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Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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255 FXUS63 KGRR 111709 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 109 PM EDT Sun Aug 11 2024 .KEY MESSAGES... - Fair weather today through Monday - Dry through midweek; better support for late-week rain && .UPDATE... Issued at 1137 AM EDT Sun Aug 11 2024 We expanded the mention of an isolated shower today for inland areas. Satellite imagery shows clouds developing along the I-94 corridor and radar suggests there could be a rain shower or two in that region. Thus we added that mention to the forecast. SPC`s meso page does show MU CAPE values off 500-1000 J/kg inland. The latest HRRR develops isolated showers inland this afternoon so we expanded the mention of isolated showers even for Lansing, Alma and Mt Pleasant. Conditions on the lakeshore were marginally hazardous at this time. The wind was on the increase and that should help to build the waves slightly over the next hour or two, but the pressure gradient is expected to weaken during the mid to late afternoon hours and that will support diminishing winds and waves. No changes to the hazard headlines. && .DISCUSSION... Issued at 320 AM EDT Sun Aug 11 2024 - Fair weather today through Monday Any isolated early morning light rain showers and sprinkles will end by mid morning as the upper level trough/vort max departs. It will be partly sunny today with pleasant high temps reaching the low to mid 70s as per latest ensemble guidance numbers. 00Z HREF guidance suggests sct-bkn cloud cover will be moving out by late afternoon with skies becoming mostly clear tonight. 925-850 mb temps continue to slowly moderate Monday. A sct-bkn fair wx cu deck will likely develop particularly near to east of US-131 along with some sct high cloud cover. It will be several degrees milder Monday with high temps reaching the upper 70s to lower 80s. - Dry through midweek; better support for late-week rain There now appears to be growing support in deterministic and ensemble guidance for some appreciable rainfall toward the end of the coming week into next weekend. A digging upper trough approaching from the nrn Plains helps to draw up Gulf moisture (PWATs >1.5") by Thursday night although decent spread exists regarding the amplitude/movement of the upper trough and the strength of the sfc reflection over the weekend. The number of EC/CMC ensemble members showing 24 hour QPF over 1" between Thursday night and Saturday has grown substantially and NBM pops have trended up during this period as well. Best support for the more substantial rain amounts looks to be in the Thursday night/Friday timeframe although GEFS not looking quite as convincing as EC/CMC. The slow moving trough and sfc system slowly drift through the area over the weekend which keeps shower and tstm chances going. However the extent and duration of continuing rain chances look to hinge on whether or not the upper low closes off overhead/nearby or if it is a more progressive system. Otherwise little change in thinking regarding the stretch of dry weather continuing through mid week with near normal temps (highs near 80) as surface ridging/dry air mass dominates. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1240 PM EDT Sun Aug 11 2024 No changes to the TAFs. Diurnal cu will largely dissipate toward sunset leaving FEW-SCT070. Gusty west winds will all diminish to less than 10 knots after sunset. && .MARINE... Issued at 320 AM EDT Sun Aug 11 2024 A beach hazards statement and sca remains in effect until late this afternoon as fairly brisk wnw winds will result in wave heights reaching around 3 to 5 feet. Winds and waves will finally subside tonight as the low moves further away and pressure gradient weakens. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until 5 PM EDT this afternoon for MIZ037- 043-050-056-064-071. MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LMZ844>849. && $$ UPDATE...MJS DISCUSSION...Meade/Laurens AVIATION...04 MARINE...Laurens