textproduct: Huntsville

KEY MESSAGES

Updated at 1142 AM CDT Wed Aug 5 2026

- A low-medium coverage of showers and thunderstorms is expected today, ranging from 10-30% in northwest AL to 40-60% elsewhere. Occasional lightning and locally heavy rainfall will be the main storm impacts.

- Coverage of afternoon showers and thunderstorms will be slightly lower on Thursday/Friday (and mainly focused in the higher terrain of the east). However, a low-medium (20-60%) chance for diurnal convection will continue each day through Wednesday.

- NWS Heat Risk highlights Moderate (Level 2 of 4) heat impacts across the Tennessee Valley from Thursday-Wednesday. These values will increase to Major (Level 3 of 4) for parts of the area beginning Friday.

NEAR TERM

(Rest of Today and Tonight) Issued at 231 PM CDT Wed Aug 5 2026

There have been no significant changes to forecast reasoning in the near term this afternoon. Current thinking is that clusters of showers (and some thunderstorms) will continue to drift very slowly east-southeastward for the remainder of the afternoon (with coverage slightly lower across northwest AL compared to the remainder of the CWFA). Due to slow cell motions and abundant moisture in the lower troposphere, locally heavy rainfall (which may produce significant ponding of water on roads and minor flooding) will be the most significant impact, along with occasional lightning. It still appears as if convection will dissipate between 2-4Z (if not a bit earlier), with clearing skies and light SSE winds supporting the development of patchy mist/fog as temps fall into the u60s-m70s.

Previous Discussion: In the mid/upper-levels, a cutoff low (initially centered across southeastern TN) will degenerate into a highly-sheared wave extending from the central Appalachians into northern GA by 12Z Thursday. At the surface, an increasingly diffuse trough and related streamline confluence axis is predicted to remain nearly stationary from western portions of north AL/middle TN into central KY today. However, this feature will become increasingly masked tonight as SSE flow in the low-levels becomes more established due to the westward expansion of a Bermuda ridge into the southeastern CONUS and northwest Gulf Coast.

Current expectations are for ongoing shower activity across the southeastern portion of the CWFA to expand in coverage over the course of the day, with greatest spatial concentration extending from east-central AL northeastward into the central Appalachians (where lower heights aloft will provide a more favorable environment for updraft growth). Additional showers are likely to evolve in the vicinity of the remnant surface trough, with an increasing risk for thunderstorms region-wide this afternoon as temps warm into the 85-90F range (supporting MLCAPE of 1500-2000 J/kg). With steering currents weaker today and oriented from NW- to-SE, we expect very slow east-southeastward cell motions which (along with PWAT values of 1.6-1.8") will support lightning and locally heavy rainfall/minor flooding as the greatest convective impacts.

Guidance from the most recent suite of CAMs suggests that lingering weak convection will diminish earlier than yesterday evening (by 2-4Z at the latest), which appears reasonable given the reduction in low-level forcing. With light SSE flow supporting a minor increase in overnight lows (into the u60s-m70s), development of patchy fog is more uncertain, but some early morning visibility reductions may still occur in locations that experience wetting rainfall today.

SHORT TERM

(Thursday through Friday night) Issued at 1142 AM CDT Wed Aug 5 2026

Throughout the first half of the short term period (Thursday and Thursday night), a mid-level ridge will expand eastward across the TN Valley from a strong anticyclone centered across AZ/NM. Although rising heights aloft and lack of a surface boundary will provide an environment less conducive for convection, strong heating of a moist boundary layer will result in scattered afternoon showers and thunderstorms tomorrow across much of the central Gulf Coast states and southeastern CONUS, with the greatest coverage across our forecast area expected in zones of orographic lift across northeast AL/southern TN. With forecast soundings indicating similar values of CAPE/PWAT compared to today and weak/unorganized deep-layer flow, we expect similar threats for lightning and locally heavy rainfall.

Short term model consensus suggests that a gradual increase in southwesterly flow aloft will begin on Friday and continue into Friday night as a shortwave trough drops southeastward from the MO Valley into the Lower OH Valley within a broad weakness in the subtropical ridge across the central Gulf Coast. Although there is some concern that an MCV (originating from widespread convection Thursday night across eastern KS/western MO) may generate a higher coverage of afternoon showers and storms across our forecast area on Friday, this appears more likely to occur to our northwest and we will advertise POPs similar to Thursday (ranging from 10-20% west to 40-50% east). A few showers and thunderstorms may also continue on Friday night/early Saturday morning in the strengthening deep-layer warm advection regime ahead of the shortwave trough, but coverage will likely be highest to our northeast.

LONG TERM

(Saturday through Tuesday) Issued at 951 PM CDT Tue Aug 4 2026

An upper level shortwave trough looks to sweep over the Mississippi River Valley and towards the Northeastern U.S. on Saturday. By Sunday and through early next week, upper ridging is shown to build over the southern Plains and Southeastern U.S. Meanwhile, surface high pressure is expected to remain parked over the Appalachians for much of this time. This feature does shift south over the northern Gulf coast by Tuesday, however. Overall, anticipating daily chances of showers and storms, mainly during the afternoon and evening hours. Expect higher chances of showers and storms on Saturday due to the aforementioned upper shortwave trough swinging over the region, with chances decreasing for Sunday through Tuesday. PWATs will remain elevated, but bulk shear will likely be 20 knots or less throughout the period. Therefore, severe weather is not anticipated, but frequent lightning and heavy rain will be the main threats with any storms.

As for temperatures, highs in the upper 80s to lower 90s with lows in the lower to mid 70s will be common. With elevated moisture persisting, afternoon heat index values are forecast to mostly range between 98-104 degrees through the weekend, then increase a bit by early next week as rain chances decrease. This results in a Moderate HeatRisk for north Alabama and Southern Middle Tennessee this weekend, with some locations in the Major category by Monday. This will be something to watch in case Heat Advisories become necessary for all or portions of the local area. Regardless, please remember heat safety! Drink plenty of water, take frequent breaks in the shade, and never leave people or pets in vehicles!

AVIATION

(18Z TAFS) Issued at 1244 PM CDT Wed Aug 5 2026

Scattered-numerous SHRA and some TSRA will continue to impact much of north AL this aftn, with slow cell motions to the SE-ESE anticipated. Based on current radar data, we will include TEMPO groups for both HSV and MSL thru 22Z, with TSRA a greater near term concern at HSV. Aside from periods of hvy rain resulting in MVFR cig/vsby reductions, occasional lightning will be the greatest impact from this activity. Diurnal convection will likely dissipate entirely by 2-4Z (if not a bit sooner), setting the stage for development of patchy BR/FG (especially in locations that receive wetting rains today). However, with a lgt SSE flow expected to become established overnight, we will not mention vsby reductions in the forecast attm. Few-sct Cu will develop once again by the end of the TAF period, along with a light SSW wind of 5-10 kts.

HUN WATCHES/WARNINGS/ADVISORIES

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