


Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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886 FXUS63 KGRR 060832 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 432 AM EDT Sun Jul 6 2025 .KEY MESSAGES... - Showers and Thunderstorms Likely Today - Chances (20 to 40 percent) for Showers and Storms Mid-Late Week && .DISCUSSION... Issued at 405 AM EDT Sun Jul 6 2025 - Showers and Thunderstorms Likely Today Localized 40-60 mph wind gusts and several narrow swaths of 1 to 3 inch rain totals are possible today as scattered thunderstorms develop in a moist atmosphere with PW around 2 inches. Rain showers and perhaps some thunderstorms are favored to develop this morning in the vicinity and northwest of a line Holland to Grand Rapids to Mount Pleasant as a wave along the front passes through with CAPE less than 1000 J/kg. Instability increases during the afternoon with surface heating and arrival of a 500 mb trough, reaching about 1500 J/kg to the east of the Holland-GR-Mt Pleasant line. Broad surface troughing and general low-level convergence ahead of the cold front will help scattered thunderstorms develop throughout the afternoon. The storms will produce very efficient downpours given the high-PW atmosphere today. Effective deep-layer shear is marginal but could reach 20-30 knots, so some limited organization could occur with a few better hail cores. The fallout of any hail cores that pulse up and the relatively colder downdrafts that result raises the possibility of wet microbursts and locally gusty winds. - Chances (20 to 40 percent) for Showers and Storms Mid-Late Week Overall ensemble guidance shows several weak shortwave troughs that move through at times next week. There is variability overall in both the timing and depth of these shortwave troughs. Either way with the moisture in place any disturbance could spark off showers and thunderstorms. Given the ensembles and the overall timing, feel the the NBM PoPs (20 to 40 percent) are reasonable mainly during the Tuesday night into Wednesday, Thursday, and Friday timeframes. Diurnal heating could help bump chances slightly during the afternoon and early evening hours. With this set up though, no one day looks like a washout. Additionally, temperatures will be more seasonable with highs in the 80s and lows in the upper 50s to mid 60s. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 240 AM EDT Sun Jul 6 2025 MVFR to IFR ceilings from the north will spread into MKG this morning. MVFR ceilings will gradually spread southeastward, reaching GRR later in the morning (approximately 15Z) and JXN by no later than this evening (approximately 02Z), per a consensus of short-term models. But flight category is liable to drop to temporary IFR sooner than ceilings would suggest due to moderate- heavy rain showers and scattered thunderstorms. These should affect MKG and GRR vicinity this morning then GRR vicinity and many areas south and east of GRR this afternoon. && .MARINE... Issued at 432 AM EDT Sun Jul 6 2025 Southwest winds over Lake Michigan veer northwest then north as the day goes on. The veering winds will occur earlier in the day the farther north you are. Generally, waves will be 2 to 4 feet with a moderate swim risk at many beaches, but some beaches and nearshore areas (particularly between Manistee and Whitehall) could reach 3 to 5 feet with 25 knot gusts at times, a hazard for swimmers and small craft. Scattered thunderstorms could also develop over the lake today. Updated to extend hazard end time past sunset. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement through this evening for MIZ037-043-050- 056. MARINE...Small Craft Advisory until 11 PM EDT this evening for LMZ846>849. && $$ DISCUSSION...CAS/RAH AVIATION...CAS MARINE...CAS