Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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840 FXUS63 KGRR 251140 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 740 AM EDT Tue Jun 25 2024 .KEY MESSAGES... - Early Morning Potential for Severe Thunderstorms - Strong Storms Possible This Afternoon - Additional Showers Early Wednesday - Fair weather Thursday then showers and storms Friday/Saturday && .DISCUSSION... Issued at 241 AM EDT Tue Jun 25 2024 - Early Morning Potential for Severe Thunderstorms Much of the forecast remains unchanged while we monitor the cluster of storms currently tracking through northern Wisconsin that will arrive in lower Michigan within a few hours. As expected, these storms continue to evolve into a MCS/squall line with a projected time of arrival into West Michigan around 4 to 6am. This will largely be a game of monitoring our environment to estimate the persistence of storms and whether they decay or prevail. Within the Enhanced Risk upstream of lower Michigan, these storms are thriving and will evolve in an environment with 3000- 5000J/kg MUCAPE and 50+ knots of Bulk Shear. As the surface low progresses further east, warm and moist advection will surge ahead of the storms supporting some ongoing strength. We will not be as unstable as areas to our west, but a favorable kinematic environment will support ongoing convection as storms move onshore and progress east through mid morning. Storms will gradually enter a weakening stage the further east they progress into lower Michigan. Damaging wind gusts remain the primary concern as storms move onshore this morning, but some hail may also occur. - Strong Storms Possible This Afternoon The potential for thunderstorms or new convection late tonight will be dependent on evolution of storms this morning. That is to say, wherever the frontal boundary sets up is where the best chance for renewed convection will occur. The strong low- level jet will weaken as it pivots further south late this morning to early afternoon, but instability rebounds and may support the risk for renewed thunderstorms with a damaging wind gust and hail potential. The main threat area will be near and south of I-96. - Additional Showers Early Wednesday Another trough and cold front will sweep through the area Wednesday morning bringing chance for showers during the first half of the day. High pressure will fill in during the second half of the day and into Thursday. - Fair weather Thursday then showers and storms Friday/Saturday The flow regime across the Great Lakes this week into next week features an enhanced belt of westerlies across the northern CONUS in between subtropical ridging across the southern CONUS and an upper low across central Canada. Occasional shortwave troughs embedded in the flow will bring rain chances every couple of days from this weekend into early next week. Surface high pressure brings fine summer weather for Thursday into early Friday before moving east with warm advection pattern developing by Friday morning. Moisture advection is also increasing with rain chances by Friday morning as moisture pools ahead of the the next trough. THere remains some ensemble spread on timing and and depth of the trough but the consensus has the greatest chance for showers and storms for late Friday night. A severe weather threat is possible late Friday night into early Saturday as Lower Michigan is in the warm sector and model soundings show 30 to 35 knots of shear ahead of the cold front. Surface high builds in behind the front with fair weather for Sunday into Monday. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 740 AM EDT Tue Jun 25 2024 Squall line with downburst winds in the 40 to 50 knot range moving through AZO, BTL, LAN and JXN through 13Z then lingering showers and thunderstorms through about 14-15Z. Wind directions and speeds will be highly variable this morning due to the effects of thunderstorm outflows and lingering effects of the cold pool of air left in the wake of the storms. General winds from the southwest and west will be established by this afternoon. Areas of IFR in the lines of storms across southern Lower Michigan will move out and give way to VFR conditions by late morning into the afternoon. && .MARINE... Issued at 241 AM EDT Tue Jun 25 2024 Strong southerly winds early this morning bring waves to hazardous levels for Small Craft and beaches. Strong thunderstorms currently in northern Wisconsin will cross Lake Michigan early this morning bringing significant winds and also a chance for large hail. Additional showers and storms possible this afternoon into the evening, and again Wednesday morning. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement through this evening for MIZ037-043-050- 056-064-071. MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ844>849. && $$ DISCUSSION...Ostuno/Thielke AVIATION...Ostuno MARINE...Thielke