490 FXUS63 KGRR 110308 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 1108 PM EDT Wed Oct 10 2018 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 327 PM EDT Wed Oct 10 2018 A cold front will come through tonight bringing widespread rains that will taper off after midnight. Much cooler air will move in with frosty temperatures over the weekend and into early next week. && .DISCUSSION...(This evening through next Wednesday) Issued at 327 PM EDT Wed Oct 10 2018 Severe weather threat this evening is low despite 40 to 50 knots of deep layer shear due to lack of instability. Narrow cold frontal rainband currently taking shape across central Illinois may extend north close to the southern Michigan border but threat of strong winds or QLCS tornadoes looks to be quite limited thanks to stabilizing effect of clouds and rain out ahead of it. The front goes through tonight with sharp temperature and dew point drop overnight. Strong cold air advection through Thursday means little diurnal rise in temperatures with temperatures probably stuck most of the day in the upper 40s to lower 50s. This, combined with winds and lake effect clouds will make for quite a shock from the previous three days of summer-like weather. After some lake effect clouds and showers on Thursday we expect a dry weather period with some frost/freeze potential for Thursday night and Friday night. The extent of clouds is the problem, with forecast moisture profiles showing an inversion around 5 kft that could result in a thin stratus deck persisting for Thursday night and possibly Friday night. The airmass is cold and any clearing would result in frost formation as well as some freezing temperatures. A northern stream shortwave trough comes through Saturday night with a reinforcing shot of cold air for Sunday and Monday. If moisture is deep enough into the DGZ there could be some snow or graupel on Sunday night. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1108 PM EDT Wed Oct 10 2018 West/northwesterly winds will gust 20-25 kts through much of the TAF period at all TAF sites though a few gusts may approach or exceed 30 kts from 06/08Z. A rather solid stratus deck rooted around 2500 ft will take hold across the area tonight and transition to broken lake- effect cloud cover by midday Thursday, still generally rooted between 2000-2500 ft. Light lake effect rain showers are possible at MKG all day with patchy drizzle at AZO/BTL/GRR. && .MARINE... Issued at 327 PM EDT Wed Oct 10 2018 No changes for the Gale Warning although this event will be marginal and winds may stay below gales for much of the time. Waves are still expected to build over 6 feet on Thursday. && .HYDROLOGY... Issued at 1235 PM EDT Wed Oct 10 2018 Rain has moved back into the area from the south. Since yesterday, the threat for widespread heavy rain (enough to cause river flooding) has continued to decrease. Generally, between 0.5 and 1.0 inches of rain is likely across most of the area over the next 12 hours. Since the current airmass is loaded with plenty of moisture, we will need to keep a close eye on rainfall rates at individual locations (especially urban areas) in case any thunderstorms track over the same locations repeatedly, which could cause localized flooding/drainage issues. Otherwise, it looks like the area will shift into fall mode for the next several days at least as this hot, humid, and wet weather pattern moves off to the east and away from our area. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Gale Warning until 1 PM EDT Thursday for LMZ844>849. && $$ SYNOPSIS...Ostuno DISCUSSION...Ostuno AVIATION...Borchardt HYDROLOGY...AMD MARINE...Ostuno