textproduct: Huntsville

KEY MESSAGES

Updated at 1132 AM CDT Wed Aug 12 2026

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

- A low conditional threat for strong to severe storms will exist once again this afternoon.

NEAR TERM

(Rest of Today and Tonight) Issued at 832 AM CDT Wed Aug 12 2026

Tranquil conditions across the Tennessee Valley this morning (other than some very localized valley fog in northeast Alabama). This fog will dissipate quickly this morning, with mostly clear conditions allowing for intense heating this morning, warming temperatures into the low to mid 90s by the afternoon. Combined with dewpoints in the mid to perhaps upper 70s, this will push heat index values at or in excess of 105 degrees by the afternoon hours. This combined with a NWS Heat Risk of Major impact (Level 3/4) and wet-bulb globe temperatures in the 85-90 degrees will create dangerous heat conditions across the Tennessee Valley today. A Heat Advisory will be in effect beginning at 1 PM this afternoon for the entire region.

Coupled with the heat threat will be another conditional, low threat for severe thunderstorms during the mid/late this afternoon. CAMs continue to be all over the place and have struggled with the timing of diurnal convection over our area and location of mesoscale boundaries upstream. What we can say is that there is a low chance (20-30%) of showers/storms this afternoon due to diurnal heating (likely 2 to 8 PM). While most locations will remain dry a few storms will develop and we'll have the environment for them to become severe, with damaging winds and heavy rainfall the main threat. Tonight, we'll again need to watch convection upstream over the Ohio Valley. If it holds together (and that's a big if), steering flow could take a few clusters of elevated, subsevere storms through the area late this evening an/or overnight (similar to last night). None of the 06z/12z Hi- Res guidance really supports this, but a current glance at the location of storms over Indiana/Kentucky and the position of synoptic features, suggest the trajectory of this convection may eventually drop south and at least brush our area. Thus, will leave a low chance for showers overnight, especially in the eastern half of our area.

SHORT TERM

(Thursday through Friday night) Issued at 832 AM CDT Wed Aug 12 2026

A large area of high pressure will build into the Tennessee Valley from the west late this week, with a heat dome underneath this ridge subsequently shifting east into the region. Ample sunshine will warm temperatures will the mid to upper 90s and combine with dewpoints in the mid to upper 70s will create dangerous heat indices in the 105-110 degree range. NWS Heat Risk highlights a Major Risk (Level 3/4) of heat related impacts during the day (and overnight as lows will remain in the mid to upper 70s). Thus, a Heat Advisory is in effect for this entire period and will likely need to be expanded through the weekend. Another low chance (20-30%) of showers and storms is forecast again Thursday afternoon, but by Friday strong subsidence from the ridge should prevent any pulse convection from forming and PoPs will drop to below 10%.

LONG TERM

(Saturday through Tuesday) Issued at 1045 PM CDT Tue Aug 11 2026

Extended range data from the latest suite of global models is in general agreement that a subtropical high (centered from the Lower MS Valley to the southeastern Atlantic Coast) will continue to strengthen this weekend, with geopotential heights perhaps reaching 600 dam. Thus, excessive heat will continue to be a concern across the TN Valley, with highs remaining in the m-u 90s from Saturday-Monday (and perhaps exceeding 100F in several locations on both Sunday and Monday afternoons). Although a few afternoon storms may occur on both Saturday and Sunday (primarily in the higher terrain of northeast AL), rain chances will remain low and there is a very high chance that the pre-existing Heat Advisory will need to be extended through Monday, perhaps with an upgrade to an Extreme Heat Warning due to Heat Index readings surpassing 110F. By late in the forecast period, there are indications that the subtropical high may begin to retrograde into the southern High Plains, perhaps allowing NW flow aloft to become reestablished across our region by Monday/Tuesday. Should this occur, a weak cold front may bring a broken line of showers and thunderstorms to the region Monday evening, followed by a slight drop in temperatures/dewpoints on Tuesday.

AVIATION

(18Z TAFS) Issued at 1132 AM CDT Wed Aug 12 2026

VFR conditions will be the predominant flight category at each terminal through the period. A low chance for a TSRA is forecast between 20-00z and have handled this with a PROB group. Should a storm impact either terminal, localized MVFR conditions due to reduced visibilities and ceilings may occur and AWWs will be needed.

CLIMATE

Issued at 301 AM CDT Tue Aug 11 2026

The Climate Prediction Center has included the whole area in a Moderate to a High Risk for Much Above Normal Temperatures for August 18th through August 22nd. The High Risk includes locations south of a line from Lexington, to Athens, New Hope and Fort Payne. The Moderate Risk include locations north of that line. Therefore, there is a 40-60% chance in the Moderate Risk locations and a 60-80% chance for those in the High Risk areas for temperatures above 95-97 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.