025 FXUS63 KGRR 192347 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 747 PM EDT Tue May 19 2026 .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 /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 747 PM EDT Tue May 19 2026 Rain showers or drizzle in the vicinity of a cold front will be passing through this evening. Patches of MVFR ceilings/visibility are occurring with brief temporary IFR reported at a few locations. MVFR ceilings will likely persist in patches across the area tonight, perhaps staying prevailing into Wed morning. Clouds are favored to scatter out with bases above 3,000 feet Wed afternoon. && .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...Small Craft Advisory until 8 AM EDT Wednesday for LMZ844>849. && $$ DISCUSSION...RAH AVIATION...CAS MARINE...RAH

NWS GRR Office Area Forecast Discussion