493 FXUS63 KGRR 231717 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 117 PM EDT Tue Jun 23 2026 .KEY MESSAGES... - Showers Wednesday into Thursday - Zonal flow through rest of week - Warmer Weather Ahead && .DISCUSSION... Issued at 328 AM EDT Tue Jun 23 2026 - Showers Wednesday into Thursday Not a whole lot has changed in the forecast for the system midweek. High pressure will continue to dominate the pattern through Tuesday. A large upper level low will trek southward over the Great Lakes region. This will correspond with a short wave trough that will move across Lake Michigan with associated moisture. Along with that as written in previous discussions there will be a LLJ of 20-30kts advecting along with it. The main question remains how warm we get during the daytime. The mid level trough could allow for 6 to 7 C/km Lapse rates with MUCAPES above 1000 J/kg and DCAPES upwards of 900 to 1000 J/kg. Given the 1.1 inches of PWATs this would give this system, instability, moisture and forcing. However, if the temps are tempered, if the clouds keep the mid levels moist, then the lapse rates will remain subdued and any storm formation will be stunted. Currently, SPC is keeping the region in the general thunder with a marginal risk in Wisconsin. Given the latest RFFS this makes sense, as its CAPE is lower than other CAMS. However, as stated, there is the potential, between 22Z Wednesday until 06Z Thursday, when storms could become strong. Showers and storms will linger into early Thursday along with system passage before moving eastward Thursday. - Zonal flow through rest of week Zonal flow with fair weather will continue through the latter portion of the week and into the weekend. Temperatures will be warming up, with highs in the upper 70s by Friday and into the 80s over the weekend. - Warmer Weather Ahead The 80s over the weekend will be a taste of things to come. As the CPC has been showing in its outlooks, a warmer trend will be upon us next week. The region is expected to jump to 5 to 10 degrees above normal by next week. While there could see chances for rain, the most dominant feature next week will be the heat. High pressure over the southern United States will be juxtaposed to an upper level low over central Canada. This will leave Michigan and central Plains in the track that will bring warm air advection through the region with 850 mb temps potentially +21C mid next week. That could bring Max temps into the 90s, with dewpoints into the 70s. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 117 PM EDT Tue Jun 23 2026 Diurnal Cu are developing mainly north and east of the terminals this afternoon as high pressure tracks over the terminals. Generally FEW to SCT coverage is favored with periods of BKN possible at JXN given latest satellite trends. Cloud bases will be in the 4-5kft range. Winds around 10 knots this afternoon will become light and variable overnight. Beginning late Wednesday morning, a batch of showers will approach from the west. Conditions are forecast to remain VFR at this time with MKG seeing the best chance of showers through 18z, though there is some disagreement on timing in short range model guidance. && .MARINE... Issued at 328 AM EDT Tue Jun 23 2026 Winds and waves will continue to subside overnight through the first half of Tuesday. Gusty northwest flow could allow waves to peak at 2 to 4 feet late in the day. Not expecting headlines at this time. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...04 AVIATION...Thomas MARINE...04

NWS GRR Office Area Forecast Discussion