I was in the Stanley basin last week and I was surprised at the amount of snow. I expected it to be much more grim.
It is early. Your date is borderline. You won't know anything valuable for at least 6 weeks. You can cancel with no penalty if the road is closed. If MFS fails just head to main salmon pre-season.
On Banner Summit probably half of the SWE we expect comes after today.
NWCC Report Generator
Just plan for marsh creek plan B.
That being said if I held a June 3 MFS permit I would feels 80% good about it. If someone invited me on said permit I would feel 90% good about it.