408 FXUS63 KGRR 271059 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 659 AM EDT Wed May 27 2026 .KEY MESSAGES... - Thunderstorm Potential this Afternoon/Evening - Quiet Weather the rest of the Week && .DISCUSSION... Issued at 217 AM EDT Wed May 27 2026 - Thunderstorm Potential this Afternoon/Evening Hi res models are picking up on the potential for convection along the southward moving cold front this afternoon and evening. The potential has been indicated for a few days by model soundings showing 500 to 1000 J/kg of CAPE across the southeast forecast area. Limiting factor appears to be a lack of deep moisture as seen in forecast soundings, but this also indicates a strong downdraft potential with a pronounced dry wedge beneath the LCL. For POPs this afternoon, the Hires ARW forecast POPs were smoothed out and the timing, which is a bit later than the NBM, was followed. Expect the showers and storms to be weakening with the loss of insolation as they depart the SE zones by around 10 pm. Isolated severe winds and hail are possible with any sustained updrafts. - Quiet Weather the rest of the Week High pressure building in on Thursday with generally dry northwest flow regime into the weekend as the Omega block across North America finds the Great Lakes in between the upper high over central Canada and a trough across eastern Canada into the NE CONUS. Another cold front moves through from the north on Saturday but limited moisture suggests chance for any rain will be less than 20 percent with that fropa. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 658 AM EDT Wed May 27 2026 VFR conditions will prevail through Wednesday evening except for isolated MVFR and even a low chance of brief IFR in thunderstorms late this afternoon into early evening. Strong gusty surface winds greater than 30 knots and hail are possible with these storms but coverage should be limited and most likely between LAN and JXN around 22Z to 03Z. && .MARINE... Issued at 217 AM EDT Wed May 27 2026 Still looks like a SCA will be needed Wednesday night into Thursday evening with a tight surface pressure gradient as a high builds in producing north winds to 25 knots. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ostuno AVIATION...Ostuno MARINE...Ostuno

NWS GRR Office Area Forecast Discussion