446 FXUS63 KGRR 102323 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 723 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 00Z TAFS through 00Z Thursday evening) Issued at 719 PM EDT Wed Oct 10 2018 Low IFR clouds and impactful showers may be possible until the cold front comes through from west to east later this evening. The wind will shift behind the front and ceilings should settle into the MVFR category. Gusty winds are expected...especially behind the front with some values over 25 knots possible. As we go through the day on Thu...a trend toward VFR looks likely as drier air gradually filters in. && .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...Small Craft Advisory until 10 PM EDT this evening for LMZ844>849. Gale Warning until 1 PM EDT Thursday for LMZ844>849. && $$ SYNOPSIS...Ostuno DISCUSSION...Ostuno AVIATION...MJS HYDROLOGY...AMD MARINE...Ostuno