076 FXUS63 KGRR 042356 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 756 PM EDT Fri Jul 4 2025 .KEY MESSAGES... - Small chance of a shower/storm through Saturday; Otherwise Hot - Shower and storm chances increase Saturday night into Sunday night - Dry Monday and Tuesday; Rain Chances Wednesday-Thursday && .DISCUSSION... Issued at 243 PM EDT Fri Jul 4 2025 - Small chance of a shower/storm through Saturday; Otherwise Hot The SW portion of the area had to contend with some showers and storms that lingered longer than expected this morning. Those have since fizzled out quickly as the low level jet and moisture return have weakened considerably over the last few hours. We will be left with only small 20-30% chcs of a shower or storm this afternoon east of U.S.-131. The atmosphere is still quite unstable with the heat and moisture still around, and upper ridge building over the area. Forecast soundings show the mid levels warming a bit with the upper ridge building overhead later this afternoon and evening. This will essentially cap the atmosphere, and reduce the small chances of rain even more. This will be the case through Saturday. The clouds have limited the heating a bit today for the southern half of the area. We will see clouds scatter out a bit, and allow for temps to warm to 90F today. 850 mb temps warming to around 20C with the heat dome overhead will allow temps to warm into the lower 90s for Saturday. Dew points are not going to be too oppressive in the low to mid 60s F. This should limit the potential for any type of heat headlines being needed with heat indices expected to stay below 100F. - Shower and storm chances increase Saturday night into Sunday night The second half of Saturday night will see the cold front to our NW drop in late. We will see shower/storm chances arrive over the NW corner of the forecast area after midnight, and then spread SE through Sunday morning. The timing of the front and rainfall being focused on late Saturday night and Sunday morning for a majority of the forecast area will limit any severe potential a bit. The lack of strong instability without any help from a diurnal boost will also keep things mostly tame. In fact it may limit rainfall for the Central and Northern portions of the forecast area. Southern areas will see the best instability build with some heating taking place before the rain/front will move in. Sfc based LI`s are forecast to drop to around -4 to -5C and MU CAPE increasing to over 1,000 J/kg. Even with the best instability, deep layer shear values are wimpy, with only 15 to 20 knots of 0-6km shear. This situation looks like it will mainly be a beneficial rain, with little to no chance of severe weather. The front will sink south of the area Sunday night, taking the rainfall with it. - Dry Monday and Tuesday; Rain Chances Wednesday-Thursday Once we see the front sink south of the area, dry and cooler weather should return to the area for Monday. The upper heights drop a bit as the weekend upper ridge gets flattened well. Sfc ridging will then dominate over the area Monday through Tuesday. A flow from the north and east will bring in slightly cooler temperatures, and much drier air. This will hold over the area until at least Tuesday evening as the sfc ridge slips east of the area. Rain chances then look to return to the area for Wednesday and Thursday, with cooler temperatures holding in over the area. The upper jet will be dropping in over the Upper Midwest, and allowing a short wave trough to move over the area. This system will not have much moisture to work with as we do not see a moist flow set up from the Gulf ahead of the sfc front. The short wave will mostly act with diurnal instability to fire a few showers and storms Wed and Thu afternoons. There is some uncertainty as to how quick this system moves out toward the end of next week. We feel it is more likely to move out by next Friday, but can not rule out it sticking around a little longer. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 745 PM EDT Fri Jul 4 2025 A lone shower north of MKG continues to move to the northeast. With fading daylight, expect any convection to end. Overall VFR will dominate the weather through the period. Winds will slowly weaken as the inversion builds. Light southwesterly flow will persist through most of the evening. While it shouldn`t directly affect TAF sites, there could be some haze that could reduce vsbys between 03Z to 06Z. Winds will again become gusty tomorrow after 15Z. && .MARINE... Issued at 243 PM EDT Fri Jul 4 2025 We will be issuing Small Craft Advisories and Beach Hazards Statements for the weekend with this afternoon`s forecast cycle. No problems with winds and waves through Saturday morning with a lighter pressure gradient in place. Winds will then increase for the northern half of the marine zones beginning Saturday afternoon. This takes place as a result of the cold front pressing down closer to the area. The area of concern for Saturday will be north of Muskegon with the increasing flow from the SW. The winds will then spread down a bit further Saturday night to around Holland. Winds will then switch to become from the NW on Sunday as the cold front moves through. Areas south of Holland do not look to be as strong as the north at this time. Once the wind and waves subside on Sunday afternoon/evening, winds should stay on the lighter side for a good period of next week. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement from Saturday afternoon through Sunday evening for MIZ037-043-050. Air Quality Alert until midnight EDT Saturday night for MIZ050- 056-057-064-071. Beach Hazards Statement from Saturday evening through Sunday evening for MIZ056. MARINE...Small Craft Advisory from 8 PM Saturday to 8 PM EDT Sunday for LMZ846. Small Craft Advisory from noon Saturday to 8 PM EDT Sunday for LMZ847>849. && $$ DISCUSSION...NJJ AVIATION...Ceru MARINE...NJJ

NWS GRR Office Area Forecast Discussion