Marine Weather and Tide Forecast for Belgium, WI

SHORT TERM
Issued 141 PM CDT Tue Aug 18 2026

Tonight through Wednesday night:

A largely dry morning with clear skies lingering into the late morning hours has brought temperatures up a bit across southern Wisconsin. With breezy southwest winds, WAA is also well underway with dewpoints slowly rising form the west southwest to the northeast. The far western edges of the Milwaukee forecast area are getting dewpoint readings in the upper 60s.
There is a bit of uncertainty in how far east dewpoints in the upper 60s get, but the longer rain holds off the better the chances. Higher temps and dewpoints have increased instability and low level lapse rates across the region. With a cold frontal boundary expected to move through southern Wisconsin late this afternoon into this evening, the potential for rain and storms has increased. So too has the potential for strong to severe storms. SPC has put a majority of southern Wisconsin in a slight risk for severe storms (2 out of 5) which is a slight increase in coverage, duration, and strength of storms compared to earlier in the day (thanks to the lack of storms this AM).

Meso guidance still overall struggles a bit with the evolution of storms later this evening. By far every model has storms developing across central and southern Wisconsin this evening and slowly moving southeast with the frontal boundary over time.
The one thing that certain models seem to handle poorly are the storms currently moving east along the WI/IL border. This in turn just makes a difference in the strength of storms moving through far southern Wisconsin as the environment gets tapped a bit in those specific runs. If these storms stay contained to a small area, then its likely that the environment will remain primed for additional develop with the cold front. Confidence is increasing on this scenario with storms expected to percolate around 3-10 PM. Storm mode is likely to change throughout the event as effective bulk shear around 30-35 kts across western positions of the forecast area decrease to around 20-25 kts as you head east. There could be some supercellular development where dewpoints and shear is at its best. The straight hodograph from forecast soundings supports that with the potential for some larger hail. Therefore, large hail, gusty winds and lightning are the main concerns. As the storm mode becomes more linear with time the hail risk is expected to decrease.

Once the front clears this evening into tonight the rain and thunderstorm chances will fall off. High pressure will then build in behind the exiting cold front for Wednesday. Dry weather with light north to northwest winds are expected. Highs are expected to climb into the lower to upper 70s and a lake breeze could move inland Wednesday afternoon.

Patterson

LONG TERM
Issued 141 PM CDT Tue Aug 18 2026

Thursday through Tuesday:

Higher pressure is expected Thursday ahead of the next system.
High temps will be in the upper 70s/lower 80s with lows in the 60s. Winds will start out light and variable in the early morning hours, then will shift to be predominately from the west-southwest while continuing to be light.

The next cold front will move through the region on Friday with sporadic rain showers expected throughout the morning hours (20-40% chance). The main front is expected to pass over the CWA during the afternoon/evening hours with increased PoPs (40-60% chance). Showers during this time will be more widespread along the frontal boundary. There is a chance for thunderstorms with this system as SBCAPE ranges from 1200 J/kg to 3000 J/kg with the higher SBCAPE amounts near the IA/WI border which is where storms could be stronger.

After the passage of the cold front, high pressure will build into the upper Midwest from Canada. Northwesterly winds will be the predominate condition throughout the weekend which will advect cooler and drier air from Canada as well. High temps will top out in the mid to upper 70s inland and be slightly lower along the shoreline with highs in the lower 70s. RH will be around 50% each day which will be a nice relief to conditions this past week.

On Monday as the high pressure continues to push eastward, another low pressure system will begin to push into the region from Southern Canada/NE MN. Winds will shift to be from the south, advecting warmer and more moist air from the south which help set up the next chance for rain/storms. Highs expected in the uppers 70s/low 80s inland and near the mid 70s along Lake Michigan.

A cold front associated with the low pressure system will move across the CWA on Tuesday. As of right now, timing is expected to be in the late morning through early afternoon. Amount and intensity of any precipitation is uncertain at this point.

Soergel/Patterson

AVIATION
Issued 141 PM CDT Tue Aug 18 2026

Rain and thunderstorms are expected to move through southern Wisconsin this afternoon and evening. A few isolated showers and storms are moving east across the area this afternoon and should clear out over Lake Michigan in the next hours or so.
Additional storms are expected to develop along a cold front in portions of central Wisconsin late this afternoon/evening and move southeast. Storms are expected to be scattered with a few stronger/severe storms possible. Large hail, gusty winds and lightning will be the main concerns for any severe storms. Once the cold front clears this evening rain and storms chances will end. Breezy southwest winds this afternoon are expected to become light northwest winds behind the front tonight. Ceilings are expected to be around 2-4 kft within any of the rain/storms with visibilities around 2-5 SM.

For the areas that received rain there will be a potential for low stratus to develop for areas west of Madison during the early morning hours(ceilings around 500-1500 feet possible with any stratus). Low stratus should slowly rise and dissipate in the mid to late morning hours. Light north to northwest winds will persist through Wednesday evening. A lake breeze is expected to slowly moving inland which will turn winds to the east. Light and variable winds with clear skies are expected Wedensday night.

Patterson

MARINE
Issued 141 PM CDT Tue Aug 18 2026

Low pressure moving across the Hudson Bay region today will drag a cold front southward across Lake Michigan this evening.
Expect prevailing west to southwesterly winds ahead of the cold front along with a few thunderstorms through this evening. Then the cold front will push down the Lake by Wednesday bringing a north-northwesterly winds shift. Winds will weaken and become more variable as high pressure around 30.0 inches tracks through the western Great Lakes through Thursday. Southwesterly winds and thunderstorm chances return later Friday as another system is progged to bring another cold front across the Upper Great Lakes region.

Patterson

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