Marine Weather and Tide Forecast for Port Washington, WI

UPDATE
Issued 1055 AM CDT Fri Aug 14 2026

Have pulled back on precip probabilities through this afternoon given ongoing and anticipated trends.

Current water vapor imagery shows an MCV over the Missouri Valley, with a compensating area of shortwave ridging in place immediately downstream/over southern Wisconsin. Surface observations reveal a bifurcated frontal pattern regionally, with a warm front draped over central Iowa, and an effective/convectively-modified boundary extending from the Missouri-Iowa border southeast to the Ohio River. Placement of boundaries is leading to a "zoned" warm sector, with modest instability values in place along/south of the warm front & more extreme values restricted to the south of the southern boundary. Driven in large part by 850-700 mb warm advection north of the warm front, a prior band of showers is decaying over northeast Iowa & northern Illinois as it encounters the shortwave ridging/subsidence in place over southern Wisconsin.

With the initial/leading band of showers falling apart, and the MCV-related forcing & warm sector not pulling into the area until this evening, have thus reduced precip probabilities through 7 PM, with a now entirely dry forecast prevailing through the afternoon across the majority of southern Wisconsin.
Have maintained some ~15-30% values near the WI-IL border, where a light shower can't be entirely ruled out as better forcing begins to approach. Expect better rain chances post-sunset. Will be discussing this potential in greater detail in the early afternoon update.

Quigley

SHORT TERM
Issued 1250 AM CDT Fri Aug 14 2026

Today through Saturday:

The existing line of thunderstorms spanning from east IA to central IL should slowly sag southward through the predawn hours this morning, leaving us with dry weather. A decaying complex of storms originating from IA may clip far southwestern WI post-dawn this morning based on 00z CAM guidance (20-50% chance, mainly for Lafayette and Green county only), though instability would be extremely limited if it even makes it here (likely not enough for thunder, but included slight chances to play it safe). Additional shower and storm activity near and south / southwest of the state border will continue through the daytime hours today, with slight chances for a stray cell to drift and decay into our region.

Higher and more widespread chances for showers and thunderstorms arrive tonight into Saturday morning as weak low pressure lifts northeast from KS, but there is plenty of uncertainty on how this will play out. I really mean it when I say "uncertainty" this time... check out the 14.00z HRRR: two nocturnal convective complexes initiate, one crashes through northern IL, the other through far northwest WI, and southern WI gets dry weather. Then for another scenario, check out the 13.21z RAP, 14.00z NAM and NAM NEST, the southern convective complex crashes into southern WI and delivers widespread rainfall lasting through early Saturday afternoon. In either scenario, instability is very limited (HRRR mean MUCAPE below 500 joules). Not expecting any strong to severe storms, just efficient rainfall if applicable.

Sheppard

LONG TERM
Issued 1250 AM CDT Fri Aug 14 2026

Saturday night through Thursday:

Weak low pressure continues east from the Great Lakes region on Sunday, likely deepening slightly and dragging a cold front across WI. The exact arrival time for the front is not yet certain, but the initial NW wind shift is currently favored for the early morning (predawn) hours, followed by the arrival of lower dewpoints (low 60s or potentially even 50s) on these same winds and / or a secondary backdoor cold front (with NE winds) Sunday afternoon.
In the 500mb pattern, we do have a 500mb shortwave trough that could phase well with the warm sector over IN / IL Sunday afternoon, but that doesn't leave us much to work with in southern WI. A round of showers or weak thunderstorms along the initial frontal passage Saturday night into Sunday morning would also (potentially) leave some cloud cover to interfere with peak heating, limiting the instability when the afternoon secondary baroclinic zone / backdoor cold front arrives. All this to say Sunday's storm setup leaves a lot in question, but the odds of any strong to severe storms are relatively low for now. Overall rain chances 50-65%, peaking early Sunday morning and tapering into the afternoon.

Predominantly dry weather expected Sunday night into Tuesday morning as high pressure passes overhead, with temperatures near seasonal norms. Shower and thunderstorm chances return late Tuesday through midweek as a surface trough of low pressure sweeps east across the midwest.

Sheppard

AVIATION
Issued 655 AM CDT Fri Aug 14 2026

Fog and lower ceilings this morning may linger for another hour or so, but will lift as temps warm and easterly winds increase through the morning. While cannot rule out a stray shower in southwestern or south-central WI today, expecting mostly dry conditions and breezy easterly through the afternoon. Then this evening looking at shower chances increase from southwest to northeast later this evening into Saturday morning with moderate to heavy rainfall and better thunderstorm potential along with lower flight conditions for areas closer to the WI/IL border.

Wagner

MARINE
Issued 1250 AM CDT Fri Aug 14 2026

Synopsis: Multiple rounds of storms are expected to cross the southern portion of Lake Michigan into this weekend due to a front that remains in place south of the lake. Low pressure of 29.7 inches over Kansas will track to the northeast and east toward southern Lake Michigan into tonight and Saturday. This low should help to bump up winds and waves across the southern two thirds of Lake Michigan into Saturday. Beyond this system, a broad ridge of high pressure of 30.1 inches will push into the Great Lakes early next week before another potential front moves through the region midweek.

Nearshore Zones: Breezy southeast winds and building waves are expected late tonight into Saturday, with Small Craft Advisory conditions possible.

Sheppard

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