783 FXUS63 KGRR 071848 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 248 PM EDT Sat Jun 7 2025 .KEY MESSAGES... - Showers tonight South; Showers/Storms Sunday P.M. - Quiet and Mild Mid-week - Potentially unsettled weather late week && .DISCUSSION... Issued at 248 PM EDT Sat Jun 7 2025 - Showers tonight South; Showers/Storms Sunday P.M. Thankfully the area has experienced much less smoke today than the previous days. Skies have been truly Mostly sunny with just some high level cirrus spreading in from the south this afternoon. Our first focus of the forecast is on an upper short wave that is currently over IA and MO this afternoon, causing some showers and a few storms out there currently. The center of this wave is poised to move across Northern Indiana tonight and through SE Michigan early Sunday morning. We will be remaining on the cool side of this system being north of the wave. The flow from the east is very indicative of the area staying in the cooler area of this system. These should be mainly showers staying south of the I-96 corridor tonight. Instability progs show very little if any instability to be had for tonight. We will see a break in the rain chances from around daybreak Sunday through mid-afternoon. Beginning late Sunday afternoon through Sunday evening, some showers and even a rumble of thunder will become possible as a better piece of upper energy in the form of an upper low will approach the area late. Even though there are thunder chances with this front that will be moving through, the potential for strong to severe storms looks quite limited. First, even coming through during the late afternoon hours, instability stays below a few hundred J/kg. This is the result of dew points staying in the lower 50s, and some semblance of a weak cap aloft limiting updrafts. Deep layer shear looks to be sufficient for some organization with values in the 30s. However the limited instability really looks to limit the threat. Instability does look to peak over the eastern portions of the state with better low level moisture with sfc dew points in the mid to upper 50s. Once the front moves through on Sunday night, we will maintain a chance of rain showers into Monday night as the upper low rotates over the region. These will be mainly diurnal instability rain showers, scattered around. - Quiet and Mild Mid-week The upper low will move out mostly by Tuesday afternoon, except for one lingering short wave that zips in on the backside of the low on Tuesday. This short wave may be just enough coming in during peak heating to fire off a shower or storm. Once that short wave moves through Tuesday night, we will see quieter weather settle in for at least Wednesday. This is the result of anti-cyclonic flow building over the area with a Western U.S. Coast trough coming onshore. The building ridge will help warm temperatures as mid teens C at 850 mb moves in. - Potentially unsettled weather late week A weaker cold front will pass through on Wednesday. The first thing this front will try to do is to cool temperatures off some. This front will not have moisture with it, and won`t be much of a player, initially. What this front will do is become nearly stationary just south of the Southern CWA border as it lines up to the upper jet. This will set the stage for a potentially unsettled period for late in the period with possible rounds of showers and storms riding along the front. Now, the exact details of the front will be tough to point out. Then it will be tough to try to pin point times and locations of the short waves that ride along the front. The threat will be there, so smaller pops are justified for the latter half of the forecast period. What the front will do is settle in && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 143 PM EDT Sat Jun 7 2025 VFR conditions will continue for most of the TAF period. Gusty easterly winds will continue through the daytime and will subside this evening, around 00Z. A weather system moving in early tomorrow will bring a chance for light showers to the southern TAF sites. While models vary on timing and coverage, have put VCSH in AZO, BTL and JXN. No reductions in VSBYS in expected at this time. Along with that system there is a small signal for a period of MVFR cigs late tomorrow morning, between 12Z and 18Z. A better chance for showers will come Sunday evening. && .MARINE... Issued at 248 PM EDT Sat Jun 7 2025 No headlines expected at least through Sunday, with possible Small Craft Advisories Sunday night into Monday night. High pressure at the sfc this afternoon centered over Northern and Northeast Michigan will slowly move out of the area through Sunday. The gradient on the backside of the high is not quite strong enough to need and marine headlines through Sunday, and will be offshore in nature the majority of this time. Winds will increase and become onshore late Sunday out ahead of the incoming front. The winds will become from the west/northwest Sunday night and could increase enough to require a headline for that time. That will linger into Monday before diminishing. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...NJJ AVIATION...Ceru MARINE...NJJ