Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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836 FXUS63 KGRR 281616 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 1216 PM EDT Fri Jun 28 2024 .KEY MESSAGES... - Increasing Showers and Storms Tonight into Saturday - Cool High Pressure Sunday/Monday - Rain chances mid/late week && .UPDATE... Issued at 1215 PM EDT Fri Jun 28 2024 High pressure is situated off to the east of the Great Lakes across Southern New England and the Middle Atlantic states at midday. Low pressure is located upstream with a low in Minnesota. Ceilings are still high base across Western Lower Michigan with most sites reporting 9,000 feet or higher. South Haven and Grand Rapids are both reporting some light rain, but we are not even seeing the pavement turn wet here at the office due to how light the precipitation is. We will likely continue to see some light rain try to advect in from the west this afternoon especially over the southwest CWA towards South Haven and Covert. The precipitation is associated with a warm front aloft and a shortwave in the mid levels moving our direction from Iowa. 850mb dew points rise from below 0C earlier this morning to around +12C this afternoon. That moisture flux is resulting in instability and an increase in precipitation ahead of the shortwave. Bottom line a mainly cloudy afternoon with increasing chances for rain showers. Highs in most areas will hold in the 70s. && .DISCUSSION... Issued at 335 AM EDT Fri Jun 28 2024 - Increasing Showers and Storms Tonight into Saturday Lingering surface high pressure keeps conditons quiet this morning while focus turns to this afternoon and into Saturday for showers and storms. Starting this afternoon, mid-level shortwave energy embedded in ridging will trigger increasing shower activity. Low level profiles look quite dry, so wouldn`t expect too much precipitation to reach the surface and a few "virga showers" across the area. Profiles moisten up into Saturday morning as the parent low moves across southern Ontario and a trailing cold front approaches. As a secondary low develops along the southern edge of the front south of the state line, a warm front will lift north and trigger elevated showers across southern Michigan early Saturday. Diurnal instability will build into the early afternoon ahead of the lagging cold front. Favorable deep-layer shear will support at least an isolated severe thunderstorm threat Saturday afternoon and evening as the cold front sweeps through. Damaging wind gusts and hail will be the primary hazards to monitor for. - Cool High Pressure for early Next Week Upper troughing with Canadian surface high building overhead will provide dry and cool weather for Sunday into Monday. Lows Sunday night expected to dip down into the 40s in the rural areas and even some upper 30s in the cold hollows. The surface high moves east on Tuesday with warm advection and moisture return ahead of the next shortwave trough. - Rain chances mid/late week Shortwave ridging late Monday into Tuesday is flattened and replaced by low amplitude troughing on Wednesday, which persists the rest of the week. Low confidence in the timing/details of rain given individual model and ensemble spread but the general consensus is that a cold front will bring showers and thunderstorms late Tuesday night into Wednesday with the front hanging up just south of Lower Michigan and another surface low forming along this baroclinic zone by the Fourth of July. At this point it looks like bulk of showers and storms may remain just to the south of Lower Michigan after Wednesday but chance POPs in the forecast will cover the potential for the front/sfc low to move further north. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 732 AM EDT Fri Jun 28 2024 VFR conditions will continue into this evening then areas of MVFR will develop tonight as rain showers become more widespread along with ceilings in the 1500 to 2500 feet AGL range. Southeast winds will gust to near 20 knots today. There could be a thunderstorm overnight but coverage is low enough to leave out of the forecast for now. && .MARINE... Issued at 335 AM EDT Fri Jun 28 2024 Wind shifts southerly this morning and builds. Waves will increase and will become hazardous to small craft after daybreak. A moderate swim risk is expected for beaches north of Grand Haven. A small craft advisory remains in place for Muskegon, Mason, and Oceana Counties, and wave heights will need to be monitored for potential Beach Hazards Statement. Southerly winds will make beaches on the south side of south piers especially vulnerable to structural currents and turbulent waves. For today this will include Grand Haven State Park and Pere Marquette Park in Muskegon. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory until 2 AM EDT Saturday for LMZ847>849. && $$ UPDATE...Duke DISCUSSION...Ostuno/Thielke AVIATION...Ostuno MARINE...Thielke