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Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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081 FXUS63 KGRR 300715 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 315 AM EDT Sun Jun 30 2024 .KEY MESSAGES... - Cooler Today and Monday With Much Less Humidity - Potential for Thunderstorms Late Tuesday into Early Wednesday && .DISCUSSION... Issued at 315 AM EDT Sun Jun 30 2024 - Cooler Today and Monday With Much Less Humidity Today and Monday`s weather will be governed by synoptic scale ridging and surface high pressure that will translate eastward through the Midwest and Great Lakes. Following Saturday night`s cold frontal passage, cold air advection this morning is ushering in 850 mb temperatures by 18Z that are at least 10 Celsius cooler than 24 hours ago. The feel of humidity will be drastically lower today compared to yesterday, with dew points no longer around 70 F but instead around 50 F. Partly cloudy skies this morning with stratocumulus should give way to plenty of sunshine by afternoon as much drier midlevel air infiltrates into the diurnal PBL. - Potential for Thunderstorms Late Tuesday into Early Wednesday A southwesterly low level jet moves into the CWA during the day on Tuesday. This feature will advect in a moist and unstable airmass by the afternoon. PWAT`s are progged to climb up to around 2 inches Tuesday night. A weakening cold front is shown to push down from the northwest later Tuesday night or early Wednesday morning with scattered to numerous showers/storms forming out ahead of it. Models are in relative agreement on this scenario. Ensemble QPF trends still support higher POP`s during this period as most members are showing measurable QPF. Ensemble wind gusts from the GFS and ECMWF have a signal for gusty conditions as well. Values over 25 knots are looking possible. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 118 AM EDT Sun Jun 30 2024 A cold front will push south of the TAF sites in Lower MI over the next few hours. Some MVFR clouds were slipping down from the north and it appears they will impact the TAF sites for a few hours this morning. As the atmosphere dries out later this morning and into the afternoon, the clouds will break up leading to mostly clear conditions. Occasional gusts over 20 knots will be possible through the day, from the north northwest. && .MARINE... Issued at 315 AM EDT Sun Jun 30 2024 Small Craft Advisory and Beach Hazards Statement for dangerous swimming conditions along Lake Michigan today as north winds 20 to 25 mph build waves 4 to 7 feet. The hazards are likely to persist till around sunset today, though may end a little sooner around Ludington and a little later around South Haven to St Joseph. The strong north winds may also cause upwelling of colder water at some beaches that would linger into Monday. (This upwelling is due to a net westward transport of water during strong north winds due to the Ekman Spiral, a consequence of the Coriolis effect.) && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement through this evening for MIZ037-043-050- 056-064-071. MARINE...Small Craft Advisory until 10 PM EDT this evening for LMZ844>849. && $$ DISCUSSION...CAS/MJS AVIATION...MJS MARINE...CAS