Marine Weather and Tide Forecast for Evanston, IL

DISCUSSION
Issued at 225 PM CDT Sun Jun 15 2025

Through Monday night:

A primarily quiet short-term period still appears probable for most of the area, with a possible exception late Monday night in parts of far northern Illinois.

It's a weak MCV "fest" mainly west of the MS River this afternoon, with the nearest of these from eastern Iowa to southwest Wisconsin. Exceptionally weak flow of 5-10 kt at 500 mb and only up to 20 kt at upper jet level will result in this feature only slowly drifting east-southeast from its current position through Monday morning. Partly to mostly cloudy skies through the night due to the upstream MCVs will result in lows for most locations in the lower to mid 60s, just a bit above normal for the date.

A modest flare up in showers may occur later overnight to the northwest of the CWA from the closest MCV, and some of these may sneak into areas west of I-39 in northwest Illinois Monday morning. Not currently expecting lightning to accompany any morning showers in the far northwest CWA with little/no MUCAPE progged. Monday afternoon, another weak impulse should cross the MS River, with the initial remnant MCV over central Illinois.
Really the only modest destabilization progged for the local area Monday afternoon is west of I-39 in northwest IL and south of US Highway 24. An isolated shower or thunderstorm or two can't be ruled out in these areas.

Otherwise, expect a partly cloudy, very warm (highs in the mid- upper 80s), and moderately humid (dew points in the 60s) start to the workweek inland of Lake Michigan. Light southeasterly synoptic winds will turn onshore near the lake as a lake breeze takes shape by midday. This will keep highs near 70F along the immediate shore and in the 70s a few to several miles inland.

A MCS should develop over the upper MS River Valley Monday evening and then push southeast. Decreasing MUCAPE with southeastward extent, marginal deep layer effective shear, and poor diurnal timing point towards this possible MCS steadily weakening before it can reach portions of far northern Illinois. However, there's a small chance, if the MCS becomes forward propagating that it could push into the far northern CWA on a still weakening trend, but enough of a punch to be accompanied by some lightning, localized downpours, and gusty outflow. Introduced slight/~20% chance PoPs for areas near/north of a Harmon (southwest Lee County) to Lake Bluff IL line to account for this currently unlikely (but worth some mentioning) scenario. It will be a warm and muggy night Monday night with lows in the mid to upper 60s.

Castro

Tuesday through Sunday:

The upper-level pattern across the Central United States Tuesday through Wednesday will be characterized by broad zonal (west to east) flow with embedded shortwave-length troughs/vorticity maxima. Meanwhile, the surface pressure pattern will be dominated by a broad Bermuda high over the middle Atlantic and troughing across the southern Plains. Such a pattern will be favorable for warming temperatures and humidity levels, altogether supporting episodic thunderstorm events (including severe weather) from the Plains to Midwest.

Owing to cascading influences of successive convective events on the evolution of each subsequent shortwave and the integrity/position of the instability reservoir, forecasting when and where thunderstorms will occur as well as consequences on temperatures and cloud cover in this type of pattern can be an unforgiving endeavor more than 48 hours ahead of time. With that said, do still see a signal for a convective event locally in the Tuesday afternoon/Tuesday night timeframe, followed by another in the general region in the Wednesday afternoon timeframe. In addition, there remains a signal that convection Tuesday/Tuesday night may act to offset part of area from the peak in coverage of thunderstorms on Wednesday, though this is obviously an item of (very) low confidence. In all, the message is that the Tuesday through Wednesday timeframe will feature warming temperatures and humidity levels, as well as periods of thunderstorms in the broad Midwest region.

Toward the end of the week and into the weekend, ensemble model guidance exhibits an unusually strong signal for deep troughing to develop across the western United States and pronounced ridging to the east. As this occurs, a plume of very warm and humid air originating over the Plains will shift eastward and encompass the Lower Great Lakes. Ensemble mean high temperatures nose into the low to even mid 90s by this weekend, which with dew points climbing above 70F will result in afternoon heat indices exceeding 100 degrees. Of course, such a pattern may attracts additional clusters of showers and thunderstorms, which may delay the onset of heat. At any rate, the message for the end of the week and beyond is that the first instance of summer heat and humidity is on the horizon.

Borchardt

AVIATION /00Z TAFS THROUGH 06Z TUESDAY/
Issued at 622 PM CDT Sun Jun 15 2025

There are no aviation weather concerns for the 00Z TAF period.

NE winds near or below 10 kt early this evening will subside to near 5 kt for the night. Look for southeasterlies largely below 10 kt during the day tomorrow before veering to southerly late in the evening. Expect VFR across all sites throughout the period

Attn RFD: A few sprinkles may fall on RFD this evening with some additional showers possible during the day tomorrow.
However, no impacts would be anticipated and best guess is that the vicinity will likely remain dry through the period, so no mention of precip was included in the RFD TAF.

Doom

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