textproduct: Grand Rapids

KEY MESSAGES

- Showers and storms possible this afternoon into Saturday

- Showers and storms possible late Sunday into Monday

- Strong to Severe storms possible late Monday

DISCUSSION

Issued at 148 PM EDT Fri Aug 7 2026

- Showers and storms possible this afternoon into Saturday

The southerly flow will continue through the day with a westward shift of the winds as the day continues. There remains small chances for showers and thunderstorms this afternoon and early evening southeast of Grand Rapids. While there remains the potential, the late of instability should stifle convection.

The best area for storms remains east of Kalamazoo. Latest CAMS continue to show the dwindling potential for convection. Any rainfall should aid the potential for shallow ground fog to reform Saturday morning.

- Showers and storms possible late Sunday into Monday

The next chance for convection will be Sunday into Monday. A large upper level low situated over Hudson bay will dominate the pattern through the first half of next week. This low will drag a mid level and surface boundary through the region early next week. This will coincide with good PWAT anomalies the are present through the atmosphere. With mean PATS of 1.5 to 2 inches, along with a slow moving surface boundary over the area Sunday through Monday, there will be the potential for heavy rain. As such WPC has Michigan in a marginal risk of excessive rain fall Sunday into Monday, and slight risk Monday into Tuesday. So will have to keep an eye on how the boundaries set up and move, and or don't move. The biggest area of concern for now is south of the I 96 corridor, especially along and south of the I 94 corridor.

- Strong to Severe storms possible late Monday

As the above mentioned boundary moves southward, it should interact with some warm and moist air as it advects along the frontal. Given the potential for moderate deep layer shear along this boundary, daytime highs in the 80s and dewpoints in the 70s SPC already has southern Lower Michigan outlooked for the potential for severe storms Monday afternoon and evening. There remains a fair amount of questions and interactions to take place though it is something that we will continue to watch.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 127 PM EDT Fri Aug 7 2026

Visible satellite loop shows abundant diurnal cu across the region. Much of that will dissipate toward sunset. High pressure overhead means light winds tonight, which will help in some fog formation toward morning. The fog and lower ceilings won't last more than a few hours, however, as the high will drift east and southwest to west winds will increase to 10 to 20 knots.

It's still possible we could see an isolated shower or storm develop late this afternoon closer to the eastern terminals, but that's far less than certain and was not included in the TAFs.

MARINE

Issued at 158 PM EDT Fri Aug 7 2026

The biggest concern for marine today is the dense fog along the lakeshore. The cooler water temperatures along with the weak flow has allowed for dense fog along the lakeshore today. This fog should linger into the afternoon. As the winds shift to the southwest and increase it should allow for any fog to lift and dissipate as the afternoon continues. Latest webcams show it beginning to clear at Grand Haven. So expect it to slowly clear from south to north through the afternoon.

The strong flow should remain below advisory criteria with one notable exception. Winds and waves north of Pentwater should reach SCY criteria late this afternoon and continue through the first half of the overnight period.

The next time frame of concern is Sunday when an increase in southwesterly winds may push conditions to advisory levels. latest models continue to show the potential for southwest winds of 15-25 knots which could allow waves to grow towards 4 feet.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Dense Fog Advisory until 6 PM EDT this evening for LMZ847>849. Small Craft Advisory until 11 PM EDT this evening for LMZ849.