Marine Weather and Tide Forecast for Holiday Shores, IL

SHORT TERM
(Through Late Thursday Afternoon)
Issued at 215 AM CDT Wed Jun 24 2026

With a surface ridge axis to our east centered north of the Ohio River Valley, weak return flow is bolstering temperatures and dew points across the region. To our north associated with a mid-level shortwave tracking through the northern CONUS, a meager cold front is forcing scattered convection across the Upper Mississippi River Valley. This front will continue to make southward progress overnight and, by most short-range guidance depictions, arrive in northern Missouri later this morning. High-resolution guidance continues to depict surface dewpoints pooling ahead of the front which, combined with meager yet sufficient low-level forcing and negligible upper-level ascent, will result in scattered weak convection across most of the region. While most of the region will be under some threat for thunderstorms, there will likely be plenty of dry time as the front oozes southeast and drags the weak convection along with it. Otherwise, cloud cover and the lack of warm advection will keep temperatures seasonably cool yet again.

By all accounts, the front fails to completely pass through the forecast area. There is increasing consensus among available guidance that the baroclinic zone will hang up somewhere along the I- 70 corridor to the Missouri River in an east-west orientation tonight into Thursday morning. This front will be the focus for at least isolated to widely-scattered showers and weak thunderstorms during the day on Thursday. I cannot rule out a few stronger thunderstorms on the warm and unstable (1000-1500J/kg of weakly- capped MLCAPE) side of the boundary, mainly across the Ozarks, which would threaten wind gusts up to 50mph. Most of the activity will likely not amount to anything too impactful, and any rain that falls will prime the ground for the increased heavy rain threat later Thursday evening into Friday along this front.

MRB

LONG TERM
(Thursday Night through Tuesday)
Issued at 215 AM CDT Wed Jun 24 2026

Amidst the quasi-zonal flow that most global-scale guidance depicts overhead on Thursday, a stronger wave is consistently being modeled to track along the baroclinic zone later in the day. Exactly how fast and how potent that wave will be is still not clear, but there is increased potential that this wave will interact with precipitable water values exceeding the 90th climatological percentile (per LREF and REFS guidance) and a strengthening LLJ intersecting the front. These synoptic-scale features, favorable for heavy and efficient rain, are made more favorable by the deep warm cloud depths (10-12kft per most higher-resolution guidance) and high RH within those cloud depths. All of this is to say the environment will be primed for heavy rain and at least some degree of localized flooding where these storms track. The greatest source of uncertainty surrounds where the axis of heavy rain will exist, which is tied closely to where that baroclinic zone settles.

REFS LPMM output suggests a narrow swath of localized 3.00-4.00"+ values with a broader 1.00-2.00" values after all is said and done on Friday, which is a reasonable scenario given the favorable pattern and thermodynamic environment. While flash flooding, and perhaps additional rises on the Missouri River and its tributaries, is increasingly likely, the pretty drastic uncertainty surrounding the rainfall axis location (upwards of 75-100 miles north or south)
precluded a Flood Watch issuance with this forecast package. It is becoming increasingly likely that one will be needed soon, hopefully accompanying some increased clarity in the heavy rain location.

The wave gradually departs to our east on Friday, leaving the Mid- Mississippi Valley in a dearth of upper-level ascent and resulting in a downward trend in convective coverage and intensity. The stalled front remains in place, however, which keeps a threat for at least scattered showers and thunderstorms along with it. While timing differences exist, deterministic guidance and their ensemble counterparts agree that the front lifts north as an upper-level ridge amplifies over the central CONUS on Saturday and low-level warm advection intensifies. Rain chances shunt north as a result, but a noteworthy warmup takes hold of the region Sunday through the end of June. ECMWF EFI output doesn't suggest high temperatures will be particularly extreme (above the 90th model climatological percentile), though it does paint some higher chances of very abnormally-warm overnight lows. Regardless, with 500mb heights exceeding the 90th climatological percentile according to global- scale ensembles and 850mb temperatures even more anomalous than that, we may see our hottest conditions of the year so far. LREF and NBM temperature interquartile ranges are both fairly tight, though the distributions themselves differ a bit. This likely stems from some uncertainty around cloud cover and convective activity on the periphery of the strong upper-level ridge. Combined with dewpoints that are fairly uniformly in the low to mid-70s in most available guidance, this has the potential to result in dangerous heat as outdoor activities ramp up for Independence Day.

MRB

AVIATION
(For the 06z TAFs through 06z Wednesday Night)
Issued at 1144 PM CDT Tue Jun 23 2026

VFR conditions will prevail overnight tonight ahead of a weak cold front currently dropping south across the Upper Mississippi Valley. As it reaches the Mid-Mississippi Valley later this morning, sufficient instability and low-level moisture will likely be available to initiate scattered convection along it during the late morning and afternoon. KUIN remains largely unlikely (10-15% chance) to see thunderstorms before the front is south of the terminal, but there is an increased threat at the central Missouri and St. Louis metropolitan terminals. Given the scattered nature of the storms, PROB30s were kept at these sites and amendments will be made if a more concrete threat exists at the terminals. Following the frontal passage, VFR conditions resume through the remainder of the TAF period.

MRB

LSX WATCHES/WARNINGS/ADVISORIES
MO...None.
IL...None.