160 FXUS63 KGRR 011749 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 149 PM EDT Sat Aug 1 2026 .KEY MESSAGES... - Showers ending Sunday - Dry early next week, then chances for rain. && .DISCUSSION... Issued at 312 AM EDT Sat Aug 1 2026 - Showers ending Sunday Regional radar shows a large area of showers over the cwa extending south to the Tennessee Valley. No big changes to the forecast planned for today. A slow moving low pressure system over central IL will continue to produce light to occasionally moderate rain today, tonight and ending from northwest to southeast Sunday. Instability isn`t high, but there is enough SBCAPE to keep the mention of thunder in the forecast. Precipitable water values remain somewhat high...around 1.75 inches, which suggests that a stronger shower or storm could produce heavy rainfall; the far southern cwa remains in a slight risk for excessive rainfall. Overall, basin QPF ranges from a third to around an inch. Thus, while there may be localized flooding, widespread river flooding isn`t expected. Heaviest rainfall will occur this afternoon as deformation forcing develops. The upper trough axis will pass through the cwa Sunday morning, which should push the precipitation east; much of the cwa will be dry by Sunday afternoon. - Dry early next week, then chances for rain. High pressure will begin building into the region Sunday night and continue through Tuesday; we`ll be dry through that time period. Highs will be in the mid 80s and lows in the mid to upper 50s; dewpoints will also be in the 50s. Thus, lower humidity is expected early in the week. Troughing then develops late in the week and we could see several low chances for additional precipitation. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 149 PM EDT Sat Aug 1 2026 There is a mix of VFR/MVFR/IFR out there with cloud ceilings and showers associated with a slow-moving low pressure system that is centered over Illinois. In general, can plan on prevailing MVFR today and IFR tonight into Sunday morning. The main concern for the rest of this afternoon is the potential for a band or two of heavier rain showers, possibly with an embedded thunderstorm, with IFR visibility. Presently there is one such isolated thunderstorm in the vicinity of OZW (Howell). Models have been favoring the vicinity of LAN for the greatest potential for a heavy rain shower or TS over the next several hours, but other aerodromes could also get in on heavier showers temporarily. && .MARINE... Issued at 312 AM EDT Sat Aug 1 2026 Northeast winds will increase to 15 to 20 knots today resulting in highest waves near the 5 mile point offshore. Winds increase a bit to 15 to 25 knots tonight and a small craft advisory may be needed. Otherwise, chances for thunderstorms, while not zero, are minimal given the best instability with this system remains south of the lake. Waves are likely to increase again Sunday afternoon as high pressure builds over the Great Lakes and an advisory may be needed then too. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...04 AVIATION...CAS MARINE...04

NWS GRR Office Area Forecast Discussion