Marine Weather and Tide Forecast for Kane, IL

SHORT TERM
(Through Late Wednesday Night)
Issued at 304 PM CDT Tue Jun 9 2026

A remnant MCV is currently tracking along I-70 into the St. Louis metro early this afternoon, but a strong capping inversion sampled by latest KSTL ACARS soundings explain why the feature is currently precipitation free and nearby cumulus has little vertical growth. As the MCV continues eastward into IL, it should encounter an increasingly unstable airmass and gradually less of a capping inversion away from an incoming upper-level ridge, increasing its chances of developing showers and thunderstorms. CAMs are varied on how quickly this development will occur, with some solutions delaying development until the MCV exits the CWA to the east.
Overall, deep-layer wind shear is modest, but near the MCV the latest SPC Mesoanalysis has up to 30 kt of deep-layer wind shear which suggests that a transient supercell or bowing segment is not out of the question if thunderstorms can be sustained. Around 20 kt of 0-1 km wind shear and ambient vorticity near the circulation may support a brief, weak tornado in addition to isolated damaging winds. With precipitable water near 2" and slow storm motions, locally heavy rainfall is also possible. But, again, it is uncertain if development will occur in the CWA Additionally, heat index values may fall short of Heat Advisory criteria (105+ F) this afternoon/evening due to more cloud cover and airmass recovery from this morning's dissipating MCS, but some spots could still exceed values of 100 F.

Most of the showers and thunderstorms this evening into overnight are expected to shift to the northeast of the CWA as the upper-level ridge builds overhead and forcing associated with a nocturnal LLJ is focused across central IL into southern IN.

Model guidance has trend toward the upper-level ridge shifting to the east of the CWA on Wednesday, opening the Mid-Mississippi River Valley to southwesterly flow ahead of a longwave trough across the Northern Rockies and Northern Plains. In this southwesterly flow, a shortwave trough is progged to migrate northeastward from the Central Plain to Great Lakes, glancing the CWA There is variability in the timing and track of the shortwave trough but around 30 to 50 percent of HRRR membership has a capping inversion overcome with showers and thunderstorms developing across northeastern MO and west- central IL during late morning through afternoon. However, probabilities are higher in those areas during the evening with thunderstorms developing along a nearby cold front and mainly relying on an MCS with some component of eastward propagation being established. With 1500 to 3000 J/kg MLCAPE and around 20 to 30 kt of effective wind shear, a brief supercell cannot be ruled out, but mid- level dry air suggests upscale growth into clusters or an MCS could occur if a cold pool is generated. All of these factors point to a few strong to severe thunderstorms capable of damaging winds and large hail, but a lack of strong low-level wind shear lowers the tornado treat. Subtle shortwave ridging as well as decreasing instability and wind shear decreases confidence in showers and thunderstorms lingering in the CWA overnight.

The overall setup on Wednesday looks to support warmer high temperatures further into the 90s F with low-level southwesterly flow off the Ozark Plateau but also some diurnal drop in dewpoints with deeper BL mixing limiting heat index values. A further complicating factor is for potential precipitation and clouds to temper temperatures some in the northwestern half of the CWA
Therefore, the Heat Advisory was not extended beyond today, but heat index values could still flirt with 100 F during the afternoon and evening. If model guidance trends toward higher dewpoints during peak heating, then another advisory will need to be considered.

Pfahler

LONG TERM
(Thursday through Next Tuesday)
Issued at 304 PM CDT Tue Jun 9 2026

On Thursday, a more prominent upper-level trough is forecast to round the longwave trough, providing a more significant southeastward push of the cold front into the CWA and accordingly much higher confidence in the development of more widespread showers and thunderstorms. There is still variability in the timing of the front in model guidance but a general consensus that it will be moving into northeastern MO and west-central IL during the evening, closest to peak heating with MLCAPE of 2000 to 3000 J/kg indicated by most deterministic model guidance. This portion of the CWA will also favored to see the strongest deep-layer wind shear of 30 to 35 kt, favoring strong to severe thunderstorms with an initial mixed mode of supercells and line segments quickly growing upscale into a QLCS with deep-layer shear nearly paralleling the front and linear forcing. Therefore, damaging winds and a few tornadoes, as well as large hail initially, are all reasonable hazards with severe thunderstorms. Thunderstorms will generally encounter gradually lower instability and wind shear as they progress eastward Thursday night, but exactly how quickly thunderstorms weaken is uncertain.
Similar to Wednesday, it is uncertain how warm it will get ahead of the front with some possible impact from clouds, but ensemble model guidance probabilities of 100+ F are 40 to 60 percent in the St.
Louis metro, higher than Wednesday with higher dewpoints expected.

Behind the front, global model guidance is in agreement that the upper-level flow pattern across the Mid-Mississippi River Valley will be quasi-zonal, allowing subsequent wavering northward and southward of the front as a series of shortwave troughs pass.
Ensemble models have a growing consensus that the front will lift northward toward or into the CWA sometime Saturday through Sunday, providing the highest probabilities of showers and thunderstorms.
Otherwise, conditions should be mainly dry. With a cooler post-front airmass in place through the majority of the period along with clouds and precipitation over the weekend, temperatures will cooler to near and even potentially below average by early next week.

Pfahler

AVIATION
(For the 00z TAFs through 00z Wednesday Evening)
Issued at 616 PM CDT Tue Jun 9 2026

Dry and VFR flight conditions under southwesterly winds are expected through much of the forecast ahead of the next round of showers and thunderstorms. Showers and thunderstorms are most likely to occur at the end of the TAF period ahead of a front in northern Missouri/west-central Illinois. Confidence in the location of their development is low, so have opted to not include a mention of them just yet. There is a lower chance for showers and thunderstorms during Wednesday afternoon, but there is even more uncertainty in the development and persistence of this feature.

Delia

LSX WATCHES/WARNINGS/ADVISORIES
MO...Heat Advisory until 10 PM CDT this evening for Audrain MO-Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO- Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO- Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Francois MO- Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO- Shelby MO-Warren MO-Washington MO.

IL...Heat Advisory until 10 PM CDT this evening for Adams IL-Brown IL- Calhoun IL-Clinton IL-Jersey IL-Madison IL-Monroe IL-Pike IL-Randolph IL-Saint Clair IL-Washington IL.