textproduct: Huntsville

KEY MESSAGES

Updated at 429 AM CDT Fri Aug 14 2026

- A Heat Advisory remains in effect for the entire forecast area through Sunday, with extensions likely into the middle of next week.

- There will be low (10-30%) chances for a few thunderstorms this afternoon. A couple of storms may become strong with strong winds, frequent lightning and heavy rainfall the main impacts.

NEAR TERM

(Today) Issued at 429 AM CDT Fri Aug 14 2026

Strong upper level ridging with maximum 500mb heights near 595 decameters over the Deep South was helping to bring very warm to hot conditions over and around the Tennessee Valley. This upper ridge should amplify even more, nearing 600 decameter heights over the weekend and early next week. The upper high, along with surface high pressure in place off of the east coast, should keep a mainly S-SW flow across the area. This flow will bring moisture from the Gulf of America across the Tennessee Valley, producing dewpoints in the low/mid 70s. Strong daytime heating of the airmass will result in high temperatures soaring into the mid/upper 90s. These 70s dewpoints will produce Heat Index values from 100 to 108 degrees over much of the area. Thus a Heat Advisory will continue across the area. Some of the models are showing some mixing this afternoon, which could lower dewpoints and maximum heat indices.

Deeper moisture more to the east, plus strong heating and resultant higher instability could result in isolated to scattered shower and thunderstorm development this afternoon. With surface based CAPES rising higher than 2000 J/kg, strong outflow wind gusts and heavy downpours are the main threats, along with cloud to ground lightning strikes.

SHORT TERM

(Tonight through Sunday night) Issued at 1007 PM CDT Thu Aug 13 2026

There is expected to be no change in the either the intensity or position of a strong 500-mb ridge encompassing much of the south- central and southeastern CONUS on Friday night or Saturday. Thus, even with a few afternoon showers and thunderstorms potentially lingering for a couple of hours beyond 0Z Saturday (particularly across northeastern parts of the forecast area), dry but warm/muggy conditions appear likely to exist for much of the night. There are still indications that the northern portion of an easterly wave (tracking across FL and into the eastern Gulf) may induce a greater spatial coverage of seabreeze and outflow- driven convection on Saturday from the central Gulf Coast northeastward into SC, which could potentially generate a few storms in northeast AL as well. Should this occur, it would likely be late in the afternoon, with a similar risk for damaging downburst winds and frequent lightning compared to previous days.

During the timeframe from Saturday night-Sunday night, the center of the intense subtropical high aloft will slowly migrate westward (becoming positioned across north-central TX by 12Z Monday). Although this evolution will gradually reduce the impacts from deep-layer subsidence and allow for a minor increase in WNW flow aloft by late Sunday/Sunday night, efficient mixing and drying of the boundary layer will actually lower CAPE as PWAT values fall into the 1.3-1.5" range. Thus, we expect dry conditions to prevail during this period with very hot afternoon temperatures in the 95-100F range both Saturday and Sunday. If dewpoints indeed mix out into the l-m 60s (potentially u50s) across western parts of the forecast area on Saturday and region- wide on Sunday, this will certainly have a favorable impact on both afternoon heat index and overnight low temps (mainly in rural locations). However, this trend has not yet been captured by blended model guidance, and with apparent temps still expected to reach 105-110F, a Heat Advisory will remain in effect through the weekend.

LONG TERM

(Monday through Thursday) Issued at 1007 PM CDT Thu Aug 13 2026

The 5h ridge will remain in place across the southern U.S. next week, with west-northwest flow across the central Plains into the OH and TN valleys. The question is how amplified and it's eastward influence into the TN Valley and southeast U.S. The ECMWF is a bit more amplified with the ridge in the Rockies and Plains which could inflate convective chances and some heat relief at times due to a more northwesterly flow if this verifies. For now, forecast highs in the middle to upper 90s on Monday may drop into the lower to middle 90s in valley areas Tuesday through Thursday (upper 80s to around 90 atop the higher Cumberland Plateau areas). Overnight lows in the middle to upper 70s will dip into lower to middle 70s. For now, PoPs remain low on a day to day basis next week, but this certainly could waiver upward depending on the evolution of the ridge and northwesterly flow/MCS cluster tracks around the periphery of the ridge.

AVIATION

(12Z TAFS) Issued at 625 AM CDT Fri Aug 14 2026

For most of the area, VFR conditions prevailed over the TN Valley at TAF issuance. Patchy fog that formed in a few sheltered valleys should dissipate this morning, as daytime heating and stronger mixing resumes. Higher moisture content near and east of the I-65 corridor, plus strong daytime heating could result in isolated to scattered shower/thunderstorm development this afternoon. Storms that form could produce strong outflow winds and heavy downpours, producing brief CIG/VSBY reductions. Light winds early will become westerly around 5kt in the late morning and afternoon. Winds will become light/variable again this evening.

CLIMATE

Issued at 429 AM CDT Fri Aug 14 2026

The Climate Prediction Center has included the Tennessee Valley in a Moderate Risk for Much Above Normal Temperatures from August 21th through August 23rd.

There is a 40-60% chance for temperatures above 95 to 97 degrees (F) and heat index values above 105 to 110 degrees (F) during this period.

More information on the CPC U.S. Hazards Outlook can be found at:

https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php

HUN WATCHES/WARNINGS/ADVISORIES

AL...Heat Advisory until 7 PM CDT Sunday for ALZ001>010-016.

TN...Heat Advisory until 7 PM CDT Sunday for TNZ076-096-097.