563 FXUS63 KGRR 120713 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 313 AM EDT Tue May 12 2026 .KEY MESSAGES... - Showers today; afternoon/evening thunder possible - Frost possible north Wednesday night - Warmer with showers/storms possible late weekend and next week && .DISCUSSION... Issued at 312 AM EDT Tue May 12 2026 - Showers today; afternoon/evening thunder possible An approaching clipper will push isolated showers through the cwa this morning. However, during the afternoon, coverage of the showers will increase as the low gets closer. Although instability isn`t overwhelming, mid level lapse rages increase to 6.5-7c/km this afternoon that may result in a few storms 21z-03z. Lift will also be aided by the arrival of the accompanying upper level short wave. Expect the strongest storms to remain west and southwest of the cwa. - Frost possible north Wednesday night Colder air will flow into the region once again behind the clipper. Highs Wednesday will be in the upper 40s north to mid 50s south and lows Wednesday night will fall into the mid 30s along the northern row of counties. Thus, another frost advisory may be needed Wednesday night. - Warmer with showers/storms possible late weekend and next week Late in the weekend, we develop a broad southwest flow as ridging takes hold over the northeast US. This will send a plethora of short waves moving up the ridge toward the Great Lakes. As moistureand temperatures increase, the result will be an increase in convective development. NCAR medium range AI ensembles point toward Sunday and Monday as timeframes when convection could be stronger. It`s during this time that a developing low over the Plains begins to lift north and a warm front moves into the cwa followed by the trailing cold front. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 312 AM EDT Tue May 12 2026 Skies are clear across the region, but high clouds and some precipitation are moving toward Lower MI from Wisconsin. A clipper system will move across the state today and bring some lower...but still VFR...cigs to the terminals. Additionally, models are showing some potential for a few thunderstorms after 21z through mid evening. Finally, a LLJ is progd to move over the region later this evening, which will create some LLWS. && .MARINE... Issued at 312 AM EDT Tue May 12 2026 No changes to the small craft advisory. Winds and waves will pick up in speed and height as the pressure gradient tightens in response to a clipper moving across the state. Highest waves will be north of Holland this afternoon. After a brief lull, the winds will shift to the northwest tomorrow and waves will build southward during the afternoon. The small craft advisory may have to be extended in time Wednesday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Freeze Warning until 8 AM EDT this morning for MIZ037>040-045- 046. Frost Advisory until 8 AM EDT this morning for MIZ043-044- 050>052-056>059-064>067-071>074. MARINE...Small Craft Advisory from 8 AM this morning to 8 AM EDT Wednesday for LMZ844>849. && $$ DISCUSSION...04 AVIATION...04 MARINE...04

NWS GRR Office Area Forecast Discussion