076 FXUS63 KGRR 161902 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 302 PM EDT Sun Aug 16 2026 .KEY MESSAGES... - Dense fog along lakeshore, frontal passage this evening - Showers and storms Tuesday into Wednesday - Showers and storms potentially next weekend. && .DISCUSSION... Issued at 253 PM EDT Sun Aug 16 2026 - Dense fog along lakeshore, frontal passage this evening Weak zonal flow along with the precipitation from earlier today has coupled with the temperature differential over the Lake and has formed dense fog along the lakeshore. A cold front is still expected to swing through the area this evening. This will bring in drier air and shift flow to the northwest. This will lift/dissipate any fog and will bring an end to the humid conditions. This cold front is drier than previously thought, however there remains chances for scattered showers as it moves through this evening. Several MCV`s moving along the MI/IN border will remain to the south, especially given the frontal movement. - Showers and storms Tuesday into Wednesday A weak positively tilted ridge will build over Great Lakes allowing for drier northwesterly flow to begin the work week. This week will be dominated by a large upper level low moving through Northern Canada. A frontal system stemming from that low will bring a good chance for showers and storms midweek. As the low drops southward over central Ontario, this barotropic low will extend a deepening mid level trough through the Great Lakes into Illinois. There is a strong upper level jet dynamics that could support storm growth and will aid in storm dynamics. Couple this with moist mid levels, thickness advection, a convergent gradient and a chance for decent CAPE and you have most, if not all, of the ingredients for decent convection. So based on the above and given model consistency, late Tuesday into Wednesday is the timeframe to watch. - Showers and storms potentially next weekend. The late week pattern is more of an enigma. As the front passes there is the potential for it to become quasi stationary as the large upper level low it emanates from moves slowly through north eastern Canada. That front currently would stretch from the NE through the Mid Atlantic and across the OH/IN valley to IL. So the question is how fast that front propagates eastward. Temps should remain near, to slightly below, normal through the week. Depending when that low ejects into the Atlantic, another frontal pattern will move in its wake and swing through late in the week, potentially next weekend bringing chances for more showers and storms. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 127 PM EDT Sun Aug 16 2026 Light rain has ended across the region and skies are beginning to clear. Still some IFR ceilings out there but gradual improvement is expected through the early overnight. As morning approaches, we`ll see some IFR fog develop, but that will burn off by mid morning as we head toward VFR conditions late in the period. && .MARINE... Issued at 253 PM EDT Sun Aug 16 2026 Trapped moisture aided by recent rainfall and humidity has cause dense fog along the lakeshore this morning. Winds remain fairly light so expecting this fog to continue through at least the first half of the afternoon until the winds shift when the cold front comes through early this evening. West winds become north tonight behind the front. A few showers and potentially a storm are possible over Lake Michigan this evening along the front. Waves will be 1 to 2 feet with a low swim risk through. The north winds should kick up 2 to 3 foot waves tonight. A low swim risk is expected Monday, then a moderate swim risk Tuesday with southwest winds with winds and waves that could be near SCA criteria Tuesday into Wednesday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Dense Fog Advisory until 6 PM EDT this evening for LMZ845>849. && $$ DISCUSSION...Ceru AVIATION...04 MARINE...Ceru

NWS GRR Office Area Forecast Discussion


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