Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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024 FXUS63 KGRR 082346 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 746 PM EDT Wed May 8 2024 .KEY MESSAGES... - Rain Thursday - Rain Expected Saturday - Lower Certainty Pattern Into Next Week && .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 /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 741 PM EDT Wed May 8 2024 A storm system will track in from the west later tonight and persist into Thursday afternoon. The low levels are projected to struggle saturating early on so we will keep conditions at VFR. However as the rain picks up in intensity, mainly for the southern TAF sites of KAZO, KBTL and KJXN, the visibility could come down to MVFR levels. During the afternoon hours as the region ends up on the backside of the departing storm system, condition should return to VFR levels. Overall the area will be on the north side of this wave so the winds will be out of the east. && .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. && $$ DISCUSSION...04/Thomas AVIATION...MJS MARINE...04