Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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364 FXUS63 KGRR 050014 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 814 PM EDT Sat May 4 2024 .KEY MESSAGES... - A few showers,maybe some thunder this evening, quiet Sunday - Dry Monday, then chances for showers/storms && .DISCUSSION... Issued at 255 PM EDT Sat May 4 2024 - A few showers,maybe some thunder this evening, quiet Sunday Showers/thunderstorms will try to get their act together this afternoon in Illinois and Wisconsin will move across Lake Michigan and western Indiana early this evening along with a weak cold front. Models are indicating this line will struggle to remain organized as it moves east and considering decreasing elevated instability overnight - it is looking more like a broken weakening line of showers/thunderstorms that may result in quite a bit of the area seeing no rain at all. If any storms do hold together, not out of the question that some small hail will be possible though this doesnt look that likely at this time. Any lingering light showers should be off to the east by daybreak Sunday. High pressure begins to build in Sunday with stubborn cloud cover lingering through much of the day. This could result in cooler temperatures than Saturday but dry weather should result regardless. - Dry Monday, then chances for showers/storms Transient high pressure over Lower MI Monday will produce sunny skies and mild temperatures with highs around 60. An upper low over the northern Plains will influence our wx the rest of the week as pieces of energy will rotate through the flow and move across the region. Clouds will increase Monday night with storms likely Tuesday when a warm front lifts north late in the day. Moderately strong dynamics look to be develop late Tuesday as a LLJ moves over the region and a mid level speed max aims at Lower MI from the southwest. H85-h5 lapse rates also climb to around 7c/km during this time frame. Given the warm frontal interaction, strong shear and decent helicity, all forms of severe wx look to be possible from late Tuesday afternoon through Tuesday evening; SPC has highlighted the southwest cwa for a severe wx risk. Once the warm front moves through late Tuesday night there may be a lull in precipitation until the next wave over the central Plains moves toward the region late Wednesday through Thursday night. More showers/storms are expected then. The upper low isn`t progd to move through the state until late Saturday, so unsettle conditions will continue through the first half of the weekend. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 814 PM EDT Sat May 4 2024 Still expect a relatively narrow band of showers to traverse the terminals overnight followed by IFR ceiling restrictions that slowly climb to MVFR after 12Z. Guidance suggests that brief LIFR ceiling restrictions lasting on the order of an hour or so will be possible at many of terminals, presumably associated with the passage of the cold front. This idea is not supported by all of the available guidance nor is timing certain. Hence, did not attempt to represent this quick departure in the terminals. Did include a brief window of VCTS for the KAZO terminal based on ongoing activity upstream near Chicago. VCTS may be required before 03Z at MKG as well. However, current expectations are for thunderstorms over Lake Michigan to weaken or dissipate prior to reaching eastern Lake MI, which is why we were reluctant to include VCTS at MKG just yet. There is a lesser, but nonzero, chance of needing to include VCTS at GRR later tonight in the 05Z timeframe. && .MARINE... Issued at 300 PM EDT Sat May 4 2024 Winds this evening still expected to nudge up this evening as a cold front works across Lake Michigan. A few showers and some thunder possible but showers/storms should be weakening as they approach the shoreline. Behind the front north/northwest flow should increase a little but at this time looks like it should peak out 15-20kts and will continue to hold off on an advisory. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...04/Maczko AVIATION...TJT MARINE...Maczko