569 FXUS63 KGRR 111051 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 651 AM EDT Fri Sep 11 2026 .KEY MESSAGES... - Low chance of Rain on Saturday - Showers and Thunderstorms Possible Late Monday into Tuesday && .DISCUSSION... Issued at 138 AM EDT Fri Sep 11 2026 - Low chance of Rain on Saturday Surface high pressure moves east on Saturday and return flow brings some moisture. There could be a few showers on Saturday and Saturday night. There is enough ensemble support to bump up NBM POPs from around zero to slight/low chance across the northern zones where the better moisture and lift is located. - Showers and Thunderstorms Possible Late Monday into Tuesday A shortwave trough ejects out of the northern Rockies with a surface low tracking into Canada early next week. A trailing cold front is expected to touch off showers and thunderstorms Monday night and Tuesday. Instability and deeper moisture is across northern Lower Michigan pooling ahead of the cold front, which sinks south through the forecast area on Tuesday. Precipitable water surges close 2 inches, so heavy rain potential is there as the front will be moving slowly and MBE vectors are less than 10 knots. The front stalls across the southern zones on Wednesday, with a rainy stretch of weather possible through Thursday as a surface low tracks along the front across southern Lower Michigan. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 650 AM EDT Fri Sep 11 2026 Any shallow ground fog will be dissipating early this morning then VFR conditions will prevail through tonight. && .MARINE... Issued at 138 AM EDT Fri Sep 11 2026 Winds and waves will increase Saturday ahead of a cold front and a Small Craft Advisory may be needed. Stronger winds are expected early next week and gales are possible by Monday night and Tuesday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ostuno AVIATION...Ostuno MARINE...Ostuno

NWS GRR Office Area Forecast Discussion