textproduct: Grand Rapids

KEY MESSAGES

- Areas of dense fog this morning

- Heat concerns across Southern Lower Michigan today

- Chances for severe thunderstorms this afternoon and evening

- Chances for severe thunderstorms Thursday evening/night

DISCUSSION

Issued at 413 AM EDT Wed Jun 10 2026

- Areas of dense fog this morning

We have issued a Dense Fog Advisory for this morning for northwest portions of the forecast area including Grand Haven, Muskegon, Ludington, Baldwin and Newaygo. Cooler air being pushed inland by westerly winds in the lowest 100mb is resulting in dense fog given the high dew point air in place. Other areas remain above advisory levels and we will monitor for any expansion to the Dense Fog Advisory. We feel by mid to late morning that conditions should improve to above advisory conditions.

- Heat concerns across Southern Lower Michigan today

After coordination with surrounding offices we have issued a Heat Advisory for our southern row of counties (the I-94 row). The heat is a bit borderline, but we thought it was close enough to match up with neighbors to the south and east. Jackson County probably stands the best chance at seeing triple digit max apparent temperatures. With highs around 90 to the low 90s and dew points rising into the lower 70s its going to be hot. There is a chance we may need another heat headline on Thursday especially towards Jackson once again.

- Chances for severe thunderstorms this afternoon and evening

All Southwest Lower Michigan counties are in a slight risk for severe thunderstorms today via the Storm Prediction Center. Per the latest HREF we expect storms to approach mid Lake Michigan in the 400pm hour and sweep through the forecast area between roughly 500pm and 1000pm this afternoon and evening. There are signals in the HREF that damaging winds are the primary threat with 10m AGL ensemble max gusts exceeding 60 mph, especially over the western half of the forecast area. MUCAPE values will likely exceed 3,000 j/kg today which will be coincident with a 850mb LLJ increase to 30-40 knots. DCAPE values near the convection this evening are forecast to be in excess of 1,000 j/kg which is a good indicator for damaging winds. Some lingering convection is expected into the overnight, but a downward trend in intensity is expected given the stabilizing affect of the evening rain.

- Chances for severe thunderstorms Thursday evening/night

There will likely be a lull in the activity Thursday morning and for much of the day for that matter. While today's storms will be largely thermodynamically driven, Thursday's storms will get more of a synoptic scale boost from a sharp shortwave trough sweeping in at 500mb. The low level jet Thursday evening is forecast by all of the models to at least be in the 40-50 knot range which is substantial for mid summer. Winds in the mid levels will be equally as strong with a 100 knot jet core at 500mb noted just upstream over WI/MN. Suffice it to say Thursday's convection has some dynamics associated with it. MUCAPE values will exceed 3,000 j/kg again with much stronger deep layer shear of around 40 knots. All hazards are in play on Thursday evening, but again this looks to be another damaging wind event. Max gusts in the HREF are increasing as the storms are approaching from the west at the end of the current 48hr time window of the model. SPC has us in an enhanced for Thursday which looks warranted.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 200 AM EDT Wed Jun 10 2026

Two concerns over the next 24 hours for aviation purposes are fog/low clouds this morning and chances for thunderstorms this afternoon and evening.

As for the fog and low clouds...low ceilings have spread into West Central Lower Michigan as of 06z...essentially from GRR and BIV to the north. We expect these low clouds (IFR/LIFR) to expand to the east and south encompassing almost all areas near and north of I-96 by 10z to 11z. Visibilities will be worst near Lake Michigan. The low clouds and fog should lift through the course of the morning hours. VFR weather should prevail into the afternoon.

Focus in the afternoon shifts to thunderstorm potential. While some scattered storms are possibly in the 18z to 21z time frame we expect a surge of storms to move in after 21z from the west. These storms will be capable of wind gusts to 35 knots, with isolated gusts to 50 knots.

MARINE

Issued at 413 AM EDT Wed Jun 10 2026

We have a Marine Dense Fog Advisory out this morning and that is working out well looking at shoreline webcams. We expect the fog to lift in the mid to late morning hours with mixing. Focus is on the chance of a Small Craft Advisory and Beach Hazards Statement for tonight. At this point the event looks confined to the night hours between 8pm this evening and 8am Thursday. Holding off for now and will let the day crew look at it. 3-5 footers look possible north of Holland.

Mariners will need to be prepared for high winds both this afternoon and evening and again Thursday evening associated with strong to severe thunderstorms sweeping across the lake from the west. Wind in excess of 50 knots will be possible.

HYDROLOGY

Issued at 413 AM EDT Wed Jun 10 2026

We have had some heavier rain fall across the forecast area in the past couple of days. Radar estimates from MRMS indicate that it is the northwest CWA from Muskegon and Newaygo northward through Hart and Scottville that has seen the most rainfall. 1-3 inches or rain in this area has been common with some isolated areas of 4+ which has been backed up by rainfall reports. Most of the remainder of the area has seen less than an inch.

An anomalously high moisture content is expected through the depth of the atmosphere over the course of the next 2 days with PWAT values of 1.5 to 2.0 inches today and exceeding 2.0 inches on Thursday. Sounding climatology for Detroit shows the daily max value for this evening of 1.90 inches. We will be near or above daily max values for the next 48 hours.

Forecast precipitation amounts range from 0.75 to 1.50 inches across almost the entire area via WPC. HREF 48 hour max values which normally equates well to the heaviest swaths show that 1.50 to 3.00 inches is possible. The HREF only goes through 00z Thursday evening at this point, so with additional precipitation expected with the storms Thursday evening/night it is possible we will see some amounts toward 4.00 inches in the heaviest swaths.

Good news is that area rivers are well within bank and near normal values. We should be able to absorb most of this rain without significant issues on mainstem rivers. That said, short term hydro issues are a concern. Once PWAT values approach and exceed 2.0 inches localized flooding is very possible given the strong convection we are expecting. Local short term flood advisories and warnings are possible over the next 48 hours due to urban and small streams not being able to keep up with and drain the amount of rain falling in short durations. 1-2 inch per hour rainfall rates are expected in the heaviest cells.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Dense Fog Advisory until 11 AM EDT this morning for MIZ037-038- 043-044-050-056. Heat Advisory from noon today to 8 PM EDT this evening for MIZ071>074. MARINE...Dense Fog Advisory until 11 AM EDT this morning for LMZ844>849.