textproduct: Grand Rapids

KEY MESSAGES

- 20 Percent Chance for Pop-Up Thunderstorms Today

- Heat Continues with Wildfire Smoke Moving in Today into Tomorrow

- Several Chances for Showers and Thunderstorms Friday into Next Week

DISCUSSION

Issued at 240 AM EDT Wed Jul 15 2026

- 20 Percent Chance for Pop-Up Thunderstorms Today

Most if not all stay dry today, but and isolated thunderstorm is possible between 5PM to 11PM. A weak boundary moving through may be enough lift with SBCAPE values around 2000 to 2500 J/kg and precipitable water values around 1.5 inches to spark off thunderstorms in southeast and south central Michigan. If storms occur, they'll develop quickly and possibly contain gusty winds.

- Heat Continues with Wildfire Smoke Moving in Today into Tomorrow

Highs are expected to be in the 90s once more with heat index values in the upper 90s to low 100s. The smoke from wildfires in Canada will slowly move in from the north throughout the day. The RAP and HRRR bring this smoke down to the surface reducing visibilities and air quality. An Air Quality Alert is in place into Thursday. Limit time outdoors, make sure to keep windows closed, and if possible run central air conditioning with higher rated filters.

Thursday temperatures will be a little cooler with highs in the upper 80s to low 90s and heat index values right around air temperatures.

- Several Chances for Showers and Thunderstorms Friday into Next Week

Within the northwest flow we'll see heights lower slowly Thursday into Friday. Positive vorticty advection will gradually sink south with moisture increasing. Instability will also be on the rise allowing for scattered showers and thunderstorms to develop. Heading into Saturday a deeper shortwave trough is expected to swing through the region. The low level jet is trending stronger with this system along with average MUCAPE values around 2000 to 3000 J/kg. As mentioned in the prior discussion, there is a potential for strong to severe storms. With this deeper shortwave, dry air moves in for Sunday resulting in a nice summer day with highs in the 80s.

Another shortwave trough swings through Monday into Tuesday bringing additional chances for rain and thunderstorms. Temperatures on the backside will be colder with highs only forecast to be in the 70s to low 80s Tuesday and Wednesday.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 637 AM EDT Wed Jul 15 2026

No changes from the previous discussion. VFR conditions are expected initially today with westerly winds around 5 to 15 knots. Wildfire smoke will slowly move in from north to south today reaching MKG, GRR, LAN around 22Z and JXN, BTL, and AZO around 3Z. Smoke is expected to reduce visibilities into the 3 to 5 SM range, but there is a potential that visibilities could drop down to 1 to 2 SM at times. Pop-up thunderstorms are also possible today toward LAN and JXN, therefore kept the PROB 30 group from the previous forecasts. If storms develop they could produce isolated higher wind gusts.

MARINE

Issued at 240 AM EDT Wed Jul 15 2026

Winds and waves are expected to remain below Small Craft Advisory and Beach Hazard Statement levels through Friday. Northerly winds are expected around 5 to 15 knots peaking during the afternoon and early evening. Wave heights are expected to be 2 feet or less.

Thunderstorms are possible Friday but better chances exist for Saturday. Saturday winds and waves could reach Small Craft Advisory and Beach Hazard statement levels with an approaching low pressure system. Lighter winds return Sunday resulting in a nice summer day to wrap up the weekend.

CLIMATE

Issued at 240 AM EDT Wed Jul 15 2026

Here are the high temperature records for July 14 and 15.

Location July 15

Grand Rapids 95 (2013) Lansing 99 (1977) Muskegon 93 (1995) Kalamazoo 103 (1936) Battle Creek 100 (1977) Holland 98 (1932)

GRR WATCHES/WARNINGS/ADVISORIES

MI...Heat Advisory until 8 PM EDT this evening for MIZ037>040-043>046- 050>052-056>059-064>067-071>074. Air Quality Alert until midnight EDT tonight for MIZ037>040- 043>046-050>052-056>059-064>067-071>074. MARINE...None.