Marine Weather and Tide Forecast for Huey, IL

SHORT TERM /THROUGH THURSDAY/
Issued at 251 AM CDT Wed Aug 5 2026

Regional radar imagery shows the remnants of a small MCV moving east across west-central Illinois early this morning. Further upstream, more widespread elevated convection exits across eastern Nebraska and western Iowa along and poleward of a slow- moving cold front. This boundary is expected to ooze southward during the day today, and weak low-level convergence in the vicinity of the boundary and a subtle midlevel shortwave trough should provide enough large-scale ascent for scattered to widespread showers and thunderstorms to enter northeast Missouri and west-central Illinois near or just after midday. The earlier arrival of showers and storms (or at least thicker mid/high level clouds) casts doubts on instability and severe potential across these areas later today. In fact, the 0Z HRRR has the highest probabilities for at least 1000 J/kg of SBCAPE and 30+ knots of deep-layer shear at around 50% in central Missouri late this afternoon. Essentially, there is likely to be a spatial gap between the higher shear (farther north) and the higher instability (farther south). That being said, a few strong to severe storms cannot be ruled out from late this afternoon through early/mid evening with damaging winds the main threat.

The focus then shifts to the threat for heavy rainfall and flash flooding beginning late this evening as a 30+ knot low-level jet strengthens. The v component (north-south) is quite strong, above the 90th percentile of climatology. This jet also veers more westerly and becomes more parallel to the surface cold front, which suggests training is possible. CAMs all have at least some training late tonight into early Thursday morning, but exactly where is uncertain. My best guess is near to just north of the I-70 corridor, but it will depend on exactly where the front is located tonight.
The possibility of training thunderstorms in an environment characterized by deep warm cloud depths and anomalously high precipitable water values (~2.0", >95th percentile) suggest high rainfall totals and an increasing potential for flash flooding.
The LPMM of the HRRR has pockets of 2-4", with the REFS in the 3-5+" range. Given the pattern and the environment described above, I would not be surprised to see a narrow west/northwest to east/southeast axis where 3-5+" occurs, with locally higher totals not out of the realm of possibility. Given this increased threat, have issued a flash flood watch from 10 PM tonight through 10 AM Thursday morning. The area was extended spatially a bit farther both to the north and south due to the uncertainty in the exact location of the front tonight.

Low-level moisture convergence weakens and shifts southeastward on Thursday morning. Mid/upper level heights also rise behind a departing midlevel shortwave trough. This should mean an end of the flash flood threat and a lot of dry time from late morning into the early afternoon hours. Isolated showers/thunderstorms may redevelop Thursday afternoon in the vicinity of the front, but this could be south of the area as morning convection may produce outflow and move the effective front more equatorward.

LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/
Issued at 251 AM CDT Wed Aug 5 2026

(Thursday Night - Friday Night)

There looks to be two additional rounds of widespread showers and thunderstorms, one Thursday night and another Friday night. For Thursday night, the focus should shift southward, more toward southeast Missouri and southwest Illinois. This is where most guidance favors the stronger low-level moisture convergence.
Training may be a concern again with a veering low-level jet more parallel to the quasi-stationary front. A couple of factors though suggest the flash flood threat probably will be lower: 1)
precipitable water values are not as high, closer to 1.8" (near or just below 90th percentile), and 2) locations favored for storms Thursday night are farther south than tonight.

The approach of a midlevel shortwave trough Friday evening and an increasing low-level jet should mean another round of nocturnal convection Friday night. This round probably will shift back north, and may occur in areas that get significant rainfall tonight into Thursday morning. If this is indeed the case, that could mean a renewed flash flood threat. However, the jet itself looks weaker than either tonight or Thursday night and the rainfall does not look as efficient either with lower warm cloud depths and precipitable water values.

(Saturday - Monday Night)

Guidance is in pretty good agreement that the quasi-stationary front will move northward on Saturday as a warm front. After this front moves through, the chances for any showers and storms ceases. The pattern quickly though shifts to heat and humidity as both temperatures and dewpoints increase from southwest to northeast.
Saturday may be a bit of a transition day, with highs approaching 90 degrees and peak heat index values likely around the century mark. Sunday and Monday look hot and humid areawide with highs in the low to mid 90s and widespread 100-105 heat index values. Some areas may see 105+F heat index values, which is magnitude heat advisory criteria.

(Tuesday - Wednesday)

Ensemble guidance suggests a midlevel trough will dig into the Great Lakes early/mid next week, with the ridge shifting more toward the desert southwest. There is quite a bit of spread however with the trough across the Great Lakes. Roughly half of members from the LREF are weaker with this feature, with a surface cold front possibly not making it into our area. The other half has a stronger trough, with a cold frontal passage across the area sometime Tuesday/Tuesday night. This latter scenario would end the heat/humidity, whereas the first scenario likely would continue the 100-105+ heat index values each afternoon.

AVIATION /18Z TAFS THROUGH 00Z FRIDAY/
Issued at 1238 PM CDT Wed Aug 5 2026

Morning showers and thunderstorms will continue to weaken and dissipate across central MO, persisting longer across northeastern MO/west-central IL, impacting KUIN at times. Additional development of showers and thunderstorms will occur late this afternoon/evening, increasing in coverage tonight. All terminals are forecast to be impacted for at least a few hours, but showers and thunderstorms may tend to shift south of KUIN with time. Showers and thunderstorms will be capable of MVFR to IFR flight conditions, heavy rainfall, and gusty winds. It is still uncertain where the strongest and most persistent thunderstorms will occur. Precipitation will gradually come to an end Thursday morning, but lower ceilings could linger beyond that time, especially at KUIN.

The chances of additional shower and thunderstorm development increase along/south of I-70 Thursday evening, but chances remain low through the end of the TAF period.

LSX WATCHES/WARNINGS/ADVISORIES
MO...Flood Watch from 10 PM CDT this evening through Thursday morning for MOZ018-019-026-027-034>036-041-042-047>052- 059>065-072-073.
IL...Flood Watch from 10 PM CDT this evening through Thursday morning for ILZ095>098.