Marine Weather and Tide Forecast for Holiday Shores, IL

SHORT TERM
(Through Late Thursday Night)
Issued at 247 PM CDT Wed Jun 10 2026

An active 48 hours of weather is in store for the region, with multiple opportunities for thunderstorms capable of damaging winds, flash flooding, and even tornadoes. The first of these rounds of storms is already ongoing in northeast Missouri thanks to a passing shortwave, which triggered the development of early morning elevated storms in northwest Missouri several hours ago. These storms have steadily strengthened and moved east, and are now slowly moving through northeast Missouri and west-central Illinois as of 1:00 PM. For this initial round, the primary concern is heavy rain, although the potential for damaging downburst winds may also slowly increase as surface-based instability increases.
SPC mesoanalysis indicates that a corridor of 2-2.2 inches of precipitable water has developed along the nose of a relatively robust low level jet, and this is feeding directly into the ongoing storms. While they are steadily moving east, they are not doing so particularly quickly, and when combined with likely 1 to 2 inch per hour rain rates, localized flash flooding will be possible. Fortunately these areas have not seen quite as much rain as other areas over the past few days, but this is likely not enough of a mitigating factor to eliminate this threat.

This initial round is likely to last another couple of hours, and move east of the area by roughly 3 to 4 PM. Even if we manage to escape widespread flash flooding issues with this initial round though, it likely will act to saturate some areas in advance of the next round of thunderstorms later this evening. While these storms are acting to stabilize the lower levels in the immediate vicinity, satellite imagery reveals plenty of clearing behind this round, and mesoanalysis also indicates that a very unstable airmass (3000-3500 J/kg MLCAPE) is being quickly reinforced just to the west across northwest Missouri. This is likely due to the presence of the aforementioned low level jet, which is drawing warm and humid air quickly in to replace the shallow cold pool behind these storms. Not to mention, 2+ inch PWAT values also extend well to the west and even into far northeast Kansas, so there will be plenty of fuel for more heavy rain with the next round. As storms arrive from the west, confidence is growing that a line of storms will slowly pivot into our area and become oriented almost parallel to the mean flow, potentially leading to training cells with very heavy rain rates. This also may occur over the same areas that are seeing heavy rain now, exacerbating the threat. All told, totals of 3 to 6 inches of rain will be possible between this afternoon and early tomorrow morning, primarily across northeast Missouri and west-central Illinois. A Flash Flood Watch has been issued in these areas until 6 AM tomorrow to account for this.

Not only this, but there is also amble effective bulk shear collocated with all of this instability (40-50kt), which will also support organized convection capable of severe thunderstorm hazards.
Current shear parameters and initially clockwise-turning hodographs suggest that while supercells may develop to our west, as discussed previously these storms are very likely to grow upscale into a linear complex of storms. As such, damaging straight line winds (60- 75mph) will be the most likely (non-water) hazard in our area, although considering the 30-35kt 0-3km shear and likely presence of a lingering outflow boundary, QLCS tornadoes will be possible as well. Hail does not appear to be a significant hazard, unless a stray supercell manages to remain isolated long enough to reach our area. The most significant hazards for the second round are most likely locally between about 7 PM and 11 PM, with a gradual weakening as storms move east-southeast through the night. Storms are expected to exit the area or diminish prior to sunrise, laying down an outflow boundary somewhere across our area in the morning.
This will set the stage for tomorrow's threat, which will be discussed in more detail in the Long Term discussion below.

BRC

LONG TERM
(Friday through Next Wednesday)
Issued at 247 PM CDT Wed Jun 10 2026

In the wake of tonight's storms, persistent south-southwest return flow is likely to maintain a hot and humid airmass across our area, although the distribution of greatest instability may be impacted by outflow from morning activity if it persists later than currently expected. In the afternoon and evening, a shortwave will drive a sharp cold front southeast through Missouri and eventually Illinois, which is expected to overturn this unstable airmass and produce another round of strong to severe thunderstorms across much of the area.

While most of the early part of the day should be dry, temperatures in the low to mid 90s coupled with low to mid 70s dewpoints should yield 3000-4000+ J/kg of surface-based CAPE by mid to late afternoon. Initial storms are expected to develop along the boundary to our west in northwest Missouri during the early to mid afternoon, grow upscale into another line, and steadily move through our area during the evening hours. As it does so, damaging straight line winds appear to be the most likely hazard with these storms, followed closely by QLCS tornadoes thanks to continued southwesterly 30-40kt 0-3km shear and perhaps the presence of another lingering outflow boundary. What separates tomorrow's severe threat from tonight's is most coverage, as stronger storms are likely to spread further southeast and impact a larger portion of the forecast area.
These storms likely will also feature heavy rain rates but will be more progressive than tonight's storms, which should mitigate the threat of another round of flash flooding. The most likely window for severe hazards will be between 6 to 11 pm, although this may linger a little bit later into the night. Thunderstorms, severe or not, should exit the area to the southeast prior to sunrise.

Lastly, tomorrow is also expected to be the third day in a row featuring early season heat, with heat index values ranging from generally 95 to 105 degrees (highest in the St. Louis metro area).
This still falls just a bit short of Heat Advisory levels, but may cause problems for those sensitive to heat or otherwise unprepared for these conditions this early in the season.

While Friday will feature largely dry conditions and milder temperatures in the wake of the passing cold front, an active, quasi- zonal flow regime will maintain an active pattern over the weekend and potentially into next week. In particular, Saturday may see another round of strong to severe thunderstorms, although with multiple rounds of strong to severe storms just over the next 24-36 hours, most forecast attention was given to the shorter-term hazards for this forecast package.

BRC

AVIATION
(For the 00z TAFs through 00z Thursday Evening)
Issued at 620 PM CDT Wed Jun 10 2026

Showers and thunderstorms, some strong to severe, will move toward UIN through 03Z bringing MVFR/IFR ceilings and visibilities in heavy downpours along with the potential for hail and wind gusts over 35 knots. These storms will move south affecting COU/JEF between 04-08Z and the St. Louis area terminals between 05-08Z, though they are expected to lose some of their intensity as they move to the southeast. Additional thunderstorms are expected to develop on Thursday afternoon and evening along a cold front which will affect UIN/COU/JEF during the afternoon, and the St. Louis area terminals after 00Z. These storms will likely also have the potential to produce MVFR or possible IFR ceilings and visibilities in heavy downpours in addition to hail and strong wind gusts. Winds will gust into the 25 to 30 knot range on Thursday afternoon outside of thunderstorms.

Britt

LSX WATCHES/WARNINGS/ADVISORIES
MO...Flood Watch through Thursday morning for Knox MO-Lewis MO-Marion MO-Shelby MO.

IL...Flood Watch through Thursday morning for Adams IL-Brown IL-Pike IL.