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Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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560 FXUS63 KGRR 251936 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 336 PM EDT Tue Jun 25 2024 .KEY MESSAGES... - Patchy fog with a chance of showers Wednesday morning/afternoon - High Pressure tracks through Thursday into early Friday - Thunderstorm chances increase Friday afternoon into Saturday && .DISCUSSION... Issued at 301 PM EDT Tue Jun 25 2024 - Patchy fog with a chance of showers Wednesday morning/afternoon Strong westerly flow will continue through the rest of the day keeping wind gusts upwards of 30 mph. The strong flow will keep the area mixed before winds finally start to subside mid to late evening. Much of the area along and south of I 96 received an inch or more with areas along the lakeshore receiving several inches of rain. With drying in the mid levels, calm winds at the sfc, a strengthening sfc inversion and trapped low level moisture, patchy fog is expected along and south of I 96, especially along the lakeshore. Patchy dense fog in low lying regions is possible. Any fog will lift/dissipate by late morning. A weak trough will swing through tomorrow, late morning into the afternoon. There is a chance for storms with this system. This trough will bring with it a low level jet, though it is only around 30kts. MEAN CAPE values are below 1000 J/kg. Daytime highs are expected to only get into the low 80s. So while there is enough instability, shear and dynamics for storm formation, there shouldn`t be enough for severe. Skies should clear in the wake of the exiting trough mid to late afternoon tomorrow. - High Pressure tracks through Thursday into early Friday Models are in decent agreement in showing a larger Canadian high pressure system tracking east southeast through Lower Michigan during this timeframe. Stronger subsidence arrives as this system moves in Thursday leading to mainly clear skies. Warm advection the backside of the departing wave will support an increase the mid to upper level clouds especially as the ridge axis will be east of the area. We will feature slightly below normal temperatures for this period. - Thunderstorm chances increase Friday afternoon into Saturday An impressive surge of moisture is shown to arrive ahead of the next storm system Friday afternoon/evening. PWAT`s are shown to climb up to around 2 inches. This is well above normal. The upper level jet strengthens as a trough builds in from the west. This trough axis pivots east of the area by 18z Saturday. The instability axis shifts east of the area by 18z Saturday. As a result the bulk of the thunderstorm activity should be prior to 18z Saturday. As a result, while we will feature some shower/storm activity Saturday, we will feature falling POPs, especially in the afternoon. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 138 PM EDT Tue Jun 25 2024 Gusty winds over 25 knots will continue for a few hours through mid afternoon but the winds will settle down later this afternoon as the mixing height decreases. An isolated shower/storm is possible this afternoon but overall the coverage is not expected to warrant adding them to the TAF forecast at this time. MVFR and possible IFR fog is now forecasted for later tonight. The recent rain will as some moisture to the low levels tonight which will elevated the fog risk. We are monitoring the storm risk for the southern TAF sites of KAZO, KBTL and KJXN for Wednesday morning. The atmosphere is forecast to destabilize there by several models but not all are in agreement on this scenario so we will hold off on adding them to the forecast at this time. && .MARINE... Issued at 330 PM EDT Tue Jun 25 2024 Strong winds will continue in the wake of the exiting system and will keep winds and waves dangerous to small craft and swimmers into this evening. Rapidly changing lake fluctuations will also create rip currents that will be dangerous to swimmers. Expect patchy fog early Wednesday morning which will reduce visibilities into mid morning. There will be a chance for showers and perhaps an isolated thunderstorm late Wednesday morning/early afternoon. Another small craft advsy/ beach hazards statement may be needed due to strong winds in the wake of an exiting system late Wednesday into Thursday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until 8 PM EDT this evening for MIZ037- 043-050-056-064-071. MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ844>849. && $$ DISCUSSION...MJS/Ceru AVIATION...MJS MARINE...Ceru