Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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242 FXUS63 KGRR 090532 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 132 AM EDT Thu May 9 2024 .KEY MESSAGES... - Rain Thursday - Rain Expected Saturday - Lower Certainty Pattern Into Next Week && .UPDATE... Issued at 926 PM EDT Wed May 8 2024 Trends in the latest HRRR suggest this dry air currently in place will play a more significant role in the timing and amount of precipitation we end up seeing. Through 12z, there`s almost no qpf seen in the CWA. Based on this, I trended POPs downward for tonight and also shifted them further south, closer to the moisture. && .DISCUSSION... Issued at 254 PM EDT Wed May 8 2024 - Rain Thursday Clear skies this evening will give way to increasing clouds tonight as low pressure over Oklahoma begins to get caught up in the upper flow over of the northern MS Valley trough. Given the east-west elongated nature of the trough, it will take at least 24 hrs for the low and its precipitation to move out of the cwa. Model trends track the low across the north side of the OH Valley tomorrow developing rain in the far southern cwa around 12z and then moving north. Little in the way of instability means thunder should stay south of the cwa. QPF totals have trended down a bit and range from a couple of hundredths near US-10 to around a half in near I-94. Light rain will end Friday evening. Below normal temperatures are expected Thursday with highs in the upper 50s. There could also be some patchy frost in low lying areas near US-10 Thursday night as temperatures fall into the upper 30s there. - Rain Expected Saturday Friday brings dry weather to West Michigan as high pressure and ridging aloft shifts through the Central Great Lakes. It will be slightly cooler than normal with highs in the low to mid 60s. Our next chance of rain begins early Saturday as a shortwave drives a surface low across the region. Rain showers are expected with the best coverage Saturday morning as the low itself crosses the area. However, some diurnal enhancement on the backside of the low is possible Saturday afternoon as the upper-level cold pool passing overhead given steep mid-level lapse rates in the 7C-8C range. If we can get a shower with a better updraft, those lapse rates suggest that isolated thunderstorms are possible. - Lower Certainty Pattern Into Next Week Dry weather is expected for the day on Sunday as a brief period of shortwave and upper-level ridging slides through the state. Precipitation chances do increase somewhat Monday as a shortwave and cold front enter the region, however the timing and placement of these features is uncertain. Ensemble means and deterministic guidance do suggest a longwave trough develops but there remains notable spread in model guidance as to the specifics of how the pattern evolves. This gives lower confidence as to forecast details in the days 5-7 timeframe. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 132 AM EDT Thu May 9 2024 VFR conditions will prevail through Thursday evening. Showers will move in from the south during the morning but ceilings are expected to stay above 5 kft AGL. East to northeast winds 10 to 15 knots through tonight. && .MARINE... Issued at 254 PM EDT Wed May 8 2024 East winds will develop tonight and could be gusty for a brief period during the late morning/early afternoon Thursday but will hold off on a headline due to the limited nature of it. Colder air moving southeast early Saturday may result in 3-5 foot waves south of Grand Haven for a period as well. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...MJS DISCUSSION...04/Thomas AVIATION...Ostuno MARINE...04