Marine Weather and Tide Forecast for Lake Forest, IL

DISCUSSION
Issued at 142 PM CST Tue Mar 3 2026

Through Thursday Night...

It's a gray early March day out there today with low-hanging overcast residing atop the area. The cloud cover has kept conditions cooler out there than yesterday with temperatures early this afternoon sitting in the upper 30s and lower 40s.
Meanwhile, a sharp baroclinic zone is draped across south- central IL with an impressive density gradient on either side; a stretch of only about 50 miles presently separates mid 40s temps from mid 60s. A series of subtle impulses transversing the baroclinic zone is driving waves of showers across central IL.
Most coverage since early this morning has stayed south of the CWA, but a few lighter showers have found their way across our south.

The remainder of today will be pretty steady state with the occasional light shower possible south of US Rt. 24 into this evening. There's a signal from a handful of camps for rain coverage to expand across central IL as another vort lobe scoots across and possibly targets our southern tier of counties for steadier rainfall late this evening through much of the night.
The rest of the area will be staying dry tonight and we'll probably even see some clearing across maybe the northern half of the CWA Areas that do see clearing, particularly those west of the Fox Valley, may see some fog develop overnight into Wednesday. With stronger flow residing just off the surface and mixed signals from model guidance, opted to leave any explicit fog mention out of the forecast for tonight.

Shower coverage is expected to continue prioritizing areas south of the CWA into Wednesday. It wouldn't be surprising to see the whole area rain-free throughout the morning and maybe much of the afternoon as well. Early in the day, a surface low will begin to lift northeast into the region across MO and eventually into central and northern IL by Wednesday night. That baroclinic zone, acting as the cyclone's warm front, will propagate northward during the day and rain coverage will follow suit. Scattered showers may move over our southern and southwestern CWA as early as the afternoon, but some of the latest high-res guidance suggest we may not see much precip expand into the area until the evening. Densely scattered to widespread showers are then expected around most of the area through the night and into Thursday.

With guidance coming into better agreement on the surface reflection passing directly overhead, there is a growing signal for western and northwestern portions of our CWA to see generally lesser rain coverage on the northwest side of the low track during this period than areas farther south and east. As many as several hundred Joules of elevated CAPE will lift into northern IL Wednesday night into Thursday. Ambient forcing should be sufficient with steep lapse rates atop the stable layer to provide a decent shot at some elevated convection. The event should wrap it up in the form of scattered lighter showers late Thursday morning into afternoon as the low pulls away to the east. Thursday night will be quiet before our next opportunity for rain arrives early Friday.

The low tracking overhead will also provide us with a good setup for widespread fog tomorrow night. Visibilities are expected to drop from south to north as the warm front approaches during the evening. There is a signal that dense fog could be possible in our south early enough to impact portions of the evening commute. Chances will only build and expand northward moving into the late evening and overnight. The fog may also attempt to linger well into the morning which could potentially mean hazardous travel around the Chicago metro for the Thursday morning commute. With strong support from guidance, decided to add fog area-wide to the forecast for Wednesday evening into Thursday morning.

Doom

Friday through Tuesday...

On Friday, mid-level southwesterly flow will strengthen as a mid- level jet ejects northeast across the Plains into the Upper Midwest. This will send a low amplitude mid-level shortwave racing northeastward into the Upper Midwest sometime late Friday morning into early Friday afternoon, though there is variance in the guidance regarding the track and strength of this feature.
Scattered showers and thunderstorms accompanying this feature may impact parts of the region for a period into Friday afternoon.
However, it still appears there will be a good amount of dry time during the day (more than implied by the currently high gridded PoPs).

Temperatures on Friday are expected to soar well into the 60s into the low 70s (near record territory for ORD and RFD which is 70 at both sites on Friday) for most through the afternoon as a surface warm front surges northward across Illinois and Indiana.
However, as is typical this time of year, onshore flow ahead of this front across far northeastern IL (including parts of Chicago)
may keep conditions much cooler through much of the day until the warm front clears this area. The combination of these very warm temperatures and unseasonably high dew points, into the upper 50s to near 60, will support an unstable and strongly sheared warm sector supportive of a conditional threat of severe thunderstorms Friday afternoon. The main question at this point is if any of these early afternoon storms will be able to become surface based near the quickly approaching warm front before the main focus for them shifts to our northeast later in the day. If they do become surface based, then severe storms would be more of threat for a period Friday afternoon, particularly near the surface boundary.
However, at this time confidence on severe threat with these storms is low at this time. Ultimately, it is going to come down to the timing of the northward frontal surge into northern IL Friday afternoon.

A period of storm free weather could set up for a period late Friday afternoon and evening following this initial impulse, though south-southwesterly winds do look to become gusty (35+ mph) for a period. Expect shower and thunderstorm chances and coverage to ramp-up again late Friday night into early Saturday morning in association with a cold front sweeping eastward across the area. The currently unfavorable diurnal timing of the cold front passage does raise questions as to the threat for organized severe weather with this activity locally. However, the combined presence of near record warm temperatures and dew points Friday night with a strongly sheared kinematic environment certainly will support at least a conditional risk for some stronger storms capable of damaging winds late Friday night.

Rain chances will come to an end following the cold frontal passage on Saturday, at least for a few days. Temperatures will cool down a bit immediately behind the front Saturday PM, but generally remain well above average through early next workweek.
For areas that don't receive much rain in the upcoming stretch, we'll need to monitor for elevated fire danger on Sunday due to mild temps paired with fairly low dew points and gusty southwest winds. Current medium to long-range ensembles point towards a stronger cold front passage in the wake of a possible formidable mid-latitude cyclone with potentially widespread precipitation mid next week, bringing a return to colder conditions by later in the week/mid-March.

KJB/Castro

AVIATION /18Z TAFS THROUGH 00Z THURSDAY/
Issued at 1135 AM CST Tue Mar 3 2026

Key messages:

- Low MVFR CIGS persist through early this evening before improving.

- Some VSBY restrictions in light fog and haze this afternoon, with some patchy fog possible tonight.

- MVFR CIGs expected to return sometime late morning to early afternoon on Wednesday, with conditions likely deteriorating to IFR/LIFR Wednesday evening and night.

A deck of Low MVFR to IFR stratus will persist across the area terminals this afternoon, along with some haze and light fog.
We then look to see a gradual north-to-south improvement in CIGs this evening as the lower level flow turns northeasterly and pushes the area of stratus south of the main terminals.
However, as this occurs, light winds and ample low-level moisture could foster some patchy fog tonight, particularly outside the main Chicago terminals.

Low MVFR CIGs are expected to shift back northward on Wednesday as the low level flow off the surface shifts southerly again.
While the exact timing of their return to each terminal remains somewhat unclear, the general late morning into early Wednesday afternoon appears to be the most favorable time. CIGs and VSBYs will deteriorate more into Wednesday evening and night (likely IFR to LIFR) as the next weather system approaches the area.
However, this will primarily occur beyond the current 30 hour TAF period for ORD and MDW.

KJB

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM...None.