Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000 FXUS63 KGRR 271128 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 728 AM EDT Thu Jul 27 2017 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 321 AM EDT Thu Jul 27 2017 A cold front will move through Lower Michigan today with only scattered showers and thunderstorms then drier conditions can be expected into the weekend as high pressure builds in. && .SHORT TERM...(Today through Saturday) Issued at 321 AM EDT Thu Jul 27 2017 Forecast issues in the near term are for POPs today as cold front moves through with a few showers and thunderstorms, then the potential for some diurnally enhanced showers and isolated thunderstorms on Friday as upper low comes through. For today, showers across the northern forecast area early this morning will gradually move south this morning and forecast soundings show enough instability for thunderstorms across the central and southern zones through the day. Drying behind the front begins this evening with showers ending across the southern zones by midnight. Heights fall and lapse rates steepen on Friday morning as an upper low moves across the central Great Lakes with showers and thunderstorms diurnally enhanced into the afternoon. Superblend POPs seemed a bit low given the good model agreement on the strength of this feature and were adjusted up and if trends continue could be bumped up further in the future. The upper low departs Friday night with strong sfc ridging and height rises meaning dry weather Friday night and Saturday. .LONG TERM...(Saturday night through Wednesday) Issued at 321 AM EDT Thu Jul 27 2017 A high pressure ridge will continue in control of the wx pattern Saturday night through Sunday night and bring fair wx with seasonable temperatures. High temps Sunday will reach 80 to 85 degrees with min temps mainly in the 50`s. The overall wx pattern continues to look quite dry through next week as a high pressure ridge will continue to dominate the wx pattern. A weak cold front moving in from the northwest will bring a chance for a few showers and storms by late Wednesday or Thursday but significant rainfall is unlikely as this system will have very little moisture to work with. Temps will continue to average near normal through the long range fcst period. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 728 AM EDT Thu Jul 27 2017 VFR conditions expected through tonight. A few showers and thunderstorms are possible through the afternoon with brief MVFR and IFR conditions possible. The chances were too low to include in the forecast. Winds will go north to northeast at less than 10 knots later today and this evening. && .MARINE... Issued at 321 AM EDT Thu Jul 27 2017 North winds to 20 knots will build waves to 2 to 4 feet across the nearshore waters north of Whitehall by late this afternoon. Some 3 to 5 foot waves are possible near Little Sable and Big Sable points this afternoon. Winds and waves will decrease overnight. && .HYDROLOGY... Issued at 324 PM EDT Wed Jul 26 2017 Thunderstorms rolling along the US-10 / M-20 corridors early this afternoon have produced rainfall amounts between a half to one inch. Given PW values around 1.75 inches in that area, any convection will have efficient rainfall rates. Additional storms developing upstream in Wisconsin will affect some of the same areas through this evening. Much of the area has been dry over the last two weeks, so this rain is beneficial. WPC indicates only a marginal risk of excessive rainfall, and it is easy to agree with that. There is chance of showers and storms in the southern portion of Lower Michigan Thursday into Friday morning, but the questionable coverage of convection will keep the risk of excessive rain very low. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ SYNOPSIS...Ostuno SHORT TERM...Ostuno LONG TERM...Laurens AVIATION...Ostuno HYDROLOGY...CAS MARINE...Ostuno

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