FXUS63 KGRR 262256

AFDGRR



Area Forecast Discussion

National Weather Service Grand Rapids MI

656 PM EDT Thu Jun 26 2025



.KEY MESSAGES...



- Highest Chances for Rain will be Friday and Monday



&&



.DISCUSSION...

Issued at 217 PM EDT Thu Jun 26 2025



Diurnally-enhanced convection along a warm front will persist

into this evening then should diminish overnight. More storms will

fire up on Friday in the warm sector and ahead/along a cold front

as a sfc low tracks across northern Lower Michigan. The front

clears southeast zones late Friday night with a brief period of

fair weather and lower dew points into Sunday morning.



By Sunday afternoon, return flow is already setting up as a

shortwave trough embedded in zonal flow moves from the Plains 

into the Great Lakes. Dew points surge back into the 70s by Monday

with a cold front arriving by afternoon. Instability is 

sufficient for enhanced thunderstorm coverage but deep layer 

shear is only around 20 to 25 knots, so storms may be more of the 

pulse variety.



Dew points behind the front fall into the 50s to lower 60s for

Tuesday through Thursday offering a break from the recent

oppressive humidity. Long range indications are for the 

possibility of some storminess on the 4th, but confidence is low 

in the details.



&&



.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...

Issued at 652 PM EDT Thu Jun 26 2025



Radar shows showers and thunderstorms continuing to weaken and

dissipate across the region this evening. It's looking more likely

that the convection west of the lake will dissipate prior to

crossing the lake around midnight and won't be a factor in the

TAFs. 



Showers/storms will likely develop again Friday afternoon and will

mostly affect BTL/LAN/JXN after 19z. VFR expected through the

period.



&&



.MARINE...

Issued at 139 PM EDT Thu Jun 26 2025



Waves will build to around 2 feet north of Holland Friday

afternoon. Otherwise waves will generally be less than 2 feet for

the next couple of days.



Thunderstorms remain a possibility this afternoon and again Friday

afternoon.



&&



.GRR WATCHES/WARNINGS/ADVISORIES...

MI...None.

MARINE...None.



&&



$$



DISCUSSION...Ostuno/RAH/Thomas

AVIATION...04

MARINE...RAH

