852 FXUS63 KGRR 221034 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 634 AM EDT Tue Sep 22 2026 .KEY MESSAGES... - Slight chance of a rain shower South on Wednesday - Dry weather with slowly warming temperatures into next week && .DISCUSSION... Issued at 245 AM EDT Tue Sep 22 2026 - Slight chance of a rain shower South on Wednesday We continue to see the upper low over Eastern Iowa as of this morning, continue to weaken and lose its moisture and associated precipitation. The frontal system that was the focus of the heavy rain over the region this past weekend, has now completely separated, and the dry low level flow from the NE eat away at much of the rain. Today looks to be a dry day, while the best small chance of rain looks to be over the south on Wednesday afternoon. We look to have some diurnal cumulus development again today, but not as extensive as yesterday. This is likely due to the upper level temps moderating, and resulting instability weaker. We continue to have fairly dry conditions below 15k ft, minus the cumulus clouds. Forecast soundings show this well. There will not be much vertical development with a fairly strong inversion around 4-5k ft, especially with low boundary layer dew points. This changes a bit later tonight and Wednesday for southern areas. Most model guidance indicates that some low level moisture will rotate around the low to our south and up and over the southern portion of the forecast area. This added moisture in conjunction with weak short waves in the vicinity will be just enough for a few light showers. - Dry weather with slowly warming temperatures into next week The amplification of the upper air pattern is still expected to take shape with the low expanding over the Eastern Seaboard, and the upper ridge building to our west over the upper Plains. It might be taking a little longer for everything to fall in place than previously thought, which is fairly common with upper lows. It still looks like we will see the upper ridging build over the area, and hold in place through early next week. We will be under the confluent flow downstream of the ridge, providing plenty of subsidence for the area. Temperatures again will remain cool through Wednesday with the upper low and cold pool aloft nearby. Temperatures will moderate then as warmer air builds in and we see much more sunshine. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 634 AM EDT Tue Sep 22 2026 The terminals are free of low clouds this morning, with mainly only high clouds overhead. There are some low clouds north and south of the terminals coming in off of Lakes Huron and Erie. We expect some diurnal cumulus clouds based around 3500 ft or so, but the main deck will be up around 20k ft. Winds continue to look to become gusty by this afternoon with gusts of up to 25 knots from the east. We will see a bit more widespread cloud cover around 4k ft move in from the SE as moisture wraps in tonight. This should not be a big impact since it will be VFR. We can not rule out a sprinkle occurring at any of the I-94 terminals. && .MARINE... Issued at 245 AM EDT Tue Sep 22 2026 We continue to see the brisk offshore winds over the nearshore waters this morning, and continue through Thursday, before winds settle down a bit. The setup responsible for this continues to be the relatively strong gradient between the sfc high to our north, and the low to our south. The offshore component keeps the winds just below criteria. We will see much lighter winds by Friday, and continue through the weekend. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...NJJ AVIATION...NJJ MARINE...NJJ

NWS GRR Office Area Forecast Discussion