Marine Weather and Tide Forecast for Evanston, IL

DISCUSSION
Issued at 307 PM CDT Fri Apr 25 2025

Through Sunday:

Showers and isolated storms ending late this afternoon over northwest IN and east central IL as the shortwave trough and wave of low pressure move east of the area. Increasing nly winds are then expected as low pressure deepens across the lower Great Lakes while a 1030 mb high builds into ern MN and nw WI. Nly wind gusts of 30-35 mph will be possible near the lake.
Temps will fall into the 40s by Saturday morning.

High pressure will then move across nrn IL and nrn IN Saturday afternoon and night. Sly winds and warm advection will then begin on Sunday. High temps Saturday will range from near 60F toward central IL to around 50F at the lake followed by mid to upper 60s away from the lake for Sunday.

MG

Sunday Night through Friday:

High pressure will hang on for one more day as temperatures begin to moderate Sunday. This moderation will be courtesy of southerly winds and rising heights aloft as a ridge starts to build into the upper Midwest. Humidity and warmth then increase Monday as a low pressure system approaches the western end of Lake Superior. Thunderstorms are expected over the northwestern half of the CWA Monday morning as a waning LLJ leans over east into the region. MUCAPE and effective shear appears weak on the GFS, so any storms look to be sub-severe at this time. The morning storm potential will be followed by a late morning and afternoon lull with some potential scattering of the clouds. A line of storms then looks to form over Iowa and translate east with time Monday night. GFS soundings support some severe threat with 1500 to 2000 J/kg of MLCAPE, effective shear of 40 knots and modest low to mid lapse rates ranging from 6 to 7 C/km.
0-6km shear boundary parallel shear seems to suggest a linear storm threat with some QLCS potential given cyclonic hodograph curvature and 0-3km shear around 40 knots. Trends will be monitored through the weekend to pin down more accurate timing and threats for Monday. A second threat window also looks possible Tuesday pending how quickly a boundary clears us Tuesday morning and afternoon.

Beyond, high pressure moves in mid week, keeping conditions quiet, before a warm front approaches bringing rain chances toward the end of the extended period.

CM

AVIATION /06Z TAFS THROUGH 12Z SUNDAY/
Issued at 1239 AM CDT Sat Apr 26 2025

Key Aviation Messages for the current TAF period:

- MVFR cigs expected through Saturday morning

- Gusty winds to 25 knots overnight will gradually diminish into Saturday afternoon

No precipitation is expected through the current TAF period as high pressure gradually increases through the weekend. Stratus clouds have blanketed the area resulting in widespread lower MVFR cigs. there are isolated pockets of terminals observing IFR cigs, but they are mostly on the southern end of Lake Michigan and widespread IFR is not forecast. Clearer skies are gradually sinking southward out of Wisconsin and Minnesota. VFR cigs will eventually return to the terminals on Saturday. There is moderate confidence on the timing in the TAF, but it would not being surprising if around daybreak it flopped a little going VFR then back to MVFR as breaks in the clouds happen.

The last impact to terminals in the current TAF window is from the gustier wind conditions in the short term. While most of the winds are out of a "northerly" direction, it varies at specific locations (020 at KORD and points west, but 350 at GYY and areas south and east). Gusts are expected to be between 25 to 30 knots through daybreak and then gradually diminish to around 20 knots in the early afternoon. Winds should slacken by 00Z and become more widespread northeasterly.

DK

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