Marine Weather and Tide Forecast for Monona, WI

UPDATE
Issued 945 AM CDT Sat May 17 2025

Short and long term forecasts remain on track.

Expecting the low-level clouds to linger through today, with just a few pokes of sunshine possible later. The ongoing drizzle / scattered sprinkles of rain north of I-94 are likely to continue through the rest of the morning, dissipating this afternoon.

Sheppard

SHORT TERM
Issued 328 AM CDT Sat May 17 2025

Today through Sunday Night:

Synopsis/Mesoanalysis: Upper low pressure continues to linger across the western Great Lakes this morning, leaving most of the state under mostly cloudy skies. A shortwave is pivoting around the southwest flank of the upper low, with GOES water vapor imagery placing the feature over the Black River Falls vicinity as of 3 AM.
Lift along/ahead of the shortwave has encouraged scattered sprinkle and shower development, with a scattering of stations from the Wisconsin River Valley to Stevens Point reporting light rain. The aforementioned shortwave will continue to pivot east this morning, bringing additional rain shower chances to areas primarily along and north of I-94 & US-18. Conditions will dry out this afternoon as the shortwave & its parent upper low pull east into the Saint Lawrence Valley. High pressure will build into the region tonight through Sunday, bringing partly cloudy skies and lighter surface winds.
Currently moving onshore the Oregon Pacific coast, the next disturbance will shift through the Great Basin & central Rockies today/tonight, ultimately ejecting into the Central Plains Sunday afternoon. The feature's ejection will encourage widespread shower and thunderstorm development in the Central Plains Sunday afternoon, with activity attempting to advance toward southwest Wisconsin in its decaying stages during the predawn hours Monday. Current expectations are that this precip will remain southwest of the region, though trends will continue to be monitored.

Today: Showers will linger through this morning. Best potential will focus to the north of I-94 and US-18, where proximity to the passing shortwave will be greatest. Despite greater distance from the passing shortwave, an isolated shower or sprinkle can't be entirely ruled out further south, where slight chance precip probabilities have been maintained in the overnight update. Conditions will dry out this afternoon, with continued brisk winds making it feel noticeably cooler relative to previous days.

Sunday: With high pressure moving into the western Great Lakes, more sunshine is anticipated. This should result in milder high temperatures relative to today across most of southern Wisconsin, though much weaker synoptic flow will allow the lake breeze to quickly mix inland during the afternoon hours. Thus anticipate relatively wide west-east spread in high temperatures Sunday afternoon, with readings in the 60s along/west of I-41 and 50s further east.

Sunday Night: Decaying showers/thundershowers will attempt to advance toward southwestern Wisconsin during the predawn hours, but will struggle to maintain themselves as they encounter antecedent high pressure. Have thus maintained a completely dry forecast in the overnight update, but will continue to monitor trends.

Quigley

LONG TERM
Issued 328 AM CDT Sat May 17 2025

Monday through Friday:

There is some uncertainty during this period as extended models have some timing and placement differences with the upper low and associated sfc low that will move ewd across the central USA.
Initially expect a dry enely sfc flow emanating from a large Hudson Bay high pressure area to hold back rain for Monday.

Low pressure will then track from the central Great Plains to srn IA or nrn MO by 12Z Tue as an upper wave rotates around the upper low.
The upper low will then track into IA on Tue and nrn IL Tue nt while the sfc low moves toward the Ohio River Valley. Thus lift and moisture will be sufficiently close for rain (60-80 percent) Tue- Tue nt, but lesser chances (40-50 percent) toward central WI.
As the low moves to the ern Ohio River Valley, occlusion may occur and retrograde over srn Ontario and surrounding areas. This will impact whether high pressure and pleasant wx returns for Thu-Fri or is delayed. The NBM rainfall amounts at this time range from a quarter inch over central WI to an inch near the IL border with shifts to the north or south highly probable.

Gehring

AVIATION
Issued 945 AM CDT Sat May 17 2025

MVFR cloud ceilings linger through the remainder of this morning, raising from roughly 1,500 to 3,000 ft by the early afternoon.
Some light drizzle and sprinkles of rain are evident at eastern and east-central WI terminals at the moment, expecting this activity to continue through the morning then evaporate into the afternoon. The low clouds are expected to linger through the rest of today with broken coverage in most areas, though far southern and eastern WI terminals may achieve 4,000 ft VFR ceilings later this afternoon into this evening. West to northwest wind gusts to 25 kt continue (with a few gusts to 30 kt), subsiding this evening.

About 70% confident we will see intermittent MVFR return late tonight into Sunday morning due to lingering low clouds at SCT to BKN coverage.

Sheppard

MARINE
Issued 328 AM CDT Sat May 17 2025

Breezy west-southwest winds continue across Lake Michigan this morning as 992 mb low pressure lingers near the northern open waters. Breezy conditions will continue through today as the aforementioned area of low pressure migrates toward the Ontario- Quebec border. Wind directions will turn west-northwesterly tonight as 1030 mb high pressure moves toward the Hudson Bay vicinity. The approach of this area of high pressure will allow winds to taper during the second half of the overnight hours tonight. Winds will turn due northerly during the day on Sunday as high pressure pivots into far northern Ontario.

Wind speeds will increase during the day on Monday as 1032 mb high pressure lingers over the Hudson Bay vicinity and 998 mb low pressure forms in the central Great Plains. Brisk winds will continue into the day on Tuesday, shifting east-northeasterly as the aforementioned area of low pressure moves into the Ohio River Valley during the afternoon hours. The low will move into the Appalachian Mountains on Wednesday, resulting in a northerly wind shift across Lake Michigan. Given that low pressure will be approaching and passing to the south of the open waters, winds will be gusty on both Tuesday and Wednesday. Gales are not anticipated at this time, though trends will continue to be monitored in the coming forecasts.
The approaching low will also bring chances for showers and isolated thunderstorms, with severe weather not expected. Winds will gradually taper Thursday into Friday, when 1022 mb high pressure is forecast to settle into the western Great Lakes.

Gusty winds continue in nearshore zones into the first half of this evening, when conditions will begin to taper from south to north.
Given the south-north delay, have thus elected to extend the Small Craft Advisory through 10 PM CDT from North Point to Sheboygan. The Small Craft Advisory will expire as scheduled at 7 PM CDT further south. Winds will be lighter on Sunday as high pressure builds into the Northern Plains. Both wind gusts and wave heights will increase ahead of approaching low pressure Sunday night, resulting in the return of Small Craft Advisory conditions by early Monday morning.
Anticipate that gusts and waves will remain elevated through at least mid-week, resulting in a prolonged period of hazardous conditions through Thursday morning. Will address the prolonged period of impacts with an additional Small Craft Advisory in later forecasts.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM
Small Craft Advisory
LMZ643-LMZ644 until 10 PM Saturday.

Small Craft Advisory...LMZ645-LMZ646 until 7 PM Saturday.