textproduct: Huntsville

KEY MESSAGES

Issued at 747 PM CDT Wed May 20 2026

- Medium to high chances (60-90%) of showers and thunderstorms are forecast at times through early next week.

- Locally heavy downpours and lightning will be the primary hazards, but brief gusty winds will also occur with the stronger thunderstorms.

NEAR TERM

(Rest of tonight and Thursday) Issued at 754 PM CDT Wed May 20 2026

Mini-supercells with weak rotation have developed in southern TN and north central/northeast AL this morning. A couple have produced small hail and heavy downpours. A mesoscale vorticity center has moved into a low level CAPE rich environment which may have aided in the rotation to develop. These cells will continue to thrive until loss of heating starts to deplete their updrafts. However, we will maintain low to medium chances of additional showers and thunderstorms overnight as clusters in central and south AL lift northward producing outflow into untapped unstable air. Patchy fog can't be ruled out, but low clouds will tend to develop in the moist southerly flow environment just above the surface. Another shortwave/mesoscale convective vorticity center now along the LA Gulf Coast will lift northeast into the TN Valley Thursday morning. This will produce additional clusters of showers and thunderstorms through the midday into the early afternoon hours. The main hazards will be lightning, heavy downpours and perhaps brief gusty winds. The clouds and precipitation will keep highs in the upper 70s to lower 80s.

SHORT TERM

(Thursday night through Saturday) Issued at 754 PM CDT Wed May 20 2026

A similar pattern will remain in place through Saturday with additional shortwaves arriving Thursday night into early Friday, and again Friday night into early Saturday. These waves may have stronger low to mid level flow of 30-40kt at times, which may amplify the risk of gusty winds with the stronger storms. Lower PWs and drier air may follow behind the wave Saturday morning, but the blend of models still includes medium to high PoPs through the afternoon as well. This is something we may need to modify in future forecasts. High temperatures will remain in the upper 70s to lower 80s with lows in the lower to middle 60s.

LONG TERM

(Saturday night through Wednesday) Issued at 754 PM CDT Wed May 20 2026

A fairly stagnant weather pattern will remain in place late this weekend into the middle of next week. A 5h ridge will be anchored over the southwest Atlantic into GA and FL northwest into the Upper MS valley as a cutoff low in the southern Plains slowly moves northward through the week. The medium range models shows a similar low developing over the southern Plains by mid to late week. However, there is disagreement in the ridge position, the ECMWF is favored here due to its persistence this week. In either case, the pattern will keep persistent deep layer southerly flow in play for the TN valley during this period. This results in medium to high chances of showers and a few thunderstorms will persist Sunday and Monday lowering to low to medium Tuesday and Wednesday, with greatest PoPs during the daytime heating hours into the early evening.

AVIATION

(00Z TAFS) Issued at 450 PM CDT Wed May 20 2026

A low to medium chance of SHRA and perhaps a TSRA continue tonight into Thursday. However, confidence in timing and location remain uncertain, so have opted to keep VCSH at both KHSV and KMSL for now, but amendments may be necessary. Lower ceilings below 010agl (IFR) are forecast to develop by 08Z, and rise into the 010-025agl range (MVFR) by 15Z, then reach above 030agl (VFR) by NLT 20Z. Prevailing wind will be light and variable tonight, then become southerly at 6kt or less after 15Z.

HUN WATCHES/WARNINGS/ADVISORIES

AL...None. TN...None.