FXUS63 KGRR 211020 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 620 AM EDT Mon Sep 21 2026 .KEY MESSAGES... - Non-zero chance of rain for southern areas into Tuesday - High confidence of dry and seasonable weather mid-week and beyond && .DISCUSSION... Issued at 229 AM EDT Mon Sep 21 2026 - Non-zero chance of rain for southern areas into Tuesday The frontal system that brought the soaking rain to much of the forecast area over this past weekend, has sank well south of the area. This has taken all of its rain with it, leaving our area dry. We are still seeing quite a bit of cloud cover over the area with the long wave upper trough/low still to our west. These clouds are mainly high clouds north of the I-94 corridor, with mid level clouds along and south of I-94. The upper low is expected to slowly rotate/dig to the SE through Tuesday. For the most part, it will keep just about all of any weather with it to the south. The exception to this is the far southern row of counties where the mid level moisture is, and a little closer to any short waves with the parent wave. The dry low level feed of air from the NE will mitigate the chances a bit. Can't rule out a little stronger shower being able to produce some light rain fall that would survive the dry air to the ground during peak heating today and Tuesday. - High confidence of dry and seasonable weather mid-week and beyond There has been good run to run consistency and agreement amongst the models and ensemble members that we will be entering quite a dry period from Wednesday through at least next weekend. The upper low is shown by most data to rotate toward the Mid- Atlantic area, while additional energy comes onshore over the Pacific NW. What this means for Michigan is that we will be under the influence of strengthening upper ridging as the upper air pattern amplifies between the two upper lows near the two U.S. coasts. This amplified pattern slows the progression of the systems, so we are looking at an extended period of the upper ridge directly controlling our weather. We will remain a tad cool on Wednesday as the cold pool aloft is slow to move out. We will then see slow and gradual moderation of the air mass due to building heights and weak warm air advection as the cold pool exits completely. Highs should gradually warm into the 70s toward the end of the week and next weekend, with cool and comfortable overnight temps in the 40s and 50s with a dry air mass in place. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 620 AM EDT Mon Sep 21 2026 Conditions have continued to improve over the last few hours. The mid clouds along the I-94 terminals earlier have moved out, leaving only the ceiling of 20k ft agl at all of the terminals. This layer will persist through the day, and some clouds around 4k will develop with daytime heating and residual moisture helping to pop the cumulus clouds. Conditions should remain VFR at all sites. Winds will also start to gust to 20-25 knots by late morning from the NE. The diurnal cumulus clouds and gusty winds will diminish toward sunset, leaving the high deck of clouds once again. && .MARINE... Issued at 229 AM EDT Mon Sep 21 2026 All headlines are down for our nearshore waters, and it is likely we will not need any for most of the upcoming week. Winds will be steady for at least a couple of days early this week. There is a decent pressure gradient between the strong high to our north, and the low to our south. The offshore component of the wind will focus the stronger winds over the open waters. We should end up just short of the wind criteria. The waves will be on the low side due to the short fetch of the offshore flow. Winds will relax a bit later this week as the stronger gradient shifts out of the area. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...NJJ AVIATION...NJJ MARINE...NJJ