070 FXUS63 KGRR 271109 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 709 AM EDT Sun Sep 27 2026 .KEY MESSAGES... - Quiet weather regime continues through Tuesday - Rain chances Tuesday night through Thursday night - Fair weather again for Friday and Saturday && .DISCUSSION... Issued at 358 AM EDT Sun Sep 27 2026 - Quiet weather regime continues through Tuesday Dry weather continues through Tuesday as ridging hangs on through that time. It is not until during the day on Tuesday that the surface high finally begins to slip away to the east in response to a system moving across Canada. It is this system that will push the east coast low out to sea. High confidence in dry weather through Tuesday and maybe even Tuesday night as the new GFS and ECMWF ensembles that just came in show all 80 members dry at least through Tuesday evening. Main focus in the this period is to watch for the threat of morning fog and stratus in a moist flow off of Lake Huron. Just beginning to see some stratus now towards Saginaw Bay in the nighttime microphysics imagery. Sites along U.S. 127 are definitely showing fog and we will be monitoring visibilities. A similar setup presents itself tonight into Monday morning. - Rain chances Tuesday night through Thursday night Not a significant amount of change in the models during the mid week time frame. We are still expecting rain associated with moisture transport on Wednesday. A cold front is forecast to press in from the northwest on Thursday. The surge in moisture from the southwest with tropical origins still tries to press in, but the models look less impressive tonight. 7 day totals of rainfall may push to around an inch in our south and especially southwest, but this is not overly concerning. - Fair weather again for Friday and Saturday High pressure quickly returns for Friday and Saturday with dry weather returning after a couple days of rain. In terms of temperatures through the entire 7 day period we will be above normal much of the time, but cooling off into Friday and Saturday as northwest flow advects in colder air. Highs back into the 60s after many days in the 70s. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 708 AM EDT Sun Sep 27 2026 Main focus this morning is on the plume of low clouds and fog surging to the southwest across South Central Lower Michigan. The fog has invaded or is about to invade LAN, TEW and FPK. It is likely these low clouds advance into BTL and JXN as well. Elsewhere some radiational fog has developed in spots. Bottom line is where are looking at a period of low clouds and fog from 12Z to 15Z. By 16Z the low clouds and fog should have lifted. VFR weather is expected this afternoon and evening. Low clouds and fog look to redevelop tonight. Wind will be light out of the north and northeast for the most part at 5-10 knots this afternoon. && .MARINE... Issued at 358 AM EDT Sun Sep 27 2026 We remain in a light wind regime today through Tuesday. A bit of a north flow increase occurs today, but it should not exceed 10-15 knots. A south flow on Tuesday does the same increasing to around 10-15 knots. The result is a quiet forecast on Lake Michigan with winds largely staying below 15 knots through Tuesday which results in waves of 2 feet or less the next 3 days. Tuesday night into Thursday looks to be a more active period on the big lake with chances for rain as well as an increasing southerly flow. South winds of 10 to 20 knots with higher gusts will likely push conditions to advisory levels on Wednesday especially north of Grand Haven. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Duke AVIATION...Duke MARINE...Duke

NWS GRR Office Area Forecast Discussion