Marine Weather and Tide Forecast for Oostburg, WI

SHORT TERM
Issued 440 AM CDT Tue May 20 2025

Today through Wednesday:

Synopsis/Mesoanalysis: An upper trough is moving into the western Great Lakes this morning, with increasing lift and moisture transport encouraging rain shower development to the southwest of Madison. Lift will continue to increase across the entirety of southern Wisconsin this morning, allowing widespread and steady rainfall to overspread the area from the south by early afternoon.
Rain will become more scattered in nature this evening, with scattered shower chances continuing through Wednesday afternoon as the aforementioned upper trough lingers in the vicinity. Currently centered along the Iowa-Missouri border, low pressure will move across north-central Illinois today, resulting in gusty east- northeast winds through this afternoon. Gusts will gradually taper this evening through Wednesday as the low shifts into the Ohio River Valley, though generally breezy conditions will continue through Wednesday afternoon. The combination of breezy/gusty conditions, overcast skies, and abundant rainfall will support continued well below-normal temperatures through the duration of the short term period.

Rest Of Overnight Through Today: Currently evident in regional radar mosaics, widespread & steady rainfall will continue to overspread the region from the south. Rain will be occurring in an unseasonably moist environment, as confirmed by upstream 00Z soundings from Davenport and Lincoln, IL, which sampled precipitable water values in the 1.1-1.25"+ range. Given the aforementioned environment, will thus be monitoring for localized pockets of moderate to briefly heavy hourly rainfall rates through this afternoon, though potential should be curbed by an overall lack of MUCAPE across southern Wisconsin. Forecast soundings do nevertheless show weak (~100 J/kg) MUCAPE to the southwest of Madison & near the state line, so brief embedded convection/enhanced hourly rates can't be ruled out in these locations. The widespread & steady nature to today's rains will result in the bulk of anticipated rainfall accumulations through tomorrow. Areas along & south of the I-90 and I-94 Corridors are favored for 1"+ of accumulation, with lighter totals moving northeast into east- central Wisconsin. Totals reaching/exceeding 2" can't be ruled out, particularly in southwest Wisconsin where chances for embedded thunderstorms are greatest. Don't anticipate widespread flooding impacts given the long duration of rainfall, though ponding of water on roadways & minor river rises are possible.
Winds will be gusty through this afternoon as low pressure moves to our south. Widespread gusts between 30-40 MPH are anticipated, with isolated gusts to 45 MPH possible during the late morning and early afternoon hours. Held off on Wind Advisories given the expected isolated coverage & brief nature of 45+ MPH gusts, but will continue to monitor trends through this morning.

Tonight Through Wednesday: Rain will become more scattered in nature as the best moisture transport shifts east. A brief lull in rain could even occur through early evening as dry air attempts to work in near the 700 mb level. With the upper trough lingering in our vicinity through Wednesday afternoon, scattered rain shower chances will nevertheless continue.

Quigley

LONG TERM
Issued 440 AM CDT Tue May 20 2025

Wednesday night through Monday:

Chances for showers (20 to 30 percent) should linger at times Wednesday night into Thursday and perhaps Thursday night, as enough low to mid-level moisture lingers with passing differential CVA in the mid-levels. The moisture starts to thin out Thursday night, despite more passing vorticity maxima associated with a passing 500 mb low to the northeast.

Temperatures should remain below seasonal normals during this period, as modest cold air advection on north winds pushes into the area. If high pressure can get close enough to the area Thursday night and weaken winds/clear skies, some frost may occur as lows could fall into the middle to upper 30s away from the lake.

Ensembles are generally showing that high pressure system remaining to the north of the region this weekend into Monday, which may allow for the area to perhaps dry out at times and slowly moderate temperatures. There is uncertainty this far out in the forecast, as several ensemble members still want to keep precipitation at times, as northwest flow at 500 mb keeps vorticity maxima rotating through the area. Moisture will be key to any showers occurring.

Temperatures look to shift back more toward seasonal normals inland from Lake Michigan during this time per ensemble members. Onshore winds near the lake should keep these areas cooler.

Wood

AVIATION
Issued 440 AM CDT Tue May 20 2025

Rain will continue to gradually overspread the region through this morning. Brief Heavy rainfall and a few storms are possible at times mainly southwest of Madison through this afternoon, where the best moisture and upward motion will linger the longest.

CIGs will drop to below 1000 feet AGL by this afternoon and linger tonight into Wednesday. Visibility of 1 to 4 miles should occur with the more steady rain today, lingering into Tuesday night. Gusty east winds are expected through this afternoon. Rain may become more scattered Tuesday afternoon and Tuesday night, lingering into Wednesday.

Quigley/Wood

MARINE
Issued 440 AM CDT Tue May 20 2025

Low pressure around 29.5 inches will approach southern Lake Michigan today. The low track will result in easterly winds across Lake Michigan. Winds will become gusty, especially across the southern half of Lake Michigan. Confidence in periods of gale force gusts has increased across southern Lake Michigan in the overnight forecast, particularly from this morning through the first half of the afternoon hours. A Gale Warning has thus been issued between 4 AM and 4 PM CDT across the southern third of the open waters.

The low will shift into the Ohio River Valley tonight into Wednesday, allowing winds to shift to the north Wednesday afternoon.
Periods of showers and isolated thunderstorms will accompany the approaching and passing area of low pressure today through Wednesday. Severe weather is not expected.

High pressure around 30.1 inches will move into the Western Great Lakes Region Thursday through Friday, allowing winds to gradually taper across the open waters.

Small Craft Advisory conditions continue early this morning across all nearshore zones. Wind gusts will increase further this morning and afternoon as low pressure approaches southern Lake Michigan.
Confidence in gale-force wind gusts has increased in the overnight forecast, with peak potential being this morning through the first half of this afternoon from Port Washington south. The Small Craft Advisory has thus been upgraded to a Gale Warning from 4 AM CDT to 4 PM CDT from Port Washington to Winthrop Harbor. Winds will shift northeast tonight into Wednesday, then north Wednesday night into Thursday. Waves of 5 to 9 feet are expected into Wednesday morning, then become 3 to 5 feet Wednesday afternoon into Thursday. Showers and isolated thunderstorms are forecast today through Wednesday, with severe weather not expected.

Quigley/Wood

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM
Gale Warning
LMZ080-LMZ644-LMZ645-LMZ646-LMZ671-LMZ673- LMZ675-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-LMZ878 until 4 PM Tuesday.

Small Craft Advisory...LMZ644-LMZ645-LMZ646...4 PM Tuesday to 4 PM Thursday.

Small Craft Advisory...LMZ643 until 4 PM Thursday.