Marine Weather and Tide Forecast for Old Mill Creek, IL

UPDATE
Issued 950 PM CST Sat Nov 8 2025

Mainly light snow is occurring across southern Wisconsin, with a light rain and light snow mix across areas near Lake Michigan with milder temperatures there. This activity should gradually shift southeast and out of the area overnight. Far southeast areas near the lake may see some rain/snow showers linger overnight with a lake effect band, before it shifts further east.

Wet, slushy accumulations up to an inch is possible on grassy and elevated surfaces, with mainly wet roads. Some slick spots may still occur on elevated surfaces as temperatures continue to drop overnight.

Gusty north to northwest winds will develop overnight into Sunday, with brisk and cold temperatures expected. Lows in the 20s overnight with highs only in the middle 30s are anticipated on Sunday. Wind chills will be in the teens overnight and teens to lower 20s Sunday.

Wood

SHORT TERM
Issued 306 PM CST Sat Nov 8 2025

Tonight through Sunday:

Overall, the trend continues to favor the better upper-level forcing (+100kt 250mb jet and 500mb dCVA) remaining south of the WI/IL border as the upper-level trough digs across the Midwest. This aligns well with the surface low currently tracking along the IA/MO border into central IL. Beginning to see light rain and drizzle spread across southwestern WI late this afternoon and will continue to spread eastward through the evening. Expecting as the temps drop as we head into the evening, the freezing height currently between 1.4-2kft will follow suit and lower while saturating toward the surface. In the next hour or two, will begin to see rain transition to a wintry mix of rain and snow for inland areas of southern WI.

Meanwhile areas closer to Lake Michigan may hold onto the rain a bit longer given the warmer lake temps and onshore, but eventually will see a transition to wintry mix and even snow later this evening (02z- 04z) Overall, much of the area will see the first snowflakes of the season, generally looking at fairly minor accumulations (<1").
Areas along/north of a line from WI Dells to Port Washington may see a few flakes, but not expecting much in the way of accumulations given it will have to battle more dry air and farther from the forcing. As you go south will begin to see a bit more accumulation tonight, but will have to contend with the warmer ground temps and snow rates of <0.5in/hr, thus slushy accumulations mainly expected on elevated and grassy surfaces.
Highest accumulation around half an inch approach 1 inch will be closer to the WI/IL border.

Snow chances diminish overnight into Sunday as winds turn more northerly behind the departing low pressure system. Strong push of CAA will also bring in dry, cold, brisk Canadian airmass for Sunday.
Overnight temps tonight fall into the 20s by early Sunday morning as clouds clear, but daytime temps are only looking to warm into the low to mid 30s Sunday afternoon. So we will getting a taste of winter.

Sunday afternoon through Sunday Night:

There will be another taste of winter later Sunday into early Monday morning as a deepening trough digs down across the Upper Great Lakes Region through the day into Monday. May see some scattered light snow across southern through the afternoon, but the main focus will be on the lakeshore areas. This deepening trough paired with the cold airmass and northerly winds over Lake Michigan will set up a pattern favorable for an early season mid-lake lake effect snow band.

Models have been picking up on this stronger, deepening trough since yesterday afternoon and the trend continues today. Given Lake Michigan surface temps still in the 50-55F range, delta T between SST and 850mb will range from 20-26C. Combined with fetch across the north-south extent and that trough, trends support moderate to heavy snow accumulations with wherever this band will set up. Now the big question is will this lake effect snow band waffle enough and impact southeastern WI.

The most likely scenario is winds stay north enough to keep this band offshore and impacting southern tip of Lake Michigan in northern IN, with maybe the band glancing portions of southeaster WI sticking out more into Lake Michigan (e.g far eastern sheboygan, Racine, and Kenosha). In this case could see a these far eastern areas pick up a couple of inches of snow overnight Sunday into early Monday, while areas just west toward I-41 may see just some light snow and/or even stay dry.

