594 FXUS63 KGRR 152328 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 728 PM EDT Sat Aug 15 2026 .KEY MESSAGES... - Chance of showers and isolated thunderstorms through Sunday - Drier and less humid through early part of week - Another frontal system could bring showers and storms midweek && .DISCUSSION... Issued at 144 PM EDT Sat Aug 15 2026 - Chance of showers and isolated thunderstorms through Sunday Light showers are all that is currently moving through the region as quasi stationary front continues to keep a weakening MCV south of Michigan. The stable air over southern Michigan should continue to stifle convection. As a SFC low moves eastward this afternoon and evening it could move north enough to allow for scattered showers and isolated storms along the I -94 corridor. The shear and CAPE remain through IN and Ohio so the threat of severe from any storms to forms continues to diminish. Any showers and storms that form will be aided by the humid air mass and heavy rainfall will be possible. A short upper level wave and a deepening mid level trough will swing a frontal system through the area tomorrow. This could allow for another chance for showers tomorrow morning into early afternoon. While lapse rates aren`t great and the front is coming at the wrong time of day for convection, there should be sufficient CAPE and PWATS are upwards of 2 inches from latest CAMS. So any showers or storms that do form could have periods of heavy rain. - Drier and less humid through early part of week The front will move through tomorrow with cooler and drier air in its wake which will drop Temps and dewpoints down to normal making the are more comfortable. Max temperatures will be near normal, in the low 80s, through Tuesday. - Another frontal system could bring showers and storms midweek The quasi stationary high that was sitting over the south and allowed for all the weather to move through Illinois and Indiana this past week will shift to the west. This upcoming week will be dominated by a large upper level low that will build over the Hudson Bay. A it treks to the east will should move south over northern Ontario and a cold front extending from it should move from the northwest, across Michigan and sweep into the mid Atlantic by Thursday. There is some question on timing but currently, there is the potential for showers and storms Tuesday night into Wednesday. This should also clear temperatures off for the latter half of this upcoming week. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 721 PM EDT Sat Aug 15 2026 Light showers are falling over the southern terminals and visibilities have reduced to around 2 miles. A scattered IFR deck has also appeared; we`ll see other terminals become IFR/LIFR overnight. MKG/GRR might not see much rain overnight. More likely the showers will remain south of I-96. Improving conditions will develop Sunday afternoon. && .MARINE... Issued at 149 PM EDT Sat Aug 15 2026 Offshore flow will continue through today and into tomorrow which will keep winds and waves low in the nearshore. Larger waves will build as they move westward in the open waters. Showers are storms are possible early Sunday and a cold front will shift winds to the north tomorrow night, with building waves in the open waters while waves should remain between 1 to 3 feet in the nearshore. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ceru AVIATION...04 MARINE...Ceru

NWS GRR Office Area Forecast Discussion