Marine Weather and Tide Forecast for Shorewood, WI

UPDATE
Issued 612 AM CDT Tue Aug 4 2026

The forecast is on track for later today and tonight. An approaching cold front that stretches from nw WI to nw IA will continue to decay and slow as the attendant low pressure area over Ontario moves farther away. The decaying front, and a possible outflow boundary from the storms approaching the MS River, will act as a focus for showers and storms this afternoon over srn WI. The surface convergence will remain rather weak, but PWATs are increasing to nearly 2 inches within the 850 mb thermal ridge, and MLCAPE will rise to 1000J/KG.
Expecting the initial activitiy to be scattered but then becoming more widespread through the night as broad and weak upper troughing with 500 mb height falls of 30 m moves over the region. A right entrance region of the upper jet will also aid the overall lift. Thus believe the CAMs and deterministic models for the widespread rainfall and one half to one inch amounts, greatest toward the IL border.

Gehring

SHORT TERM
Issued 115 AM CDT Tue Aug 4 2026

Today through Wednesday night:

Increasing cloud cover today ahead of a slow-moving cold front, with highs in the low to mid-80s. Instability will increase throughout the morning hours, with surface-based CAPE of 1000 to 1500 J/kg expected to build right ahead of the front during the afternoon. Very low bulk shear and minimal shear in the surface-850 mb level will prevent the majority of severe weather from developing, but an isolated microburst or hailstorm cannot be ruled out with plenty of moisture to work with (PWATs over 1.75 inch).

The front is expected to stall over southern Wisconsin overnight tonight, with additional rounds of showers and isolated storms possible throughout the overnight hours. Bulk shear increases to near 50 kt overnight, but very little forcing outside of the surface front as well as very low instability (~500 J/kg) will prevent severe activity. However, high PWATs nearing 2 inches may lead to localized flooding for regions that see multiple rounds of rainfall.

Wednesday, low pressure ejects into central Illinois, bringing additional potential for rain and storms within its northern convergent band throughout the day. Some CAMs are indicating potential for low pressure to lift into northern Illinois if overnight convection clears early enough to destabilize in southern Wisconsin. However, majority of modeling indicates a more broad region of precipitation with CAPE around 500 J/kg and PWATs remaining in the 1.75-2 inches range. Primary hazard remains locally heavy rain.

Wednesday night, precipitation tapers off from northwest to southeast as low pressure weakens and exits into Indiana. Expect lows in the upper 50s to low 60s. Rainfall totals around an inch are expected along and south of the I-94 corridor, with rainfall totals below an inch north of I-94. Close to the WI/IL border, up to 2 inches are possible (~15% chance). Locally higher totals are possible within areas that see multiple rounds of storms.

MH

LONG TERM
Issued 115 AM CDT Tue Aug 4 2026

Thursday through Tuesday:

High pressure returns on Thursday, with cloud cover slowly exiting as low pressure continues to weaken to the southeast.
Expecting highs in the upper 70s to low 80s, with light and variable winds. High pressure lingers through the overnight hours, bringing lows in the upper 50s to low 60s.

Friday, winds will shift to southerly as high pressure propagates eastward and low pressure propagates into the Hudson Bay. Expect increasing temperatures and humidity, with highs in the low 80s. Saturday, southerly winds continue, with highs in the mid-80s. Isolated pop-up storms are possible as a weak surface front moves through northern Wisconsin (~15% chances).

Saturday night into Sunday, low pressure in the northern Plains will begin to bring frontogenesis/upper level ridging to the western Great Lakes region, and a return to an active weather pattern through early next week. Expect increasing heat and humidity, with highs in the mid to upper 80s and heat index values around 90 degrees. Multiple shortwaves riding over the upper level ridging will serve as the basis for rain and storm chances Sunday through Tuesday, with exact timing and therefore intensity remaining uncertain at this time (30-50% PoPs throughout the time period will be refined as individual shortwaves become more clear later this week).

MH

AVIATION
Issued 612 AM CDT Tue Aug 4 2026

VFR conditions today into the early evening, but scattered showers and storms will begin to occur this afternoon and evening. The showers and storms will become more widespread through the night which will result in widespread MVFR and IFR Cigs developing and lasting into Wed. Areas of 1-5SM BR and light fog may occur toward sunrise Wed AM especially over south central WI.

Gehring

MARINE
Issued 115 AM CDT Tue Aug 4 2026

High pressure around 30.0 inches over the Great Lakes this morning will gradually move southeastward throughout the day as low pressure around 29.6 inches moves into the Hudson Bay, bringing southwesterly winds to the Lake today. Gusts of 25-30 kt are expected across the northern two-thirds, with conditions hazardous to small craft in portions of the nearshore regions north of Port Washington this afternoon through this evening.
Winds will diminish and become generally light and northwesterly tonight as a cold front from this low progresses southward through the lake. Thunderstorms are expected along and ahead of the front. Rain and storms remain possible through Wednesday night as this front stalls. High pressure of 30.0 inches will bring a return to light winds Thursday into Friday, with low pressure developing again in northern Canada Friday into Friday night, bringing a return to southerly winds and chances for thunderstorms into the weekend.

MH

MKX WATCHES/WARNINGS/ADVISORIES
WI
Beach Hazards Statement
WIZ052...2 PM Tuesday to 10 PM Tuesday.

LM
Small Craft Advisory
LMZ643...2 PM Tuesday to 10 PM Tuesday.