textproduct: Huntsville

KEY MESSAGES

Updated at 1045 AM CDT Sat Sep 19 2026

- Conditions will be favorable for strong-severe thunderstorms each afternoon Today-Tuesday, with the greatest spatial coverage of storms expected Monday and Tuesday. Locally damaging downburst winds, frequent lightning and heavy rainfall will be the main storm impacts.

- Hot temperatures will continue from Today-Monday, with highs in the mid-upper 90s in the valley. A Heat Advisory remains in effect through 8 PM CDT today.

- A slightly cooler and drier airmass will arrive late in the forecast period, with highs dropping back into the 80s on Thursday/Friday.

NEAR TERM

(Rest of Today and Tonight) Issued at 1045 AM CDT Sat Sep 19 2026

A number of changes were noted with the upper level pattern in comparison to earlier this week. A former "mega" upper ridge that helped bring the heat to much of the central, southern, and eastern Lower-48 has weakened with maximum 500mb heights around 593 decameters over the AR-LA-TX-OK region. A TUTT type upper low was moving westward across the far NE Gulf of America. This Tropical Upper Tropospheric Trough feature should remain over the eastern Gulf into early next week. A weaker upper disturbance over eastern Kentucky was producing weak troughing extending southward along the AL/GA border. Otherwise, mainly sunny skies prevailed at 10 AM with temperatures climbing through the 80s with light winds.

Strong daytime heating and resultant instability will result in scattered to at times broken fields of CU and some TCU. Moderately high precipitable water of amounts from 1.6-1.8" with heating will result in most unstable CAPES rising 1500-2200 J/kg late this morning and early this afternoon. Thus low/medium chances of showers and thunderstorm will be realized mainly in the afternoon. Per convective outlooks from the SPC; some of the storms over our more eastern areas could become strong to severe. The main threat from the stronger storms will be downburst-type outflow wind gusts. The best chances for the stronger storms will be more to our east. WINDEX numbers and an inverted-V signature from forecast soundings confirm a strong outflow wind potential.

Heat is another concern for today. Before showers commence, expect another hot day with highs rising into the mid/upper 90s, with a 100 degree reading over NW Alabama. Over the past few days, strong surface heating has mixed dewpoints from the 70s into the 60s, which has put a damper on heat indexes rising into the advisory area. Unless newer guidance suggests otherwise, we are planning to let the Heat Advisory expire at 8 PM this evening. After shower activity ends this evening, expect another muggy night with lows from near 70 east to the low/mid 70s near large bodies of water. As we go to the end of the summer season, longer nights under mostly clear skies could allow the development of fog before daybreak Sunday, and mainly in/near areas that receive wetting (greater than 1/10") rainfall and/or in fog favored areas.

SHORT TERM

(Sunday through Tuesday) Issued at 1045 AM CDT Sat Sep 19 2026

The upper disturbance to our NE will move further to the east on Sun, while the upper ridge to our west and low over the NE Gulf remains. Thus another hot day expected. Highs should rise into the low 90s east to mid/upper 90s west. Dewpoints in the 70s again should mix down into the 60s, thus are expecting heat indexes to remain less than 105 degrees. Despite no advisory, area residents should maintain awareness for the heat. The mixing should also lower shower/thunderstorm chances in the afternoon. Will keep low chances of afternoon convection for our more eastern areas, that will be helped by more rugged terrain. Similarly mild/warm Sun night with lows in the low/mid 70s.

A synoptic scale system forming to our west will approach the Tennessee Valley on Monday. This system will bring low/medium chances of showers/thunderstorms. With better forcing from this system, storms that form could become strong to severe, with more downburst-type outflow wind gusts the main threat. This risk has been noted by the SPC, with most of the area in a Marginal (1 out of 5) Risk for severe storms. Before showers begin, expect similarly hot conditions with highs mainly in the 90s (lower 90s east to mid/upper 90s west). It should be bit cooler Mon night with lows from the mid 60s east to lower 70s near large bodies of water. Scattered to numerous showers and thunderstorms are forecast Tuesday, with highs from the upper 80s east to mid 90s west. Confidence is too low this far out to exactly discern storm strength; cannot rule out stronger storm chances Tue. Lastly, the Autumn 2026 season begins Tue evening around 704 PM CDT.

LONG TERM

(Tuesday through Friday) Issued at 1057 PM CDT Fri Sep 18 2026

Latest extended range forecast data suggest that a weak northern stream trough will advance slowly eastward from the Mid-MS Valley into the northern Mid-Atlantic states next week, as it will likely be blocked by ridging to its north. At the surface, a trough (initially extending from central parts of MS/AL north- northeastward into the Upper OH Valley) is predicted to remain nearly stationary on Tuesday, and will likely focus development of additional showers and thunderstorms across our region both during the day and at night. In similar fashion to Monday, a few strong-severe thunderstorms may occur during the afternoon and evening hours, aided by high CAPE and increasing W-NW flow aloft.

Although there is some uncertainty regarding precisely when this will occur, the surface trough is expected to shift slowly southeastward at some point Wednesday/Thursday, allowing a cooler/drier airmass (originating from an anticyclone across southern QC) to spread southeastward into the region. This coupled with 20-30 knot W-NW flow aloft and dry advection through the depth of the tropospheric column will allow rain chances to decrease considerably on Thursday/Friday. Afternoon highs will fall back into the l-m 80s by the end of the work week, with overnight lows Thursday night/Friday morning in the u50s-l60s.

AVIATION

(12Z TAFS) Issued at 617 AM CDT Sat Sep 19 2026

Low chances of showers and thunderstorms this afternoon around 19-01Z at both terminals. Storms will be capable of producing lightning and strong to damaging wind gusts, along with a VIS reduction to MVFR.

HUN WATCHES/WARNINGS/ADVISORIES

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

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