textproduct: Grand Rapids

KEY MESSAGES

- Fog Likely Tonight, Locally Dense Fog Possible

- Warmup into Wednesday With Low Rain Chances Mid-week

- Dry and Cool Late Week

UPDATE

Issued at 1035 PM EDT Sun May 24 2026

The entire cwa has been included in the dense fog advisory, which is in effect until 11 am Monday. Visibilities continue to fall to a quarter mile or less and given the generally clear skies and little to no wind and recent rain, improvement isn't expected through the overnight hours.

DISCUSSION

Issued at 152 PM EDT Sun May 24 2026

- Fog Likely Tonight, Locally Dense Fog Possible

Rain showers and isolated thunderstorms associated with an occluded front crossing the area should exit by early evening. Concern then develops for fog overnight given low-level moisture from today's rain. Winds subside and skies begin to clear as high pressure moves in tonight, with a favorable environment for fog development resulting. Signals are present in guidance that pockets of locally dense fog could develop depending on the extent of clearing overnight and to what extent any sunshine today can mix. Climatology suggests that given a strong sun angle in late May, widespread dense fog is unlikely, matching the picture guidance shows. We will continue to monitor trends going into tonight.

- Warmup into Wednesday With Low Rain Chances Mid-week

West Michigan sets up on the periphery of a large scale ridge starting later Monday into Tuesday with the development of an omega blocking pattern over the central CONUS. 850 mb temps warm into the mid teens Celsius resulting in highs in the 80s. There are two low chances of rain for the first half of the week. First is Monday where convergence off Huron may pop an isolated shower across our northeast CWA. Confidence is low, with PoPs 10% or less. Second is Wednesday with the arrival of a backdoor cold front. Moisture quality is marginal so only light precipitation is expected. Medium range model guidance suggests enough MUCAPE will be present thunder to be in play.

- Dry and Cool Late Week

The post backdoor cold frontal environment will be slightly cooler than the first half of the week, with highs in the upper 70s likely. Compared to yesterday, guidance has trended towards the warmer solution with 850mb temps in the low teens. The omega blocking persists with a surface ridge in place across the region. This keeps the forecast dry for the later portions of the week.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 730 PM EDT Sun May 24 2026

Mixture of flight categories currently as clouds after the rain have varied between IFR or MVFR ceilings, to scattered or few. After a wet day, the scattering of clouds this evening going into a calm night is a recipe for fog. Dense fog has been present over portions of the Lake Michigan shoreline, and is expected to spread over MKG later this evening. IFR to LIFR visibility, ceilings or vertical visibility is favored to develop over much of the area between 03 and 06 Z. Visibility may be near minimums late tonight. Fog will mix out with drier air above between 12 and 14 Z, then the rest of Memorial Day is likely to be VFR.

MARINE

Issued at 238 PM EDT Sun May 24 2026

Webcams show that fog has already developed across the nearshore waters as of 230 pm Sunday afternoon and is already dense. Have moved up the Dense Fog Advisory to start immediately.

--- Original Discussion ---

Primary concern for marine interests is the potential development of fog across the waters tonight. Ample low-level moisture paired with a approaching high pressure system looks to calm winds enough for fog development overnight. Climatologically, the cooler waters favor fog development, which is also supported by model guidance. As a result, will be issuing a Marine Dense Fog Advisory from late this evening through mid Monday morning.

As for winds and waves, Time/Height wind overviews suggest largely that light winds and sub-advisory waves are expected over the next several days. Winds in the 1-3kft range look to approach 30-35 kts later Monday into Tuesday, however the strong warm air advection in place suggests these winds won't mix down. Other than the aforementioned Marine Dense Fog Advisory, headlines are not anticipated over the next week.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Dense Fog Advisory until 11 AM EDT Monday for MIZ037-043-050-056- 064-071. Dense Fog Advisory until 11 AM EDT Monday for MIZ038>040-044>046- 051-052-057>059-065>067-072>074. MARINE...Dense Fog Advisory until 10 AM EDT Monday for LMZ844>849.