textproduct: Huntsville

KEY MESSAGES

Updated at 1018 AM CDT Sat Sep 5 2026

- A Heat Advisory remains in effect through 8 PM Sunday due to Major to Extreme HeatRisk, along with afternoon heat indices rising up to 105-109 degrees in portions of the forecast area.

- A low chance (30% or less) of thunderstorms are forecast this afternoon into the late evening, with a low chance of some becoming strong to severe. Damaging winds are the primary threat.

NEAR TERM

(Tonight) Issued at 255 PM CDT Sat Sep 5 2026

No changes were needed to the forecast at this time. We are monitoring a large outflow boundary (and subsequent outflows from storms that have developed from it) to our northeast. This activity has a history of producing strong to severe storms near Knoxville. We have also seen small showers develop a couple counties to our NW as well as to our south. Development over NE AL, southern middle TN, and into north-central AL is expected within an hour or so. Damaging downburst winds, frequent lightning, and heavy downpours remain the main threats. Stay weather aware and have multiple ways of receiving warnings should one be issued for your area!

Additionally, temperatures have risen into the mid 90s for most locations with dew points in the lower to mid 70s. This has resulted in heat indices in the 103-108 range so far this afternoon. Make sure to drink plenty of water and take frequent breaks in the shade!

Previous Discussion:

The upper ridge will be pushed back west today as an upper trough digs over the eastern seaboard into the Southeast. In addition, surface high pressure over the Appalachians will shift south as a backdoor cold front sweeps into and over the Ohio and Tennessee valleys. Even so, for any storms today, the main lifting mechanism will be remnant outflows over the region helping create a domino effect of convective initiation. Instability will be abundant, with minimal bulk shear. Looking at parameters conducive for downbursts such as WINDEX, DCAPE, theta-e difference, and lapse rates, all thresholds are met by various guidance for strong to severe downbursts.

With DCAPE exceeding 1000 J/kg, damaging winds will be the main threat, along with frequent lightning and brief, heavy downpours (due to 1.7-2.0 inch PWATs). Observed soundings show a freezing level around 15.5 kft at BMX and around 14 kft at BNA. Model soundings for the afternoon show freezing levels around 15.5 kft as well; therefore, not anticipating much in the way of hail with the storm activity today. With LCL heights above 1000 m, not expecting a tornado threat either. This concurs with SPC's Marginal Risk of severe weather over a portion of the local area (generally east of I-65) along with only damaging winds being outlooked (versus any hail or tornado threat). Overall, expect a low chance (20-30%) of "pop up" thunderstorms to occur generally between 3-10 PM this afternoon/evening, especially over portions of north-central AL, NE AL, and into southern middle TN. Stay weather aware in case any warnings are issued for your area! When thunder roars, go indoors! See a flash, dash inside!

Even with thunderstorm activity, it will still be very hot. Temperatures are forecast to reach the mid to upper 90s before storms really begin to form. This, in addition to dew points in the lower to mid 70s will result in expected heat index values between 105-109 degrees. Furthermore, WBGTs this afternoon rise into the upper 80s to around 90 degrees and NWS HeatRisk is slated to be in the Major to Extreme categories (levels 3 and 4 of 4). The Heat Advisory therefore remains in effect for all of north Alabama and southern middle Tennessee through 8 PM Sunday evening. Please exercise heat safety, especially if working outside or if you have outdoor activities! Stay hydrated, wear loose-fitting and light colored clothing, take frequent breaks in the shade and/or AC, and never leave people or pets in vehicles!

Not much relief will be felt tonight as lows merely dip into the lower to mid 70s. While a low chance of some patchy fog exists (especially in river valleys, near bodies of water, and where rain falls today), not expecting this to be widespread at this time.

SHORT TERM

(Sunday through Monday) Issued at 1018 AM CDT Sat Sep 5 2026

Northwest flow then sets up aloft on Sunday as the upper ridge begins to slowly push eastward once again. The aforementioned backdoor cold front is slated to traverse the Tennessee Valley during the afternoon. However, there is some uncertainty in the timing of this front through the region. A quicker passage would result in slightly cooler temperatures, but more importantly lower dew points as drier air is ushered into the region. Most guidance that agrees with this scenario suggest dew points falling into the 60s, with others hinting at upper 50s for some areas. However, if this front is slower to move through the area (which has seemed to be the trend the past couple of days), dew points will continue to be higher (in the lower to mid 70s) with highs in the mid to upper 90s once again. This would result in heat indices reaching between 102-109 degrees, NWS HeatRisk mostly in the Major category (level 3 of 4), and WBGTs in the upper 80s to around 90 degrees.

Current thinking is that the front is likely to be slower, so the Heat Advisory was extended in a previous update through 8 PM Sunday evening. This will be monitored through the weekend; but, please remain weather aware. Drink plenty of water and take frequent breaks in the shade! As for any thunderstorm activity, chances are very low (less than 10%) and would be most likely caused by orographic mechanisms in the higher terrain of NE AL and into southern middle TN Sunday afternoon. Any activity will quickly taper out in the early evening, with lows in the upper 60s to lower 70s.

For Monday, the slightly drier and cooler air filtered into the region will result in forecast highs in the upper 80s to lower 90s east of I-65 and in the lower to mid 90s west of I-65. There is a low chance (15-30%) of pop up showers/storms again Monday afternoon, but this will likely be concentrated over NE AL and portions of southern middle TN due to terrain influences.

LONG TERM

(Monday night through Friday) Issued at 937 PM CDT Fri Sep 4 2026

Heat will persist through the long term as well. The vast ridge of high pressure that is centered over the Southern Plains and Mid MS Valley will expand eastward to encompass the rest of the Southeast early this week. Mid week, a trough will swing through the southern Canadian prairie provinces dampening the ridge, and sfc high pressure will set up along the Appalachians. This set up could create a CAD expanding into NE AL and portions of Southern Middle TN. If this comes to fruition, adjustments to POPs (slight increase) and temps (slight decrease) would be needed. Regardless, it looks like temps will remain in the 90s throughout the week, which is par for the course this month, but running a tad higher than seasonal norms which is 87-88 degrees. Heat index values will hover around 100 degrees and the NWS Heat Risk will be a level 2 (Moderate Level) for the large majority of us. Remain heat smart: slow down, cool down, stay hydrated and NEVER leave people or pets in vehicles.

AVIATION

(18Z TAFS) Issued at 1155 AM CDT Sat Sep 5 2026

VFR conditions will largely prevail at the terminals through at least this evening. The exception will be if showers/storms (20-30% chance) move over the TAF sites at points during this time and bring lower VIS, CIGs, as well as gusty winds, frequent lightning, and heavy downpours. Most of the shower and storm activity is expected to wane by mid to late evening. Elevated moisture, along with light to calm winds and clearing clouds may result in conducive conditions for at least patchy fog development by daybreak. Only included this potential at HSV for now, but this will be monitored. Any fog will lift and dissipate with the sunrise Sunday morning. Expect northerly winds and mostly clear skies by the late morning/early afternoon on Sunday.

HUN WATCHES/WARNINGS/ADVISORIES

AL...Heat Advisory until 8 PM CDT Sunday for ALZ001>010-016.

TN...Heat Advisory until 8 PM CDT Sunday for TNZ076-096-097.