394 FXUS63 KGRR 191818 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 218 PM EDT Fri Jun 19 2026 .KEY MESSAGES... - Light Rain Saturday morning; Cooler temps continue - Heavy rain Possible Late Sunday into Monday && .DISCUSSION... Issued at 215 PM EDT Fri Jun 19 2026 - Light Rain Saturday morning; Cooler temps continue Downsloping, northwesterly flow continues to dominate the pattern today with fair weather CU across lower Michigan. Breezy northwesterly winds will filter through the weak ridge that is over the region. That ridge will be short lived as a shallow short wave propagates through the Great Lakes tonight through tomorrow morning. Enough mid level moisture is present to create some scattered showers tonight into early tomorrow morning. Best QPF will be north of I 96, mainly along the lakeshore from Muskegon northward. Latest model have around an inch of PWAT. The 75th percentile of the ensembles is showing around a quarter inch of precipitation possible by 12Z Saturday. 90th percentile is slightly more. There is also a chance the best moisture remains north and we only get light amounts. Given that variability, while a brief downpour will be possible tonight into early tomorrow morning, a tenth of an inc h of QPF overall is more than likely. Any rainshowers will move quickly eastward tomorrow morning. The persistent northwesterly flow will keep temperatures 5 to 10 degrees below normal for the foreseeable future. So Max temps through next week are expect to remain in the 70s. - Heavy rain Possible Late Sunday into Monday The next chance for rainfall will be Sunday night into Monday. Models remain consistent that a low pressure system, supported by an upper level short wave, will track across the Midwest. Latest ensembles and the EC move the lows track slightly northward. That would increase QPF throughout the region, with the I 96 corridor receiving 0.75 to an inch of QPF and the the I 94 corridor receiving an inch to an inch and a half. Latest NBM is trending this way given the position of the low and the fact that the NAEFS and EC ensembles shows Anomalous moisture through this timeframe. Soundings through this timeframe are stable with a lack of shear. So while a rumble of thunder is possible, it`s not expected. WPC does have the area along and south of I 94 in a slight risk for excessive rainfall due to heavy rainfall potential. The low will move eastward Monday. After a few days of clearing skies, The large upper level low that has been driving the pattern should drop southward mid to late week. Timing varies but precipitation will be possible late Wednesday through Thursday. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 114 PM EDT Fri Jun 19 2026 SCT to BKN diurnal Cu are expected to continue through this evening around 5kft inland of the lake shadow (meaning cloud cover will be little at MKG through the afternoon). Tonight, widespread clouds move in ahead of a cold front along with scattered showers that have a low chance of affecting the terminals, with a PROB30 at GRR/MKG where the chance is best. MVFR cigs have a moderate (50-60%) chance of development based on RRFS/other model soundings, highest at GRR. Any low ceilings should dissipate by mid morning given strong June sunshine. Gusts to around 20 knots expected through the afternoon before diminishing this evening. && .MARINE... Issued at 213 PM EDT Fri Jun 19 2026 While there is gusty northwesterly flow, it`s light enough for only 1 to 3 foot waves today and tomorrow. Not expecting any headlines through Sunday. Next chance could be Monday in the wake of the exiting system. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ceru AVIATION...Thomas MARINE...Ceru

NWS GRR Office Area Forecast Discussion