871 FXUS63 KGRR 061048 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 648 AM EDT Thu Aug 6 2026 .KEY MESSAGES... - Areas of Fog this Morning - 20 to 30 Percent Chance for Showers and Thunderstorms Today - Additional Rain and Thunderstorm Chances Friday into Next Week && .DISCUSSION... Issued at 313 AM EDT Thu Aug 6 2026 - Areas of Fog this Morning Residual moisture from rain over the past 24 hours, clearing behind the showers in eastern Michigan, along with fog that has developed over the cooler waters of Lake Michigan will bring reduced visibility to portions of western Michigan this morning. Lowest visibilities of 0 to 1/2 mile are along Lake Michigan south of Grand Haven. Expect these lower visibilities to continue into Thursday morning before improving within a few hours of sunrise. Fog is not expected to be as dense further inland but could see some spots drop down to 1 mile. Make sure to give yourself extra time for the morning commute and use your low-beam headlights. - 20 to 30 Percent Chance for Showers and Thunderstorms Today Overall Thursday morning could remain largely dry with a diurnal trend for showers and thunderstorms today. There will also be some support with upper level divergence and a 500mb shortwave passing to the north during the afternoon. Showers and thunderstorms will be isolated to scattered during the afternoon and early evening before the inversion builds in. Instability builds to around 1000 J/kg this afternoon and with marginal shear around 25 knots. With these variables not expecting severe storms, but the strongest storms could contain small hail and gusty winds. - Additional Rain and Thunderstorm Chances Friday into Next Week Overall the large scale pattern remains stationary with the upper level low anchored over the Hudson Bay. What that means for us is troughing remains overhead with multiple shortwaves moving through into next week. With each disturbance in our moist environment, showers and thunderstorms will be possible. However, there are differences with the timing and track of each of these shortwaves. This brings higher uncertainty with when and where the best chances will be. At this time there is better agreement for Friday into Saturday. Friday looks to be a rinse and repeat of today with some diurnal showers and thunderstorms during the afternoon and early evening. A quick moving front tracks through the area Friday night into Saturday morning bringing another 20 to 30 percent chance for showers and thunderstorms. Afterwards confidence quickly decreases, but no one day looks like a washout as each shortwave quickly moves through. Additionally between the different severe weather outlook models, severe weather doesn`t look likely over the next week. Confidence should increase as we get closer, but it may be an pattern where we have to take it day by day. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 648 AM EDT Thu Aug 6 2026 LIFR to IFR ceilings this morning will lift to VFR between 13Z to 16Z. Showers and thunderstorms this afternoon will be hit and miss with probabilities around 20 to 30 percent. With confidence not high that terminals will be impacted, kept the mention in a Prob30 group. Heavy rain will be possible with any thunderstorm. Toward the end of the forecast ceilings and visibilities may lower to MVFR. && .MARINE... Issued at 313 AM EDT Thu Aug 6 2026 Dense fog has developed largely south of Grand Haven this morning. A Marine Dense Fog Advisory is in effect until 10am. Fog may expand further north before clearing. Winds will remain light and variable through the day, but will become more westerly as the lake breeze develops this afternoon. Pop up showers and thunderstorms will be possible during the afternoon and early evening, but the best chances (20 to 30 percent) will be over land. Friday winds will be more southerly wind thunderstorms chances remaining over land until late Friday night. Several chances for rain and storms are expected over the weekend into next week, but confidence is low in when and where chances are best. Winds may approach Small Craft Advisory levels Monday, but overall winds and waves are expected to remain below Small Craft Advisory and Beach Hazard Statement levels. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Dense Fog Advisory until 10 AM EDT this morning for LMZ844>846. && $$ DISCUSSION...RAH AVIATION...RAH MARINE...RAH

NWS GRR Office Area Forecast Discussion