textproduct: Grand Rapids

KEY MESSAGES

- Poor Air Quality and Reduced Visibilities From Smoke Thursday

- Several Chances of Showers and Storms Through Early Next Week

- Temperatures Cooling Through Early Next Week

DISCUSSION

Issued at 230 AM EDT Thu Jul 16 2026

- Poor Air Quality and Reduced Visibilities From Smoke Thursday

Primary forecast concern over the next day is impacts from near- surface and aloft wildfire smoke across the area. ASOS observations show widespread visibilities in the 1-3SM range as a result of smoke. Some areas across Lower Michigan have fallen as low as 1/2SM at times in the last 24 hours, and cannot rule out similar conditons here as another pocket of near-surface smoke arrives near daybreak. HRRR/Canadian smoke guidance shows near- surface smoke persisting through the day today. Air quality observations show unhealthy to locally hazardous conditions, and an Air Quality Alert remains in effect areawide from Michigan's Department of Environment, Great Lakes, and Energy.

- Several Chances of Showers and Storms Through Early Next Week

A series of fronts and shortwaves drive several shower and thunderstorm chances through early next week. First is Friday with a warm front crossing the area. However, low-level moisture quality is poor limiting precipitation potential. A cold front Saturday brings greater potential for showers and storms, along with ample CAPE and decent kinematics. However, ample MLCIN will help put a check on storm development, with the best chance east of US-127 into southeast Michigan. Given the ample CAPE/Shear, any storms that develop could be strong to severe, so forecast trends will need to be monitored. Another cold front Monday Night into Tuesday brings a third round of shower/storm chances to the area.

- Temperatures Cooling Through Early Next Week

850mb temps will fall from near 20C over the next day or two to the low to mid teens by mid next week. This will cause highs to fall from the low 90s Thursday/Friday to the low 80s by early next week. With lower post-frontal dewpoints expected after the front bringing smoke to the area tonight, heat indices will be limited to the 90s, cooler than previous days.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 628 AM EDT Thu Jul 16 2026

According to ASOS observations, widespread IFR conditions continue across the terminals this morning due to near-surface smoke with periods of LIFR at some terminals. This is likely to continue through late morning until daytime mixing allows for improvement to MVFR with intermittent IFR possible through much of the rest of the TAF period. Smoke has also led to the development of an effectively MVFR ceiling, dipping below 2kft at times. Overall, wildfire smoke will lead to significant impacts to aviation over the next 24 hours.

MARINE

Issued at 645 AM EDT Thu Jul 16 2026

Webcams show widespread dense smoke north of Holland with smoke starting to become dense south of Holland. In collaboration with other Lake Michigan offices, have issued a Dense Smoke Advisory through early afternoon. Will let day shift reassess to see if an extension is needed as daytime mixing develops.

--- Previous Discussion Issued 230 AM EDT Thu Jul 16 2026---

Widespread smoke is expected across the waters with visibilities below one mile possible at times. If confidence increases in lower visibilities a Marine Dense Smoke advisory may be needed. Between Friday morning and Saturday, a series of fronts bring the potential for isolated thunderstorms over the waters. In addition, strengthening northwest flow is expected to develop Saturday, causing waves to build to at least 3-5 ft. This makes it likely conditions will be hazardous to small craft and boaters.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Air Quality Alert until midnight EDT tonight for MIZ037>040- 043>046-050>052-056>059-064>067-071>074. MARINE...Dense Smoke Advisory until 2 PM EDT this afternoon for LMZ844>849.