012 FXUS63 KGRR 161136 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 736 AM EDT Sun Oct 16 2022 LATEST UPDATE... Aviation .DISCUSSION...(Today through next Saturday) Issued at 334 AM EDT Sun Oct 16 2022 A dynamic weather pattern is unfolding for the Great Lakes over the next couple of days. On the surface, a cold front will move across the cwa this morning. IR loop shows a deck of mid clouds is moving out of the cwa and we may see some sun this morning before clouds move back in again. A strong short wave over Manitoba will move south today and bring a stronger shot of cold air with it. The end result will be cold advection throughout today. However, by tonight, as h8 temps fall below 0c, we'll see lake effect showers develop thanks to deep moisture and lake delta t/s in the lower 20s. The northern cwa will likely see some snow mix in with the rain showers tonight. The warmer water over the lake will create MUCAPE in the 100-300 j/kg range and so thunder is a possibility over the lake and the lake shore counties. Highs Monday-Wednesday will only be around 40 degrees...well below normal. Given the cold air, a couple inches of snow are possible over the far northern cwa on non road surfaces during short bursts of heavier snow showers. For the most part, sfc dewpoints remain above freezing through Wednesday, so sfc temperatures aren't going to go below freezing. Given soil temperatures in the 40s, quite a bit of melting will be going on, so we are not going to get carried away with accums. The upper low begins to lift out Wednesday night and temperatures will warm to the mid to upper 50s by the end of the week under generally dry conditions. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 728 AM EDT Sun Oct 16 2022 As colder air flows in from the west today...clouds and eventually showers will be on the increase. A period of MVFR clouds looks possible late this morning or this afternoon. The pattern for impacts increases later tonight as widespread MVFR and pockets of IFR develop as a result of increasing lake effect showers. The atmosphere will become increasingly unstable beyond 12z Mon so we may see a few thunderstorms then. A risk for west to northwest wind gusts over 25 knots will develop late tonight and more so Monday...especially for KMKG as the pressure gradient tightens up and the mixing heights increase. && .MARINE... Issued at 334 AM EDT Sun Oct 16 2022 A cold front is moving across the lake early this morning. Wind will eventually become northwesterly today. The colder air will increase wave heights and a Small Craft Advisory remains in effect through tonight. Low pressure will drop south across the state and we'll see winds increase significantly Monday into Tuesday. A Gale Warning is now in effect from early Monday through Tuesday. Gales to 40 knots are expected. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Small Craft Advisory until 5 AM EDT Monday for LMZ844>849. Gale Warning from 5 AM Monday to 8 PM EDT Tuesday for LMZ844>849. && $$ DISCUSSION...04 AVIATION...MJS MARINE...04