textproduct: Huntsville

KEY MESSAGES

Updated at 242 AM CDT Thu Aug 13 2026

- The coverage of afternoon/early evening thunderstorms is expected to progressively decrease from Thursday-Sunday, but a few storms will be possible each day (especially in the east). Conditions will remain favorable for locally damaging downburst winds with this activity.

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

NEAR TERM

(Today) Issued at 242 AM CDT Thu Aug 13 2026

Showers and thunderstorms have dissipated, leaving the TN Valley with some mid to upper level cloud cover. Where there are gaps, fog will develop, however looking upstream on satellite, another batch of clouds are streaming our way. Thus, not expecting widespread fog developing. The showers and thunderstorms that were in southern IL and west KY a little while ago that were left over from an MCS have fizzled out at this hour. But will be monitoring for any of its lingering outflow boundaries to see if it regenerates any convection this morning in the TN Valley. The convection currently ongoing in southern IL is taking the same path as previous convection, sliding down the ridge, is not expected to make it this far south. If any convection is able to redevelop early this morning off those boundaries, they could be capable of producing heavy rainfall with localized flooding concerns as PWATS remain around 2", and a low risk of locally damaging downburst winds up to 60 mph with MUCAPE 1500-2000 J/kg and DCAPE 1000-1250 J/kg.

The ridge anchored across the region will strengthen further today. This will lower the POPs, but increase temps. Afternoon highs will reach the lower 90s in NE AL and the mid 90s elsewhere. With dewpoints lingering in the lower 70s, heat index values will make it feel more like it's up to 106 degrees. A Heat Advisory is in effect today through Sunday. In fact, dangerous heat will persist into next week. POPs today are only 10-20% with the greatest coverage in NE AL and Southern Middle TN as lingering boundaries could develop some storms. They too would have the potential to have localized downburst winds in any stronger storm, and heavy rainfall.

SHORT TERM

(Thursday night through Saturday night) Issued at 1114 PM CDT Wed Aug 12 2026

Short term model data continues to suggest that a strengthening subtropical high in the mid-levels will expand as it builds northward through the first half of the weekend (with the ridge likely to extend from eastern parts of the southern Plains to the southeastern Atlantic Coast by 12Z Sunday). With the building ridge expected to begin deflecting storm clusters to the north of our region as early as Thursday night, chances for showers and thunderstorms will remain rather low through the period, as broad scale subsidence and weak steering currents will dominate the local synoptic pattern. That said, intense heating along the higher terrain of northeast AL on Friday may still initiate a few afternoon thunderstorms which could produce locally damaging downburst winds given a favorable thermodynamic environment. During the timeframe from Friday night-Saturday night, there are indications that a low-amplitude easterly wave may undercut the ridge and shift westward along the northern Gulf Coast, which may also provide support for isolated thunderstorms (particularly across portions of northeast AL, where outflow from more extensive convection across north GA/central AL may enter the region).

With the general lack of cloud cover and convective impacts, afternoon temperatures will continue to rise (reaching the m-u 90s in the lower elevations both Friday and Saturday). Although there are some indications that a deeper mixing layer may lower afternoon dewpoints into the mid 60s across parts of northwest AL (especially by Saturday), heat index both days will remain in the 104-110F range (perhaps 110-112F in urban locations), and the Heat Advisory will continue through the upcoming weekend, as overnight lows in the m-u 70s will only compound impacts.

LONG TERM

(Sunday through Wednesday) Issued at 1114 PM CDT Wed Aug 12 2026

Global models continue to indicate that an intense mid-level subtropical high (initially centered across the Gulf Coast states) will retrograde westward into AZ/NM early in the extended period, as a northern stream shortwave trough digs southeastward across the Canadian Prairie. This evolution will allow WNW flow aloft of 10-20 knots to become established across the region once again by Monday, perhaps allowing a weak cold front to drop southward into the region at some point Monday night or Tuesday. Prior to the arrival of the front, very hot afternoon temperatures will exist on both Sunday and Monday, with some locations likely to reach or exceed 100F both afternoons. Although forecast soundings suggest increasingly favorable profiles for deep mixing (which could result in dewpoints perhaps mixing out into the l-m 60s across large portions of the forecast area both days), apparent temps solidly in the 105-110F range suggest that the current Heat Advisory will need to be extended into Monday.

Should the weak cold front (mentioned above) indeed enter the region on Monday night or Tuesday, it would likely be accompanied by a broken band of convection that may struggle to survive as it enters a well-mixed airmass (with lower moisture content and CAPE compared to what we are experiencing currently). However, there is a high degree of uncertainty regarding this scenario, and for this reason we will only advertise a low (10-30% POP) with afternoon temps merely dropping back into the l-m 90s.

AVIATION

(06Z TAFS) Issued at 1244 AM CDT Thu Aug 13 2026

After an increase in TSRA near a lingering outflow boundary yesterday evening, it now appears as if convection is diminishing in both coverage and intensity. However, based on current radar data, we will include a 2-hr TEMPO group for MVFR vsby reductions in SHRA at HSV, followed by a separate TEMPO group at both terminals from 9-13Z (for MVFR vsby reductions in BR/FG). SW flow will increase to 5-10 kts once again by 15Z, with development of a scattered Cu field expected around this time, as well. Although a few storms may occur in our general region once again during the mid-late aftn hours, the threat for impacts at the terminals is too low to mention in the forecast attm. Skies will become mostly clear this evening, with a lgt WSW flow continuing thru 6Z Friday.

CLIMATE

Issued at 157 PM CDT Wed Aug 12 2026

The Climate Prediction Center has included much of northern Alabama in a High Risk for Much Above Normal Temperatures and much of southern middle Tennessee and far northeast Alabama in a Moderate Risk for Much Above Normal Temperatures on August 20th and 21st.

All of northern Alabama and southern middle Tennessee is also included in a Moderate Risk for Much Above Normal Temperatures August 22nd and 23rd.

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 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.