338 FXUS63 KGRR 260617 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 217 AM EDT Sun Apr 26 2026 .KEY MESSAGES... - Dry Until Chances for Rain and Thunderstorms Monday Night - Mainly Dry and Cooler for the Remainder of Next Week && .DISCUSSION... Issued at 245 PM EDT Sat Apr 25 2026 - Dry Until Chances for Rain and Thunderstorms Monday Night Upper level ridging and high pressure will remain in place through the weekend resulting in dry conditions. Southwest flow moves in Monday ahead of the shortwave trough. Upper level divergence, positive vorticity advection, and the low level jet line up for late Monday afternoon into Monday night. There will be plenty of shear in place with the 50 knot low level jet with winds up to 70 knots in the mid levels. The question on our severe potential will largely be up to how much instability is available. NBM mean SBCAPE has instability ranging from a few hundred to a couple hundred J/kg toward US-10 to near 1000 J/kg toward the I-94 corridor. If these instability values remain the same or increase, the SPC outlook would likely trend upward as we get closer. After the initial round of thunderstorms Monday night, some lingering rain showers are possible into Tuesday morning. - Mainly Dry and Cooler for the Remainder of Next Week Overall we`ll remain under the upper level trough with the potential for a couple shortwave troughs to move through. These troughs could bring some chances (20 percent) for light showers, but moisture is limited with precipitable water values remaining low. Highs through the week are expected to be in the 50s with lows in the 30s bringing the risk for a widespread frost. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 217 AM EDT Sun Apr 26 2026 Main focus of the 06Z to 06Z TAFs are the low clouds marching westward across the Lower Peninsula. The current thinking is that these clouds will envelope all of the TAF sites by roughly 08Z. Ceiling heights are around 1,000. We expect the ceilings to remain at or just above 1,000 feet through daybreak. A slow lifting of the ceilings will occur after 12Z. The low clouds should scatter out through the course of the morning hours with VFR conditions breaking out again at all TAF sites between 14Z and 16Z. VFR weather will then prevail for the remainder of the TAF forecast period with high clouds spilling in from the west around 00Z. Winds will remain easterly through the next 24 hours at 5 to 15 knots. && .MARINE... Issued at 245 PM EDT Sat Apr 25 2026 Winds are overachieving this afternoon and with an expected trend upward, expect gusts to be in the 25 to 30 knot range until this evening. With this change have issued a Small Craft Advisory until 8PM. Winds are expected to weaken and turn more easterly tonight into Sunday with low wave heights. Monday winds turn to the southwest with a chance for thunderstorms to move in during the late afternoon and evening. Small craft advisory conditions are likely for Monday into Tuesday. Winds should remain below gales due to the cold waters, however storms could be strong to severe and mix down stronger winds from aloft. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...RAH AVIATION...Duke/Thomas MARINE...RAH

NWS GRR Office Area Forecast Discussion