Marine Weather and Tide Forecast for Kenilworth, IL

DISCUSSION
Issued at 119 PM CDT Sat Apr 18 2026

A very cold upper trough (with 500 mb temperatures at an impressive - 38C) will continue its trek across the Great Lakes region tonight into Sunday. After the diurnal increase in cloud cover, expect rapid clearing this evening. As mentioned for the past few discussions, the northern periphery of a modest mid 1020s mb high will be centered southeast of the region across the ArkLaTex, thus outside of a few outlying locations, we'll hold onto at least some surface flow through the night.
Additionally, there will be an increase in higher cloud cover late tonight in the northwest the coldest temperatures are forecast, but this would probably come in a little late to prevent the temperature fall. While there are some factors that would tend to limit the expansiveness of the frost threat, areas of frost certainly may occur in more sheltered locations to warrant a Frost Advisory tonight away from the urban core.

We will maintain the chances for showers on Sunday. A shortwave on the back side of the upper trough will eventually get absorbed into the bottom of the trough axis with time, however there will be a period of moderately strong lower level forcing. Moisture is not overlying plentiful, but cold temperatures aloft will support a significant steepening of the low level lapse rates and lead to scattered showers. The top of the cloud layer, while relatively shallow, may get just close enough to the charge separation layer to ring out a lightning strike or two, but the bulk of calibrated thunder guidance from both the HRRR/REFS suggest this would be isolated. With the steep lapse rates, breezy conditions may be augmented by any showers with a few gusts to 35 mph certainly plausible.

There is much higher confidence in frost/freeze conditions on Sunday night with a surface high to be in place overhead. There is the potential with onshore flow that there could be some lower cloud cover near the lake to keep things in check in both the IL/IN near lakeshore areas. A Freeze Watch will get hoisted to cover this.

There is also a strong ensemble signal for a bounce back to early summer-like temperatures Tuesday through Thursday. The only fly in the ointment for an overall nice mid week period will be on Tuesday.
Some guidance (mainly the GFS) squeezes out some showers--likely under an incoming EML plume--ahead of a cold front Tuesday afternoon and evening. Forecast soundings at this time look too capped for thunderstorm development, although very steep lapse rates aloft suggest we'll need to keep an eye on this. CMC/EC ensemble suites are not biting yet on this solution quite yet and few any members wring out any precipitation.

Thereafter, a closed large upper low off the Pacific coast will sweep through the Upper Midwest towards the end of the week. While there are some uncertainties as to how this system will evolve, it will send several synoptic shortwaves in our direction late week through the weekend. The first will arrive in the Friday timeframe with a robust cold front. This will bring the next thunderstorm chances to the area late frame. 1" + PWAT values will accompany each of these waves, and with potent forcing we may see some re- aggravation of hydrologic issues during this time. Confidence is also quite high that temperatures will drop back below normal.

KMD

AVIATION /18Z TAFS THROUGH 00Z MONDAY/
Issued at 1213 PM CDT Sat Apr 18 2026

18Z Forecast Highlights:

- VFR cumulus cloud streets this afternoon through 00z.

- Breezy, 25-30 kt, westerly winds prevail through the afternoon then diminish this evening to less than 10kts overnight.

- Westerly winds increase Sunday morning, with a chance of sporadic showers throughout the region during the afternoon.

Post frontal overcast clouds continue to shift eastward across northern Indiana, with development of diurnal cu cloud streets across northern Illinois lasting through 00z. Breezy conditions this afternoon, with westerly gusts in excess of 25-30kts will continue to hold VFR ceilings in place. After 00z, winds diminish below 10kts heading into the overnight, with skies clearing throughout the forecast area.

Another disturbance will dive into the Midwest on Sunday, leading to another increase in west-northwest winds and bringing the potential for sporadic showers across northern Illinois into northern Indiana.

Baker/KMD

LOT WATCHES/WARNINGS/ADVISORIES
IL...Frost Advisory from midnight tonight to 9 AM CDT Sunday for ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012- ILZ013-ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039- ILZ106-ILZ107-ILZ108.

Freeze Watch from late Sunday night through Monday morning for ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012- ILZ013-ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039- ILZ103-ILZ105-ILZ106-ILZ107-ILZ108.

IN...Frost Advisory from midnight CDT /1 AM EDT/ tonight to 9 AM CDT /10 AM EDT/ Sunday for INZ001-INZ002-INZ010-INZ011- INZ019.

Freeze Watch from late Sunday night through Monday morning for INZ001-INZ002-INZ010-INZ011-INZ019.

LM...Small Craft Advisory until 10 PM CDT this evening for the IL and IN nearshore waters.