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Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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932 FXUS63 KGRR 071724 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 124 PM EDT Sun Jul 7 2024 .KEY MESSAGES... - Dry Sunday With Patchy Fog This Morning - Shower/Storm Chances Return Sunday Night - Convergent, moist flow through the first half of the week - Remnants of Beryl and an increase of warmth mid to late week && .UPDATE... Issued at 1154 AM EDT Sun Jul 7 2024 High pressure remains situated across Southwest Lower Michigan at midday. Winds are largely light and variable although south winds have developed at both Ludington and Big Rapids as the ridge starts to slip off to the east. Moisture return has already begun and is shown by the cumulus field that has rapidly developed in the southwest corner of the state near Benton Harbor and South Haven. Dew points are higher in that area. We expect cumulus clouds to fill in a bit across the forecast area as moisture gradually works back in. We expect the precipitation that has developed in Wisconsin and Illinois to remain west of our area this afternoon. Instability remains minimal through the afternoon over Southwest Lower Michigan per the HREF. The HREF also shows reflectivity moving out over the lake and dissipating as it does. Highs should mainly be in the 80s this afternoon. && .DISCUSSION... Issued at 347 AM EDT Sun Jul 7 2024 - Dry Sunday With Patchy Fog This Morning Nighttime microphysics imagery shows areas of fog and stratus have developed mainly north of I96 with other pockets on the Lake Michigan shoreline. Additional development will be focused on the region north of I96 and near/west of US131. Isolated pockets of dense fog cannot be ruled out. This fog will dissipate by mid- morning as solar heating ramps up. Dry weather is expected today as surface and mid-level ridging slide across the area. Expect beautiful weather in the form of partly to mostly sunny skies with highs in the low 80s. - Shower/Storm Chances Return Sunday Night Low to moderate (20-40 percent) PoPs return to the forecast Sunday night as warm air advection triggers the chance for showers mainly north of a Holland to Mount Pleasant line. With HREF MUCAPE < 500 J/kg, thunder coverage will be isolated at worst. Highest PoPs will be up near Ludington where low-level isentropic ascent is best. Troughing slowly advances into the upper Great Lakes Monday, with weak impulses ahead of this trough, combined with diurnal enhancement from warm July sunshine, reinvigorating a chance (20-40 percent) of showers and storms Monday. The highest PoPs will be north of I96 where the best shortwave forcing tracks. Given a general MLCAPE <1000 J/kg and deep layer shear < 30 knots, thunderstorms should be garden variety storms. Highs will range from near 80 across the NW CWA where morning showers and cloud cover will be thickest to the upper 80s across the southern CWA where sunshine lasts longer. - Convergent, moist flow through the first half of the week The pattern for the upcoming week will be dominated by a building high pressure system over the intermountain west and the corresponding deep trough moving through the central CONUS that will bring convergent moist flow over the midwest this week. The upper level 500mb trough will become a conveyor belt for moisture. Through this timeframe there is a lack of organized convection, however, the warm air advection along with the streaming of gulf moisture should couple with the daytime July temperatures to create an environment for cloudy skies and daytime showers and afternoon storms. Have scattered POPs through this timeframe. Latest WPC QPF that includes Tuesday into Wednesday has around an inch to an inch an a half along the I 94 corridor. - Remnants of Beryl and an increase of warmth mid to late week The big story mid to late week is the track of Tropical Storm Beryl and its affects on the region as it becomes extra tropical. The previously mentioned trough will be the main steering mechanism for Tropical storm Beryl as it moves through the central United States. The latest National Hurricane Center track has Beryl barreling through the Mississippi and Ohio river valleys mid to late this upcoming week with the cone of uncertainty covering most of Michigan`s lower peninsula by 7 PM Thursday. The biggest concern will be heavy rain showers due to the Gulf moisture. The latest mid to long range models, including the various ensembles tracks some showers from the remnants of Beryl Wednesday and Thursday. There remains some uncertainty on the track and timing especially when it comes to where the low will move through. Much of the ensembles still has the low moving through Ohio through some operational runs bring much of the moisture over southern Michigan. Due to this have increased POPS through this timeframe. Temperatures this week will meander around the upper 70s through the early part of the week ending in the upper 80s into next weekend which is just above normal for July. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 119 PM EDT Sun Jul 7 2024 Scattered to broken diurnal cu has developed across the region but will dissipate as sunset nears. High clouds from convection to the west will float across the region overnight. There may be some shallow fog that develops as well due to recent spotty rains. Models indicate more storms will develop over Iowa tonight and move northeast and potentially clip MKG/GRR after 09z. We added a VCSH comment for that possibility. && .MARINE... Issued at 347 AM EDT Sun Jul 7 2024 Patchy fog is possible across the nearshore waters tonight thanks to low-level moisture with satellite suggesting some has developed near Holland/South Haven. High pressure keeps southwesterly winds at or below 15 knots tomorrow and tomorrow night, and by extension keeps waves below small craft criteria. Benign marine conditions continue through at least Tuesday as no major gradient winds are expected to develop. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...Duke DISCUSSION...Ceru/Thomas AVIATION...04 MARINE...Thomas