Area Forecast Discussion

KEY MESSAGES

Updated at 142 PM CDT Sat Sep 19 2026

- Conditions will be favorable for strong-severe thunderstorms each afternoon into 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 into Monday, with highs in the mid-upper 90s in the valley. A Heat Advisory remains in effect through 8 PM CDT this evening.

- 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

(Tonight) Issued at 142 PM CDT Sat Sep 19 2026

As of the early afternoon, strong heating and steeper mid-level lapse rates have resulted in scattered shower and thunderstorm development over and around the Tennessee Valley. Movement of the activity is SSE around 5 mph. There should be a somewhat higher coverage of showers, with some of the storms especially east of I-65 could become strong to severe. Downburst/microburst type outflow wind gusts and heavy downpours are the main threats.

Mixing now occurring was reducing most area dewpoints into the mid/upper 60s. This has helped relieve most of the area from experiencing heat indexes at or above 105. Thus we will let the on-going heat advisory expire at 8 PM this evening.

Otherwise, shower activity should end as we go into the early evening. Depending upon where and how much rain falls, patchy late night fog development could occur. Areas that receive a "wetting" rain of over 1/10 of an inch, as well as those more sheltered valley locations would have the best odds of experiencing fog. Low temperatures should cool from the upper 60s NE Alabama to the low/mid 70s urban areas and locations near large bodies of water.

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 night 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

(18Z TAFS) Issued at 1228 PM CDT Sat Sep 19 2026

Strong daytime heating and resultant instability has resulted in the development of isolated to scattered showers and thunderstorms around the TN Valley. Most of this activity was forming in the higher terrain. General movement of the convection was SSE around 5kt. Given development trends, have kept a PROB30 in for both terminals this afternoon and early evening. Storms will be capable of producing strong to severe microburst type wind gusts and heavy downpours, with brief reductions of CIG/VSBY to MVFR and lower. Convection should wane as we go into the evening with VFR weather returning. However late in the night and early Sun morning, cannot rule out patchy fog. It will be more likely in/near places that received recent heavy rainfall.

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.