FXUS63 KGRR 091124 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 724 AM EDT Thu May 9 2024 .KEY MESSAGES... - Cooler Temperatures and a Chance of Showers Today - Possible Shower/Storm Saturday and Frost Saturday Night - Low Confidence in Forecast Details Next Week && .DISCUSSION... Issued at 335 AM EDT Thu May 9 2024 - Cooler Temperatures and a Chance of Showers Today A low pressure center in the lower levels of the atmosphere will move across the Ohio river valley region today while a positively tilted upper level trough sinks south over Michigan from northern Ontario. East to northeasterly winds will prevail with mostly cloudy skies. Today will be the start of a few days of cooler than normal temperatures. Trends have continued to reduce the probability of precip throughout the day and also decrease the rain totals over much of the area. The rain associated with the Ohio valley low may stay mainly south of I- 96 with the heavier amounts south of I-94. The HREF 24 hours ago was bullish on 0.5 to 1.0 inch QPF over much of the area, but now 0.5 seems unlikely for most while parts of central Michigan may stay dry. The temperature forecast today has been nudged up slightly, particularly northwest of Grand Rapids where it may reach the mid 60s. Amid the northeast winds, there may be low topped surface-based convective showers developing afternoon-evening between Reed City, Ludington, and Muskegon. Light winds and clearing skies tonight may let temperatures dip into the 30s with a chance of frost in the highlands of interior north- central Michigan, Leota-Tustin area and north. - Possible Shower/Storm Saturday and Frost Saturday Night Shortwave trough arrives Friday night with a clipper-type low bringing showers and a few thunderstorms lingering into the afternoon given the steeper lapse rates. Cool air in northerly flow on the back side of the sfc low results in low temperatures in the upper 30s to lower 40s Saturday night with scattered frost potential in the colder outlying areas. - Low Confidence in Forecast Details Next Week Shortwave ridging on Sunday eventually gives way to another trough Monday with some showers and a few thunderstorms possible along a cold front. There continues to be low confidence with forecast details by the middle of next week as the GFS goes out of phase with the Euro and GEM. There continues to be a general signal for a longwave trough forming across the central/eastern CONUS by late in the week which could bring some showers and storms by Thursday. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 723 AM EDT Thu May 9 2024 Despite rain showers moving in from the south, VFR conditions will prevail today through tonight. Ceilings are expected to be at above 5 kft AGL. East to northeast winds around 10 to 15 knots through this evening turning north to northwest and decreasing to blo 10 knots tonight. && .MARINE... Issued at 335 AM EDT Thu May 9 2024 An east breeze this morning will become north by afternoon with some gusts to 20 knots. The winds near Big and Little Sable Points may be marginally hazardous for small craft this afternoon. Northwest winds on Saturday may build 3-5 foot waves over at least a portion of the nearshore. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ostuno/CAS AVIATION...Ostuno MARINE...CAS