textproduct: Grand Rapids

KEY MESSAGES

- Brief Window For Showers and Storms this Afternoon

- Dry and Cooler Wednesday into Thursday, Frost Possible

- Showers and Storms Return Friday into Saturday

DISCUSSION

Issued at 216 PM EDT Tue May 19 2026

- Brief Window For Showers and Storms this Afternoon

Thunderstorms have developed east of a Kalamazoo to Lansing line. It is in this area where surface based CAPE is highest (1500 to 2000 J/kg) with shear values around 35 knots. This is also in the area of better moisture convergence. Downdraft CAPE values are also around 1000 J/kg. With these factors strong to severe thunderstorms are possible through 5pm with damaging winds as the primary risk and small hail as the secondary. As we head into the evening our instability and shear move east with dry conditions moving in behind the cold front.

- Dry and Cooler Wednesday into Thursday, Frost Possible

High pressure builds in for Wednesday and Thursday with highs in the mid 50s to 60s. Within this cooler air mass frost is possible Wednesday night into Thursday morning mainly for inland and northern portions of the forecast area. There is a 20 percent chance that areas along and north of US-10 for temperatures at or below freezing. If winds stay in the 5 to 15 mph range overnight, frost would not be a concern.

- Showers and Storms Return Friday into Saturday

Low level moisture returns ahead of a shortwave trough expected to move through Friday afternoon into Saturday morning. This will bring another round of showers and storms to the area with drier conditions trending for the rest of the weekend into next week. There is decent agreement as seen in the cluster analysis with most members keeping the area dry with temperatures warming up again into next week.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 159 AM EDT Wed May 20 2026

A cold front has progressed through all of the TAF sites as we approach 06z with west to northwest winds now prevailing. Main post frontal concern is the extent of MVFR ceilings that may develop the remainder of the night. At this point, JXN is the only TAF site with a MVFR ceiling. We do think that there will be some expansion of the MVFR ceilings early this morning especially south and east of GRR. These lower ceilings may persist through the morning hours. This afternoon and evening VFR weather is expected. Northwest winds at 5-15 knots will veer to the north and northeast this afternoon and this evening.

MARINE

Issued at 216 PM EDT Tue May 19 2026

Winds and waves will gradually come down this evening with some isolated Small Craft Advisory gusts through the overnight. If winds trend lower the Small Craft Advisory could end earlier. A brief period of northerly Small Craft Advisory winds and 4 foot waves is possible Wednesday afternoon. Otherwise, easterly winds will keep wave heights down through the remainder of the week.

GRR WATCHES/WARNINGS/ADVISORIES

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