textproduct: Grand Rapids

KEY MESSAGES

- Hot and Humid Through First half of the week

- Rain Chances End of the Week

DISCUSSION

Issued at 146 PM EDT Sun Jul 12 2026

- Hot and Humid Through First half of the week

As discussed previously, High pressure will track through the upper Midwest through the first half of the week. The warm air advection increases tomorrow with +22C at 850mb tomorrow afternoon/evening. That warm air advection will intensify to it's highest on Tuesday upwards of +25C. Unlike the last heat wave, there is less moisture associated with this one. However, Dewpoints by Tuesday will be in the upper 60s to low 70s. That will bring RH's to 80 to 90 Percent, especially along and south of the I 96 corridor. So while the region will be dry as far as precipitation, it will be fairly humid, especially on Tuesday. Heat Index values remain just below criteria for tomorrow, however they should build to advisory criteria Tuesday. Hight's across the region Tuesday are expected to be in the mid to upper 90s with readings of 100 likely, especially along the US 127 corridor Lansing Northward. So please take precautions this week and limit your time outdoors, make sure you remain hydrated and be mindful when walking your pets.

- Rain Chances End of the Week

The high pressure that will bring the heat through the first half of the week will be dominated by a large upper level low that will situate itself over NE Canada. There remains some questions on the timing and strength, but overall that low will drive the high pressure back into the plains and create a decent pressure gradient through the Great Lakes region. This will bring NW flow to the area. So gusty NW flow is possible Thursday into next weekend. Currently, the mid and low levels could be to dry for precip on Thursday, though afternoon convection is possible. The better chances for showers and storms is now Friday afternoon/evening. Of course depending on timing and strength of the low and the moistening of the lower levels of Southern Michigan, this timing is subject to change.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 138 AM EDT Mon Jul 13 2026

VFR conditions continue with light westerly winds expected for Monday. Overall skies will be mostly clear, but some remnant clouds from thunderstorms to the north will track through Monday morning. Maybe briefly bring ceilings around 9,000 feet, otherwise ceiling will remain above 10,000 feet.

MARINE

Issued at 150 PM EDT Sun Jul 12 2026

Overall fairly weak flow as high pressure dominates the area through the first half of the week. Waves will be less than 3 foot through most of the period. Northwest flow will intensify through the latter portion of Wednesday. That could allow waves to get to 3 to 4 feet but remain below Small Craft advisory and Beach Hazard criteria.

GRR WATCHES/WARNINGS/ADVISORIES

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