FXUS63 KGRR 250721 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 321 AM EDT Sat Oct 25 2025 .KEY MESSAGES... - Dry and Mild through at Least Monday - Increasingly Unsettled Weather for Mid-Late Week && .DISCUSSION... Issued at 321 AM EDT Sat Oct 25 2025 - Dry and Mild through at Least Monday The upper low complex that was in place over the area for most of the past week has now moved out of the area. This has allowed for broad scale ridging to build to our west, and provide increasing subsidence over the region. There is a caveat to this as a noticeable short wave is diving SE out of Canada ahead of the long wave ridge. This short wave is lacking good moisture with no moisture feed into it, and the better moisture having been swept out of the area with the departing upper low. There is some precipitation with it under the core of the wave. This is expected to remain just WSW of the area. We will see mainly mid and high clouds with this today and into tonight. Once this short wave moves away from the area by Sunday, we will see a good deal of sunny skies during the days and mostly clear nights through at least Monday night. The latest trend would be that it even lasts into Tuesday, but that is not as certain as we will talk about that in the next section. Temperatures will respond accordingly to the building ridge/heights over the area. We will see temps warm well into the 50s through Tuesday. - Increasingly Unsettled Weather for Mid-Late Week As mentioned in the previous section, there is a bit of uncertainty as to when we will see the clear skies and mild temperatures transition to more clouds and increasing rain chances for the area for the latter half of next week. The upper ridge will hold in place as we will see existing longer wave troughs/lows over the NE and SE portions of the U.S., and a long wave trough pushes over the Rockies. This western trough and supporting strong upper jet of 150+ knots will eventually make its way further east mid-week. This will eventually lead to all of the aforementioned troughs/lows to eventually consolidate for a fairly expansive upper low complex over most of the Eastern U.S.. With so many players in this scenario, and the interaction of all of them together, the details are quite uncertain at this time. It does look like the better chances of rain will stay to our south and east where there is a concentrated advection of moisture off of the Gulf and Atlantic. We will mainly see rain chances increase as a result of short wave activity around these lows, and a diurnal component with the upper cold pool becoming established under the large scale low. We may eventually see lake effect rain showers become part of the equation also with sufficient instability over the Lake and if an onshore flow is present. Right now, it looks like temperatures at the sfc and aloft will stay warm enough so that rain will be the only precipitation type. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 129 AM EDT Sat Oct 25 2025 The biggest concern with regards to aviation is the potential of impactful fog through daybreak this morning. Skies have cleared out across the area, and winds have gone light and variable, allowing for a potentially good setup. Add to this lingering moisture all day that did not mix out, and it helps the cause. The highest areas are really at all sites, with maybe a little lower chance near KGRR since they cleared out earlier. KMKG has a better chance being near the more moist air along the lakeshore. After any fog dissipates by mid morning, we will see mainly mid and high clouds the rest of the period as a weak system passes by to our SW. A few diurnal clouds around 4k ft will be possible, but VFR conditions should dominate. && .MARINE... Issued at 321 AM EDT Sat Oct 25 2025 We are looking at a break for the wind and waves for at least a couple of days after an extended period of hazardous conditions on the Lake. High pressure moving across the area and a lighter gradient will help this break. Our next SCA event looks to ramp later Monday and Monday night as the gradient tightens with a complex area of low pressure. The exact timing of this is a bit uncertain with many players and timing involved. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...NJJ AVIATION...NJJ MARINE...NJJ