Marine Weather and Tide Forecast for Wilmette, IL

DISCUSSION
Issued at 231 AM CDT Sat May 17 2025

Through Sunday:

Only forecast concern are the winds through early this evening.
Westerly winds will gust into the 35-40 mph range today and will steadily diminish with sunset this evening. Light northwest winds tonight will shift northeast Sunday with a lake breeze/ cold front.

Much of today will be mostly cloudy with perhaps some breaks and partial clearing this afternoon, especially across northwest IL.
There may be a few sprinkles or an isolated shower near the IL/WI state line, but no mention with this forecast.

High temps today will only reach into the 60s with lows tonight in the mid/upper 40s for most locations. Highs on Sunday are expected to reach the low/mid 70s well inland. Only medium confidence for high temps closer to Lake Michigan with the above mentioned cold front moving through and eventual northeast winds where high temps may only reach the lower/mid 60s. cms

Sunday Night through Friday:

A returning warm will become quasistationary across southern Iowa and central/southern Illinois on Sunday night. While warm advection will increase steadily atop/north of this boundary into Monday morning, forecast soundings from most global guidance really don't look supportive of much precipitation production locally, with a generally fairly dry column in place. Even through the day on Monday, the main shower and thunderstorm chances look to remain mostly south of our forecast area.

The aforementioned stalled front looks like it will attempt to push slowly northward late Monday afternoon and evening although this boundary will remain solidly south of the forecast area.
Large scale forcing for ascent is expected to increase through Monday night as a surface low (progged near or just under 1000 mb) develops across northern Missouri along the cyclonic shear side of a northward-advancing jet streak. A notable increase in upper jet divergence, in concert with mid-level height falls and nocturnally intensifying isentropic ascent should lead to the expansion of showers and thunderstorms from Iowa across central and northern Illinois. With near moist adiabatic lapse rates in place, instability on forecast soundings appears pretty limited, generally under a few hundred J/kg. At the same time, deeper tropospheric moisture will start to push northward out of central Illinois, with PWATs forecast to increase towards 1.5" into early Tuesday morning. This combination may set the stage rain with embedded thunderstorms with a locally heavy rainfall threat into Tuesday morning. The likely to categorical PoPs from the NBM seemed reasonable during this time period.

Tuesday may end up being a pretty raw day, with fairly widespread showers persisting through most of the afternoon.
Widespread cloud cover and strengthening winds off the lake suggest that the NBM-delivered temperatures in the lower 60s may be a bit too generous, and some cuts may be needed in that department going forward. At this point, it looks like the quasistationary boundary will remain far enough to our south to curtail a severe risk through this time frame as well.

Precip activity will become a bit lighter through Tuesday night into Wednesday as we start to lose deeper moisture. Broad upper troughing is forecast to remain in place into Thursday, but the arrival of a drier airmass should tend to shut precipitation chances off through Wednesday night with seasonably cool conditions to close out the week.

Carlaw

AVIATION /12Z TAFS THROUGH 18Z SUNDAY/
Issued at 605 AM CDT Sat May 17 2025

The key aviation messages are:

- MVFR cigs this morning lifting to VFR midday into the afternoon

- Westerly winds gusting around 30 knots at times this morning, easing this evening

- Lake breeze will turn winds northeasterly midday/early afternoon on Sunday at the Chicago-area sites

Overall, there are no major weather concerns. Westerly winds will gust around 25-30 knots this morning and afternoon before easing and becoming northwesterly this evening. MVFR cigs with bases near 020-030 will gradually lift to VFR by this afternoon.

Carlaw

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM...Small Craft Advisory until 7 PM CDT this evening for the IL nearshore waters.

Small Craft Advisory until 4 PM CDT this afternoon for the IN nearshore waters.