Marine Weather and Tide Forecast for Sister Bay, WI

DISCUSSION
Issued at 207 PM CDT Wed Jun 17 2026

The latest RAP analysis and satellite/radar imagery show low pressure tracking east across central Minnesota beneath a myriad of shortwave energy traversing the northern Mississippi Valley.
Ahead of the low, widespread cloud cover along with a band of light to moderate rain is spreading east across northern Wisconsin. No lightning has been detected across northeast Wisconsin so far today and mesoanalysis indicates little to no instability present across the region. As the low moves across the region, thunderstorm potential and marine hazards are the main forecast concerns.

Rain and Thunderstorm Potential: Periods of rain will continue for the rest of the afternoon and evening as low pressure moves southeast into southern Wisconsin. Rain will be most widespread where mid-level frontogenesis is the strongest, across central to east-central Wisconsin, just north of the low track. Sfc-based instability is progged to remain south of Wood and Waushara counties this afternoon, keeping the threat of strong and severe storms out of our forecast area. However, local rain amounts may reach over an inch, with the highest probabilities focused over central Wisconsin. Most of the rain will end overnight, though a few sprinkles could persist into the early morning hours along the Lake Michigan shoreline. On Thursday, partial clearing in the morning will allow sfc-based instability to build up to 500-750 J/kg beneath flat troughing and cold air aloft. With convective temperatures in the middle to upper 60s reached by early afternoon, weak shortwave impulses will provide large-scale ascent for widely scattered afternoon storms capable of producing small hail. Highs on Thursday will range from the upper 60s to lower 70s.

Long Term Outlook: Persistent upper troughing will encompass the Great Lakes to New England region over the next week. With active northwest flow aloft, this weather pattern will favor below normal temperatures and comfortable humidity levels through the extended period. The northwest flow will remain active, as several low- amplitude shortwave impulses provide periodic rain chances from this weekend into the middle of next week. Thunderstorm chances will remain low, however, as the reservoir of instability will be suppressed well south of the region. With precipitable water values averaging around 25 percent of normal, overall precipitation amounts look to be below normal despite the multiple chances for rain.

AVIATION
for 18Z TAF Issuance Issued at 1210 PM CDT Wed Jun 17 2026

Low pressure will be moving from south-central Minnesota to southern Wisconsin this afternoon to the Lower Peninsula of Michigan this evening. The surface low will bring periods of rain, isolated thunderstorms across central and east-central WI, and deteriorating ceilings and visibilities this afternoon and evening. The ceilings and visibilities should bottom out in the IFR category before improving flight conditions generally take place late tonight into Thursday morning. Generally, flight conditions should return to VFR in the 11Z-15Z time period, though uncertainty is higher across far northern WI (RHI) and near the Lake Michigan shoreline (MTW).

As the low traverses the region, winds will shift from the southeast this afternoon, to the northeast tonight, then northwest on Thursday. Gusts up to 20 kts will be possible at times.

MARINE
Issued at 207 PM CDT Wed Jun 17 2026

Southeast winds are increasing over southern and east-central Wisconsin early this afternoon. A Small Craft Advisory and Beach Hazards statement remain on track to impact areas south of Sturgeon Bay where waves of 3 to 5 feet will create dangerous swimming and boating conditions through tonight. In contrast, locations on Green Bay and north of Sturgeon Bay will see lighter southeast winds around 10 to 15 knots and waves of 2 feet or less.
Adjustments were made to cancel the beach hazards for Door County due to lower expected wave impacts and to end the marine headlines early at 09Z tonight to match the latest wind and wave forecasts as winds back to the northwest after midnight.

GRB WATCHES/WARNINGS/ADVISORIES
Beach Hazards Statement through late tonight for WIZ040-050.