Marine Weather and Tide Forecast for Old Mill Creek, IL

UPDATE
Issued 907 AM CDT Fri May 23 2025

The forecast looks on track through the afternoon, with no significant updates anticipated.

DDV

SHORT TERM
Issued 350 AM CDT Fri May 23 2025

Today through Saturday:

High pressure will slowly move southeast toward the region during this period. General cyclonic flow at 500 mb should linger across the region as well, which will bring periodic rounds of middle level clouds through the region. In addition, diurnal stratocumulus clouds should also develop with daytime heating today and Saturday.

Some CAMs are suggesting the possibility of sprinkles or very light showers developing this afternoon and mainly Friday afternoon, and some forecast soundings are showing very weak mean layer CAPE each day. Not sure if there is enough upward vertical motion and moisture for a shower to develop today and Friday, so left forecast dry for now.

Below normal temperatures are expected during this period, with winds shifting onshore this afternoon and Saturday afternoon, keeping areas near the lake the coolest. Highs in the lower to middle 60s are expected well inland each day, with 50s closer to the lake. Lows tonight may drop into the upper 30s in parts of the inland areas, which may bring patchy frost.

Wood

LONG TERM
Issued 350 AM CDT Fri May 23 2025

Saturday night through Thursday:

We will remain in a stagnant upper level pattern through the rest of Memorial Day weekend. A middle level (500 mb) trough will extend from Maine to northern Minnesota Saturday evening, shifting through the area later Saturday night into Sunday.
Subtle ripples along this trough will cause periods of clouds and the potential for some sprinkles, but otherwise quiet weather will prevail for southern Wisconsin.

Temperatures will remain below normal with highs in the 60s.
Wind will be light and generally out of the northeast, which will keep lakeshore temps from getting out of the 50s.

The western extension of that upper trough will close off over the Dakotas Tuesday morning, when the entrance region of the upper jet shifts overhead. This will bring our next chance for rain showers into southern Wisconsin Tuesday.

That low is expected to sit over the upper Great Lakes until at least Friday. Moisture looks sparse, so our weather should probably be cooler than normal with cloudy skies with intermittent light rain showers and maybe a few rumbles of thunder. Temperatures may moderate closer to seasonal normals by the end of the week.

The ECMWF moves that closed upper low out of the region Friday night, but the GFS keeps it overhead all the way through the following weekend. Upper lows like this are not easy for models or meteorologists to predict, so keep up with the forecast.

Cronce

AVIATION
Issued 907 AM CDT Fri May 23 2025

Mostly clear skies this morning will give way to increasing clouds later morning into the afternoon as diurnal cumulus develops. The cumulus is expected to largely be in the 4-6 kft range, with coverage diminishing late afternoon into the evening as daytime heating is lost. Another round of diurnal cumulus will be possible again Saturday.

North to northwest winds generally under 10 knots are expected across southern WI today, with winds becoming northeast to east near Lake Michigan late morning into the afternoon as a lake breeze moves inland. Winds will become light and variable this evening into tonight as high pressure builds in from the north, with light northerly winds expected on Saturday. A lake breeze will move inland again later tomorrow morning into the afternoon.

DDV

MARINE
Issued 350 AM CDT Fri May 23 2025

Low pressure around 29.7 inches over Lake Ontario will move east today. Northwest winds will gradually weaken today in southern portions of the lake, and tonight to the north. High pressure around 30.3 inches will then build into the region through this weekend and into Memorial Day. Winds should generally be light from the north to northeast during this period.

Wood

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM...None.