265 FXUS63 KGRR 231016 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 616 AM EDT Fri Oct 23 2026 .KEY MESSAGES... - Warm End to the Week with Morning Fog - Cooler Monday-Tuesday Then Becoming Unsettled && .DISCUSSION... Issued at 326 AM EDT Fri Oct 23 2026 - Warm End to the Week with Morning Fog Tranquil and relatively warm weather persists through Sunday under a pronounced upper level ridge and large area of high pressure. Ensemble systems are practically unified with the temperature forecast through Sunday, with highs about 10 degrees above normal, in the mid 60s to around 70. True to the season, areas of morning fog has been a challenge much of this week. For this morning, patchy dense fog has developed between Whitehall and Ludington, while the air off Lake Huron invading Central Michigan has been more low stratus instead of dense fog, at least so far. Patchy fog will continue to be a possibility with radiational cooling in areas under clear skies through daybreak. There is another signal among the REFS member models for areas of fog to develop again tonight in much of central to south- central Michigan. - Cooler Monday-Tuesday Then Becoming Unsettled With a flattening of the ridge early next week, a cold front associated with a low pressure system tracking from the lee of the Canadian Rockies to Hudson Bay will likely bring cooler air into Michigan, and probably without much precip. Ensembles have more spread in temperature solutions for Monday-Tuesday, but the majority do bring cooler air with highs within the 50s to mid 60s, which is closer to normal. There is also some signal for temperatures to rebound into the 60s again midweek, ahead of a low that would track from the Pac NW through the northern Plains toward the Great Lakes. This low could bring the next best chance for about a quarter inch of rainfall around Thursday, though for now we are running with PoPs around 30 percent. Thereafter, ensembles diverge greatly regarding the positions of the large-scale northern stream trough and ridge over central North America. So this means low confidence in the forecast (for now) for the end of next week, as model solutions really contain all combinations of warm and cold, dry and wet... but not cold enough for snow yet. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 616 AM EDT Fri Oct 23 2026 IFR/LIFR mixed fog or low cloud deck has been creeping west early this morning and is encroaching on GRR, LAN, and JXN, and may reach MKG and BTL before it mixes away after 14 Z. This batch of fog and/or low cigs has been relatively easy to track on nighttime microphysics satellite images, but not easy to predict whether the vis and/or cigs at any given terminal would drop to minimums or for how long. Patchy or shallow fog may still develop by 12 Z elsewhere under the clear skies away from this main cloud deck. Once the clouds and fog evaporate, the rest of the day should feature mostly clear skies and light winds. && .MARINE... Issued at 326 AM EDT Fri Oct 23 2026 Areas of fog this morning may affect the harbors and portions of the nearshore, mainly north of Grand Haven. Today will have light winds and low waves. South winds 10-20 knots on Saturday will build waves to 2 to 4 feet north of Whitehall, persisting into Sunday morning. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Dense Fog Advisory until 10 AM EDT this morning for MIZ037>040- 043>045-050-051-057>059-066-067. MARINE...Dense Fog Advisory until 10 AM EDT this morning for LMZ848-849. && $$ DISCUSSION...CAS AVIATION...CAS MARINE...CAS

NWS GRR Office Area Forecast Discussion