022 FXUS63 KGRR 191816 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 216 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 /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 138 PM EDT Tue May 19 2026 Shower and thunderstorm cells are developing in the vicinity of JXN and pose a risk of microbursts with locally gusty winds around 40 knots over the next few hours before moving east toward Ann Arbor and Detroit. Showers with a lesser chance of a thunderstorm exist around AZO, BTL, and LAN for the next couple hours. Otherwise, the weather of note for this forecast period includes gusty southwest winds becoming northwest this evening, and also areas of MVFR ceilings through Wed morning. && .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