moist airmass returns to the region, chances for showers and thunderstorms will increase to 40-60% on Friday/Saturday afternoons, before falling into the 20-40% range Sunday/Monday. Lightning and heavy rainfall will be the main impacts from the storms.

- NWS Heat Risk will remain in the Minor to Moderate category throughout the forecast period.

NEAR TERM

(This Evening through Tuesday) Issued at 1105 PM CDT Mon Sep 7 2026

In the mid/upper-levels, weakening northeast flow aloft will gradually veer to the ESE by sunrise as our region begins to experience increasing influence from a strengthening subtropical ridge across the southern Great Plains (which will become centered over the TN Valley by the end of the period). In the low-levels, surface high pressure (which translated southeastward into the northern Mid-Atlantic states earlier today in the wake of a departing northern stream trough) will strengthen overnight, with pressure rises expected in the lee of the central/southern Appalachians. As this occurs, southeasterly flow will continue to become established from E-to-W this evening, and although there remains a very low chance for development of a shower or two in the vicinity of the naturally-induced streamline confluence axis as it progresses through northwest AL, probabilities for this to occur are in the 10-20% range. In the wake of this feature, a broken deck of lower-level stratocumulus clouds will spread west- northwestward over the TN Valley, with a few sprinkles of rain (or perhaps a light shower) possible as well, but chances for measurable rainfall at any one location remain 5-10%. As the SE flow begins to advect a drier continental airmass into the region, dewpoints will fall into the l-m 60s across the east by 12Z, with overnight lows ranging from the m60s in this portion of the forecast area to the l70s in the west.

The low-level SE flow regime (described above) will strengthen as mixing begins after sunrise, with gusts up to around 20 MPH expected for much of the day. Although the regime of partly-mostly cloudy skies and a few sprinkles of rain (or light showers) will continue for much of the late morning period, clouds will begin to disperse from E-to-W during the afternoon hours. This will provide sufficient time for afternoon highs to reach values only a couple of degrees cooler (compared to today), with most valley locations in the u80s-l90s.

SHORT TERM

(Tuesday night through Thursday night) Issued at 1105 PM CDT Mon Sep 7 2026

Short range model consensus suggests that the TN Valley will remain under the influence of a strong 500-mb ridge during the period from Tuesday night-Wednesday night, as its center migrates slowly eastward into the southeastern Atlantic Coast. At the surface, a weakening dome of high pressure will shift slowly eastward off the Mid-Atlantic Coast, but should provide sufficient influence to sustain light SSE winds and a plume of relatively lower dewpoints across our region. This will translate to a continuation of dry weather, with morning lows in the u60s-l70s (perhaps a few degrees cooler in the sheltered valleys of northeast AL/southern TN) as afternoon highs rise back into the l-m 90s (with less morning cloud cover).

By Thursday and Thursday night, the subtropical ridge is predicted to weaken and shift eastward into the southwestern North Atlantic, allowing a light WSW flow to develop aloft. As this occurs, light SW flow will become established in the low-levels ahead of a cold front (attached to an occluding cyclone across northern Quebec) that will initially extend from eastern CO northeastward into southeastern Quebec. Although the front will exhibit very little (if any) movement, a prefrontal wind shift axis will focus the development of widespread convection (well to our north) on Wednesday night and Thursday, which should force the prefrontal wind shift axis to drift southeastward with time. This feature will likely initiate new clusters of showers and thunderstorms as it slowly approaches our CWFA, but with a very low probability that it will actually enter our region, we will only include a 20-30% POP (generally focused across northwest AL/southern TN). Due to the lingering presence of a drier (but gradually modifying) continental airmass across our region, CAPE will be on the low side (but certainly adequate for development of some thunderstorms). This, coupled with weak vertical wind shear, suggest that any storms will be unorganized and lightning should be the primary impact. Highs will remain in the l-m 90s on Thursday, with overnight lows once again in the u60s-l70s.

LONG TERM

(Friday through Monday) Issued at 1105 PM CDT Mon Sep 7 2026

Extended range model data suggests that a subtle low-level streamline confluence axis (initially positioned across the TN Valley) will lift northward into the OH Valley and lose definition during the period from Friday-Saturday night, in response to surface pressure falls across the southern High Plains. This, along with SW flow aloft (provided by a weak mid- level trough drifting eastward over the Lower MS Valley), will force PWAT values back into the 1.8-2" range, leading to a general increase in the coverage of showers and thunderstorms both days. With no clear evidence of synoptic scale forcing for ascent, subtle deep- layer warm/moist advection and mesoscale boundaries will likely be the source of unorganized convection (largely tied to the diurnal warming cycle, but with some potential for convection to persist at night, as well).

On Sunday and Monday, there are indications that the Atlantic subtropical ridge will begin to strengthen as it retrogrades westward into the southeastern CONUS. Although this could potentially have a negative influence on the overall coverage of afternoon convection, low-level moisture return will improve as southerly flow becomes established within the warm sector of a low tracking northeastward into the Upper MS Valley. With dewpoints returning to the l-m 70s, PWAT values will continue to rise above 2" and this coupled with collapsing steering currents aloft may enhance the risk for locally heavy rainfall and flooding during this period. Due to increased rain chances, highs will fall back into the u80s-l90s, as overnight lows remain in the u60s-l70s.

AVIATION

(06Z TAFS) Issued at 1252 AM CDT Tue Sep 8 2026

There have been no changes to previous aviation forecast reasoning, as a lower deck of broken stratocumulus clouds will continue to expand northwestward into the region early this morning. This will provide VFR cigs arnd 5 kft (and perhaps a few sprinkles of rain or lgt SHRA) that should persist thru early-mid aftn before dispersing. SE surface flow will increase to 10G18 kts beginning arnd 14Z, but should subside by sunset.

HUN WATCHES/WARNINGS/ADVISORIES

AL...None. TN...None.