Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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751 FXUS63 KGRR 170510 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 110 AM EDT Mon Jun 17 2024 .KEY MESSAGES... - Thunderstorms Tonight - Hot, humid with occasional thunder this week && .DISCUSSION... Issued at 305 PM EDT Sun Jun 16 2024 - Thunderstorms Tonight The showers and storms across the central and northern zones will move east this afternoon and should be moving east and out of the forecast area this evening. Then we watch an MCV moving through northern Illinois and southern Lake Michigan into our southwest zones with the potential to bring locally heavy rain, hail and high winds overnight across the southern half of the forecast area. SPC marginal risk covers this threat area. - Hot, humid with occasional thunder this week The MCV propagates east and out of the forecast area by Monday morning but is expected to leave behind an outflow boundary across the southern forecast area that could focus some convection Monday afternoon. The HREF has apparently picked up on this idea and now has 70 to 80 percent probabilities of 0.1 QPF in this area on Monday afternoon. We painted an area of higher POPs there but kept them in the 25 to 35 percent range given lack of confidence in the specifics. The Heat Watch was not changed and it still appears that this could be a long duration event where the cumulative effect of high daytime and night time temperatures could necessitate a warning being issued even without warning criteria being met on any one day. There remains uncertainty on extent of convection on Tuesday afternoon, but the the biggest uncertainty remains on Thursday and Friday as a cold front or convective outflow could modify temperatures across the northern half of the forecast area. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 110 AM EDT Mon Jun 17 2024 Lingering showers and thunderstorms at our southeast terminals at the moment will gradually end during the next few hours. Primarily VFR conditions are then expected at the terminals overnight but some patchy MVFR fog will develop toward daybreak. Any patchy fog will burn off by mid morning with VFR conditions expected for the rest of the day. Isolated showers and thunderstorms are possible in the afternoon and evening but there is not enough potential or confidence in timing to warrant mention in the terminal forecasts at this time. && .MARINE... Issued at 305 PM EDT Sun Jun 16 2024 No changes to the SCA or CFW. Current forecast on track with southerly winds driving some higher waves from Grand Haven north with structural and longwave currents making swimming dangerous. Winds and waves could be locally higher in thunderstorms this evening south of Muskegon. Winds and waves will decrease slightly on Monday as the sfc pressure gradient slackens a little, but the night shift can evaluate this and determine if small craft and swim conditions will improve enough for the SCA and CFW to expire at 2 am or have to be extended. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until 2 AM EDT early this morning for MIZ037-043-050-056. Air Quality Alert until midnight EDT tonight for MIZ037-043-050- 056-064-071. Excessive Heat Watch from noon EDT today through Friday evening for MIZ043>046-050>052-056>059-064>067-071>074. MARINE...Small Craft Advisory until 2 AM EDT early this morning for LMZ847>849. && $$ DISCUSSION...Ostuno AVIATION...Laurens MARINE...Ostuno