711 FXUS63 KGRR 231837 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 237 PM EDT Fri Oct 23 2026 .KEY MESSAGES... - Dense Fog Saturday Morning; Patchy Fog on Sunday - Pattern Change ahead with chances for rain beyond midweek && .DISCUSSION... Issued at 157 PM EDT Fri Oct 23 2026 - Dense Fog Saturday Morning; Patchy Fog on Sunday High pressure will continue dominate the weather pattern with light winds and warmer air through the weekend. The light winds, high pressure, clearing skies is a great recipe for morning fog. There is some question if it forms later. However, the flow from the east should allow for moisture to converge overnight and fog to form across the region. Models remain consistent with highs 10 to 15 degrees above normal with Max temps in the upper 60s to low 70s across the lower Peninsula. The flow will shift Saturday night into Sunday and this will lessen the chance for fog development. However, given radiational cooling, clearing skies and light winds overall, patchy fog will be again possible Sunday morning, though it should be less dense than Friday and Saturday. - Pattern Change ahead with chances for rain beyond midweek The upper level pattern has the high shifting southward and flattening next week. However, sfc high pressure should remain stout enough to keep any moisture bands to only effect the northern half of the lower Peninsula Monday and Tuesday. The ensembles diverge on timing but the cold front associated with a low pressure system tracking from the Canadian Rockies to Hudson Bay will likely bring cooler air into Michigan dropping highs closer to normal, in the upper 50s to mid 60s. Warm air advection midweek will correspond with a deepening trough that will swing through the region and is the next chance showers. Pwats are potent so about a quarter inch of rainfall is possible. Models continue to diverge after in the movement, timing and postilion of the upper level pattern. So a continued low confidence in the forecast for the end of next week. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 147 PM EDT Fri Oct 23 2026 VFR conditions and light winds are expected through this evening. However, another round of LIFR dense fog is expected at many terminals overnight through tomorrow morning, particularly at LAN, JXN, GRR, and MKG. 1/4 mile (or lower) visibilities can be expected at times, and fog may be slow to diminish once again tomorrow morning, but flight categories should improve to VFR by late morning. AT AZO and BTL, fog did not materialize last night or this morning, and as such, but forecast confidence is low that these areas will remain fog-free again tonight. Some MVFR fog has been added to these terminals to represent the possibility of at least some fog filling in this gap overnight tonight. && .MARINE... Issued at 157 PM EDT Fri Oct 23 2026 Fair winds and waves will dominate the pattern today. Another round of fog will be possible Saturday and Sunday morning and may affect the harbors and portions of the nearshore, mainly north of Grand Haven. Southerly winds will increase tomorrow, upwards of 10 to 20 kots and will build waves to 2 to 4 feet north of Whitehall, persisting into Sunday morning. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...JMC AVIATION...BRC MARINE...JMC

NWS GRR Office Area Forecast Discussion