282 FXUS63 KGRR 210629 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 229 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 /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 139 AM EDT Mon Sep 21 2026 A much less impactful forecast for aviation interests as compared to the last couple of days. VFR is expected to dominate, except for some isolated MVFR ceilings early this morning. The lower clouds have just about all pushed south of our terminals as of early this morning. KGRR had some isolated 2500 ft ceilings, but that has since cleared out. The I-94 terminals still have a 6-9k ft agl ceiling, which will likely remain through most of today. Areas north will likely just have the high 20k ft deck, with maybe some isolated cumulus developing mid-late morning. Winds will become a bit gusty with diurnal heating today from the NE. Gusts up to 25 knots will once again be possible, especially at the northern sites where the heating will be a little better with less layers of clouds. The diurnal cloud cover and gusty winds will diminish toward sunset tonight. && .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

NWS GRR Office Area Forecast Discussion


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