DETROIT (AP) -- Heavy rains that pounded parts of Michigan for a second day Saturday disrupted Detroit-area air travel while leaving thousands without electricity.

Detroit Metropolitan Airport grounded many flights Saturday morning but was operating normally about 90 minutes later. About 90 Northwest Airlines flights had been cancelled after storms Friday.

''It doesn't look that bad,'' airport spokesman Mike Conway said Saturday. ''Everything's still moving.''

About 7,500 Detroit Edison customers were without power, said utility spokesman Lew Layton. Most residents will have their power restored by Saturday night, he said.

A few hundred Consumers Energy customers who also lost power will have their service restored by midnight Saturday, a spokesman said.

The National Weather Service said an average of 2.3 inches of rain fell by Saturday afternoon. Flash flood watches were posted for much of southeast Michigan, which could get as much as 5 inches of rain.

''The main concern is for the motorists who are out on the streets, but people with property should take stock of their surroundings,'' said Darin Figurskey, a meteorologist in Oakland County.

The storms Saturday and Friday caused as much as 8 inches of water to pool on stretches of Interstate 75 near Flint, reducing the freeway to just one usable lane in both directions.