However, there is a suite of of models (12z ARW, 12z NSSL, 12/15z RAP, and a couple rounds of the HRRR, as well as the 12z GFS)
that do show more of a north-northeastern wind field over the Lake along with hints of a meso-low developing. IF this scenarios pans out there is a potential for a a couple hour period producing more widespread lake effect snow to spread across east central and southeastern WI with several inches of accumulating snow. While this is a more recent trend being picked up by the models, it is not out of the questions given how potent of a system this may be. If these trends continue, then can expect travel impacts overnight Sunday into Monday.
Also likely to be a wetter type snow so accompanying impacts to powerlines and trees would be possible.

Overall, the Sunday night into Monday period bears watching over the next day as a 10-20 degree shift in the winds can be the determining factor between a dry forecast and impactful accumulating snow.

Wagner

LONG TERM
Issued 306 PM CST Sat Nov 8 2025

Monday through Saturday:

The upper-level trough bringing the weekend activity begins to shift east out of the region for Monday. Southern WI will be influenced from a gradually weaken surface high as it tracks from the Northern Plains down through the lower Mississippi River Valley through Monday night. Thus looking at drier conditions and lighter winds as temps gradually warm back into the upper 30s approaching 40F for Monday.

While the influence from the high lessens into Tuesday and expecting see a warm up through the end of the week. Tuesday into Wednesday mid-range models suggest an upper-level trough to track across Upper Midwest and northern Great Lakes region. However the associated surface low is progged to remain well north of the area, resulting in southern WI firmly settled into the warm side of this system with prevailing southern winds. Will see this system drag a cold front across WI later Tuesday into midweek and will be accompanied by another round of showers along the frontal boundary, thus increased precip chances. Given the warmer trend expecting the main precip type to be rain, but if precip is delayed a bit later/overnight, could also see a wintry mix of rain/snow with this round of activity as well, but still a bit to far out to say with any certainty.

Behind this midweek cold front, not expecting a strong push of cold air, in fact model trends favor temps to quickly recover through the end of the week as upper-level ridge builds across the central CONUS. Based on the NBM as well as the ENS and GEFS ensembles, there is even an increase probability (>50%) of seeing well above normal high temps for the end of the week with mid to upper 50s and even cracking back into the 60s toward next weekend possible.

Wagner

AVIATION
Issued 950 PM CST Sat Nov 8 2025

Mainly light snow is occurring across southern Wisconsin, with a light rain and light snow mix across terminals close to Lake Michigan with milder temperatures there. This activity should gradually shift southeast and out of the area overnight.
Visibility of 1 to 4 miles and ceilings of 800 to 1800 feet AGL are expected with the light snow in southern portions of the area, including Janesville and Kenosha. Ceilings and visibility values will be higher to the north.

The Kenosha and perhaps Milwaukee terminals may see some rain/snow showers linger overnight with a lake effect band, before it shifts further east. Any wet, slushy light accumulations up to an inch would be on grassy and elevated surfaces, with the runways and roads mainly just wet.

Gusty north to northwest winds will develop overnight into Sunday, with a brisk and cold airmass expected. Ceilings should scatter our for a time Sunday morning, before becoming more broken around 5000 feet AGL Sunday afternoon. Scattered light snow showers are also possible in the afternoon.

There is potential for a lake effect snow band to move southwest and onshore across terminals close to Lake Michigan Sunday night into early Monday morning. There is still uncertainty with if and where exactly this lake effect snow band may occur, and how much snow may fall. Kenosha would have the best chances for this activity, with Milwaukee a somewhat lower chance. For now, keep up with the forecast for this period.

Wood

MARINE
Issued 950 PM CST Sat Nov 8 2025

Low pressure around 29.7 inches will move quickly from central Illinois to the Ohio River Valley overnight. North to northwest winds will increase overnight into Sunday behind the low. Gusts Sunday and Sunday night will reach gale force, and a Gale Warning is in effect for the southern half of the lake.

A Small Craft Advisory is in effect later tonight through Monday evening for gusty winds and building waves. These conditions may linger into the middle of next week.

Heavy lake effect snow is expected for Sunday night into Monday.

Winds will vary between northwest and southwest the first half of next week, while remaining gusty through this period. Winds may approach or reach gale force at times again Tuesday through Wednesday.

Patterson/Wood

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM
Gale Warning
LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777- LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...6 AM Sunday to 6 AM Monday.

Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...3 AM Sunday to 9 PM Monday.