095 FXUS63 KGRR 150728 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 328 AM EDT Sat Mar 15 2025 .KEY MESSAGES... - Storms early this morning, then warm and windy - 30 degrees colder Sunday with rain mixing with snow - Warm mid week, then colder && .DISCUSSION... Issued at 328 AM EDT Sat Mar 15 2025 - Storms early this morning, then warm and windy Regional radar shows a mature cyclone over Iowa with a broad band of convection stretching from northern WI to near CHI south to MEM. A strong LLJ accompanies this convection and strong winds are reaching the surface as the convection moves through; numerous severe wind gusts have been reported upstream. The question is whether we`ll see severe wind gusts here early this morning. The answer is probably not. Latest mesoanalysis shows 1000 j/k MUCAPE has decreased to half of that and is forecast to continue to decrease the rest of the night as the precipitation moves over the cwa. That`s likely a good thing since KGRR 88D VWP shows 65kts at 4k ft. If a stronger thunderstorm develops, then we may see a severe wind gust. However, it`s most likely going to be isolated early this morning. Once this band of convection moves through, better mechanical mixing will develop as skies clear a bit. BUFKIT shows mixing into 55-60kt winds today. All of the wind potential probably won`t be realized but we could certainly see some winds in the 50-55 mph range today; the wind advisory remains in effect. Another upper trough will move northeast toward Lower MI this afternoon in conjunction with a surface wave riding up the cold front. Given the winds aloft and the expected uptick in instability, severe winds will be a possibility mainly southeast of a MOP to LWA line during the late afternoon/early evening; SPC has maintained the marginal risk for that area. - 30 degrees colder Sunday with rain mixing with snow Once the cold front moves through tonight, colder air will flow back into the cwa. H8 temps are expected to fall from +10c to -10c by 18z Sunday. We`re looking at rain in the morning that will mix with and turn to snow showers as the precipitation winds down during the afternoon. Highs today are expected around 70 and only around 40 Sunday. - Warm mid week, then colder The Spring roller coaster will continue this week. Another lee side low will develop as a strong wave crosses the Rockies Wednesday. Strong southwest flow ahead of it will push temperaturesinto the mid 60s Tuesday and Wednesday before a cold front moves through and drops highs back into the 30s Thursday and Friday. This will be another event where we see rain mix with and change over to snow before ending. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 145 AM EDT Sat Mar 15 2025 LLWS of 50 to 55 knots will continue overnight. Surface winds will gust over 40 knots with a line of showers and thunderstorms moving across southern Lower Michigan between 07Z to 10Z. Then widespread wind gusts over 35 knots are expected from 12Z to about 20Z. Showers and thunderstorms will return this evening bringing some IFR conditions across central and eastern Lower Michigan including LAN and JXN after 00Z, && .MARINE... Issued at 328 AM EDT Sat Mar 15 2025 Strong winds are expected today and the Gale Warning will go into effect at 8 AM. South gales will gust to 45 knots today resulting in 5-8 foot waves. A Small Craft Advisory will be needed later this evening once the Gale Warning ends. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Wind Advisory until 8 PM EDT this evening for MIZ037>040-043>046- 050>052-056>059-064>067-071>074. MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ844>849. Gale Warning from 8 AM this morning to 8 PM EDT this evening for LMZ844>849. && $$ DISCUSSION...04 AVIATION...Ostuno MARINE...04

NWS GRR Office Area Forecast Discussion