textproduct: Grand Rapids

KEY MESSAGES

- Showers and isolated storms tonight

- Showers and a few storms Thursday into Friday

- Temperatures up and down through the 7 day forecast

DISCUSSION

Issued at 257 PM EDT Tue Oct 13 2026

- Showers and isolated storms tonight

A few showers and isolated thunderstorms have developed this evening in the far southern row of Michigan counties. This activity looks to sweep east and south of the area late this afternoon. The reasoning for this is the front is surging in the same direction and winds are becoming slightly divergent off of Lake Michigan.

We expect additional precipitation to develop tonight however as the front drifts south into Northern Indiana. Mid level shortwaves working eastward through the Southern Great Lakes will interact with the nearby front and showers and a few storms will develop after sunset. The best chances for rain will come along the I-94 corridor, but we will have chance pops all the way north into the I-96 corridor. Rainfall will be on the light side on the order of a tenth of an inch or less.

- Showers and a few storms Thursday into Friday

The most impactful weather of the forecast period will come Thursday into Friday as a fall system moves through the Great Lakes. The low will be deepening as it heads east, approaching 990mb at it moves well east of the area. Winds will increase on the backside of the low on Friday with gusts over 40 mph certainly possible.

The system will be deepening as shortwaves from both the northern and southern streams phase over the Great Lakes region. The result is the low swinging through along with deep moisture and lift. Rainfall will not be overly heavy with 0.25 to 0.75 inch amounts common. Some thunder is possible given the dynamic nature of the system, especially towards I-94 given surface dew points rising back in the lower 60s for a time.

Lake effect rain showers are expected on Friday along with the driving northwest wind. Delta T's will push into the upper teens on Friday. It will be a wet day along the lakeshore for this reason.

- Temperatures up and down through the 7 day forecast

Temperatures will be on a bit of a roller coaster with 60s to around 70 for highs tomorrow. Highs will only reach the 50s on Friday and Saturday given the cold air aloft. We should push back towards 70 next Tuesday.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 128 PM EDT Tue Oct 13 2026

A weak frontal boundary just south of the state will act as a focus for potential showers late tonight. Added a prob30 for possible showers. Instability is low and so we did not include a thunder mention.

MARINE

Issued at 257 PM EDT Tue Oct 13 2026

Waves continue to subside this afternoon and the Small Craft Advisory was allowed to expire on time at 200pm. The Whitehall spotter buoy is reporting a 2.4 foot wave at the present time, with South Haven at 1.6 feet. A downward trend should continue into tonight as high pressure builds in. There will be a increase in wave heights Wednesday into Wednesday evening as north winds funnel down the lakeshore in advance of the high. We feel these waves will likely stay below advisory criteria in the 2-4 foot range.

The next time frame we are monitoring is Thursday night into Friday behind the passage of a fall low pressure system. Northwest wind crank up rapidly. We are likely looking at gale force winds with this system as cold air advection will be effective at building waves.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...None.