Marine Weather and Tide Forecast for Port Washington, WI

UPDATE
Issued 600 PM CDT Wed Mar 18 2026

Monitoring water vapor imagery early this evening, which shows a compact disturbance from northwest Wisconsin toward the Minnesota Boundary Waters vicinity. Said disturbance will continue to progress southeast through late evening, passing over northeast and east-central Wisconsin during the ~10 PM - 7 AM time frame. Increasing mid-upper level lift ahead of the disturbance, broad warm advection in the 1000-925 mb layer, and a narrow zone of frontogenesis rooted near the 925 mb level will support the potential for rain or freezing rain in the vicinity of the system's track late this evening through the overnight hours. Tend to agree with depictions of simulated precip in recent mesoscale guidance, which are suggesting that rain/freezing rain will be confined to a narrower band, with the band ultimately materializing where 925 mb frontogenesis is maximized. Outside of the frontogenesis zone (in particular, with south and west extent in the MKX forecast area), much weaker lift will struggle to overcome dry conditions in the lower portions of the column. Will thus be planning to tighten mentionable precip probabilities to locations along & north of I-94 in the evening update, with a narrow area of ~10-15% probabilities & drizzle/freezing drizzle mentions surrounding the higher probs.

Whether rain/drizzle or freezing rain/freezing drizzle occurs will depend on surface temperatures at the onset of precipitation. Will thus be closely monitoring temperatures through the overnight period. While pavement temperatures are mostly above freezing in the anticipated area of precip, will need to watch trends through tonight. Even if pavement temps remain above freezing through tonight, will need to be monitoring for a glaze of ice on elevated & untreated surfaces through early tomorrow morning. Will have additional details in the evening forecast update.

Quigley

SHORT TERM
Issued 157 PM CDT Wed Mar 18 2026

Tonight and Thursday:

Warm advection aloft will persist through the remainder of today and into tonight. Clouds associated with the departing system continue to gradually decrease from the southwest, with a period of mostly clear skies possible later this afternoon into the evening. Best chance for clearing is across the southwest half of the forecast area. Despite the warm air advection aloft, the clearing skies and light winds along with the widespread snow pack may lead to temps falling a good amount through the evening hours (especially southwest areas), before clouds associated with approaching shortwave put a damper on any radiational cooling. Could also see some fog develop tonight, mainly across the southwest half of the forecast area where there is a better chance for prolonged mostly clear conditions.

The big concern tonight is whether there will be enough moisture in the low and mid levels for period of measurable precip as the shortwave moves through. The 12Z GEFS mean probability for at least 0.01" liquid is less than 10% for most of the forecast area tonight, with 10-30% in the far northeast. The NAM is similarly dry, though a couple of the 12Z CAMs are relatively bullish with a band of precip dropping southward through the area the second half of the night into early Thursday morning.
If precip does indeed develop, there is a concern for a round of freezing rain given the potential for colder surface temps in place at the onset of the precip. Limited the higher precip chances (40-60%) and totals towards the northeast based on the bulk of 12Z guidance, with lower chances (20-30%) in the southwest.

There is also some question about temps tonight across the northeast half of the forecast area, as any lingering clouds might result in temps right near or slightly above freezing.
Could see a mix of rain and freezing rain in these areas if precip does develop. Given the overall uncertainty with this system, will be holding off on an Winter Weather Advisory for freezing rain for now. Cloud trends into this evening as well as the development of precip upstream over the next few hours should better clarify the potential for local impacts overnight.

Clouds may linger much of the day tomorrow, with light easterly winds expected. Even though temps aloft will be fairly mild, these conditions along with the lingering snow pack will likely keep surface temps from warming that much. Kept highs towards the lower end of guidance and could still be a degree or two too mild.

DDV

LONG TERM
Issued 157 PM CDT Wed Mar 18 2026

Thursday night through Wednesday:

Low pressure is expected to pass by to the north Thursday night, dragging a cold front through southern Wisconsin by early to mid morning Friday. This system generally looks dry for the forecast area. Confidence is not great in high temps for tomorrow given the tight temperatures gradient across the region in addition to the front dropping through. Could end up seeing highs several degrees cooler than currently forecast given a faster cold front (as models seem to be trending towards).

The frontal boundary is expected to lift back through the region as a warm front on Saturday ahead of an approaching low. There is a question as to how far north the front will make it, with the 12Z NAM and Canadian solutions suggesting the front will struggle to make it far into the forecast area (if at all). The 12Z GFS and ECMWF solutions continue to suggest the front will make it all the way through southern Wisconsin, resulting in a mild day under south to southwest winds. The chilly waters of Lake Michigan often beat back a warm front this time of the year though, so wouldn't be surprised to see the front struggle per the prior mentioned models. The latest forecast does keep somewhat cooler temps in the northeast, with the best chance for above normal temps from Madison southwestward.

The frontal boundary will likely have shifted back south of the WI/IL border by daybreak Sunday, with cooler conditions likely across southern Wisconsin. Even cooler temps are expected Monday as high pressure slides into the area from the northwest. Temps are expected to moderate back towards or even a bit above normal by mid-week.

DDV

AVIATION
Issued 600 PM CDT Wed Mar 18 2026

Clouds have temporarily cleared in the far west late this afternoon. While said clearing hasn't reached the vicinity of MSN and JVL, will be evaluating the need for near-term amendments to sky conditions in the coming 00Z update. If clearing is realized at JVL and MSN, mid-upper clouds will build back in by mid-late evening ahead of an upper disturbance approaching from northern Minnesota.

Continue to expect that the aforementioned disturbance will bring some rain and freezing rain chances to the area tonight into early Thursday morning. There remains a lot of uncertainty as to whether the precip will impact southern Wisconsin, as models have been generally trending drier and farther north with the precip through this afternoon. Will be evaluating the need for PROB30 and/or prevailing precip groups in the upcoming 00Z update.

There is the potential for some fog tonight, particularly within areas of clearing given light winds expected. Low clouds are likely to return as well as the shortwave moves through, with lingering clouds possible across at least the northern half of the forecast area on Thursday.

DDV/Quigley

MARINE
Issued 157 PM CDT Wed Mar 18 2026

Breezy south to southwest winds will continue through late afternoon as low pressure of 29.8 inches pass by north of Lake Michigan. The current 5 pm CDT expiration time of the Small Craft Advisory still looks good based on latest expected winds and waves. High pressure of 30.2 inches will then move overhead tonight and Thursday, bringing lighter winds to the lake. Light to moderate south to southwest winds are then expected Thursday night into early Friday ahead of a cold front, with winds becoming northerly through the day Friday as the front drops through the area. Breezy southerly winds are expected Saturday ahead of an approaching low, with gusty northerly winds likely Sunday behind the low and associated cold front.

DDV

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