textproduct: Grand Rapids

KEY MESSAGES

- Warmer Temperatures with Tolerable Humidity

- Shower and Thunderstorm Chances Late Wednesday into Friday

- Warm and Mostly Dry Weekend Favored

DISCUSSION

Issued at 340 AM EDT Tue Jul 7 2026

- Warmer Temperatures with Tolerable Humidity

High temperatures today and Wednesday will be near normal to a little warmer than normal, in the mid to upper 80s away from Lake Michigan. A narrow zone of drier air will be situated under the weak ridge over Lower Michigan today, and dew points should range from the mid 50s to lower 60s, which is relatively comfortable after last week.

- Shower and Thunderstorm Chances Late Wednesday into Friday

A weak cold front will slip through Lower Michigan on Thursday, under weak upper level troughing and the right entrance region of a 250 mb jet. Increasingly moist air in the low levels and modestly steep midlevel lapse rates will contribute to about 1000 J/kg of CAPE returning. Scattered showers and thunderstorms can be anticipated.

First there is some variance in guidance whether weakening thunderstorms in Wisconsin will reach Ludington-Muskegon by sunset Wednesday. Regardless of initial time of arrival, a few thunderstorm cells do appear likely in west-central Michigan overnight, with possibly a threat of locally gusty winds.

Daytime development of thunderstorms Thursday is more favored away from Lake Michigan given the westerly surface winds expected, though additional storms from upstream could cross the lake and reach Southwest Michigan in the evening. While any storms that develop during the afternoon will occur within deep layer shear around 20-25 knots and will have a mixed lower atmosphere, it remains to be seen how moist the midlevels will be and whether DCAPE will be enough to support a marginal wind threat.

- Warm and Mostly Dry Weekend Favored

In general, high pressure is favored over the region this weekend as an upper level ridge / heat dome builds over the western- central US. Most ECE members keep us dry, but a fair number of GEFS members support a rain threat into Saturday, as they take a weak shortwave in the north-central Plains and morph it into an MCV that tracks into the southern Great Lakes. The ECE members take this shortwave and track it through the Ohio Valley. The ECE also favors Monday to be quite hot as a plume of 850 mb air greater than 20 C advects over Michigan from the west- northwest.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 100 AM EDT Tue Jul 7 2026

Not much weather concerns for aviation today. VFR expected with a few clouds 5,000 to 6,000 feet. Winds will generally be light from the north, except near Lake Michigan this afternoon where a light breeze from the west will develop.

MARINE

Issued at 340 AM EDT Tue Jul 7 2026

Low waves today with light winds mostly driven by the daytime lake breeze that will develop. Expecting south winds on Wednesday that may build 2 to 3 ft waves north of Whitehall. Weakening thunderstorms may cross Lake Michigan Wednesday evening, with a chance of affecting Ludington to Muskegon around sunset.

GRR WATCHES/WARNINGS/ADVISORIES

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