


Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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282 FXUS63 KGRR 121902 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 302 PM EDT Sun Oct 12 2025 .KEY MESSAGES... - Areas of fog forming again tonight - Warmer and drier than normal through late this week - More active weather pattern arrives for next weekend and beyond && .DISCUSSION... Issued at 300 PM EDT Sun Oct 12 2025 - Areas of fog forming again tonight Overnight radiational cooling led to extensive fog formation overnight that lingered late into the morning hours today. The same basic weather pattern of high pressure/subsidence and generally light winds remains in place for tonight. Thus, persistence alone would suggest we`ll probably see some more fog forming. One difference may be some midlevel clouds impinging on our lakeshore areas after midnight, which may lessen fog formation. More info is available in the aviation section of this discussion below. - Warmer and drier than normal through late this week Overall, yet another warmer than normal and mostly dry week is on track for West Michigan. Average highs this time of year are in the low 60s - which means our temperatures near 70 for much of the week will be about 5 to 10 degrees above average. This relatively tranquil weather is thanks to persistent high pressure that keeps regenerating to our west, putting us in the sinking air (subsidence) portion of the overall weather pattern. As this ridge of high pressure amplifies again early in the week, there is a hint in the models of a shortwave clipping us in northwest flow, which could produce some showers on Tuesday night. However, with dry air entrenched at the low levels and fairly weak forcing, this could easily end up being nothing more than some sprinkles. Regardless, ridging strengthens again with more sunshine and slightly cooler (but still above-average) temperatures for the 2nd half of the week. Overnight temperatures will probably drop down toward the freezing mark Wednesday night, so another widespread frost is very possible under clear skies. - More active weather pattern arrives for next weekend and beyond Confidence continues to grow that the general weather pattern changes starting Friday night into next weekend and beyond. This new pattern will feature a much higher zonal index of the upper level flow, allowing numerous shortwaves and lows to pass through the Great Lakes bringing periodic rain chances. We currently don`t see any specifically heavy rain events on the horizon, but definitely a more typical fall-like pattern in terms of both temperatures and rain chances as we head into the 2nd half of October. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 106 PM EDT Sun Oct 12 2025 Low ceilings have scattered out this afternoon leaving VFR conditions through the rest of the day. A lower confidence forecast exists for tonight, with fog and low clouds on the table. While the quality of low-level moisture remains persistent from what brought widespread dense fog last night, mid and upper-level clouds will be moving into the region which may hamper our ability to cool to or below our crossover temperatures. Have trended all sites except MKG to MVFR given semi-favorable radiational cooling conditions. Trended to borderline IFR at LAN/JXN where mid/high cloud cover will be lower and moist flow off of Lake Huron will be present. If cloud cover is lessened, widespread IFR and lower conditions may occur. On the other side, greater cloud cover overnight will limit fog formation. Satellite trends will need to be monitored over the next 12 hours. Any fog/low clouds that develop will burn off after sunrise. && .MARINE... Issued at 300 PM EDT Sun Oct 12 2025 Southeast winds of 10-20 knots are expected through the day, with offshore flow keeping waves below small craft levels today. Winds slowly veer to northerly by Monday Night as a system moves into the region. Increasing northerly flow to around 20 knots Tuesday into Tuesday Night may be sufficient to bring Small Craft Advisory level waves into our waters, particularly south of Holland. A second system will bring another chance for hazardous winds and waves to Lake Michigan, along with rain, Friday into the weekend. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...AMD AVIATION...Thomas MARINE...Thomas