Madison dive teams are searching the bottom of Lake Mendota for a sailboat that sank.

Seven people were on board the 20-foot sailboat when it went under Memorial Day. It seems a sudden change in the weather played a role.

"The winds picked up very fast, the temperature dropped very quickly and it got rough out," said Jeff Nelson with the Dane Co. Sheriff's Dept.

"We call them popcorn storms because they literally almost pop up overhead on those warm sunny days," said Chris Kleppe with the UW Lifesaving station. "When you get those kind of conditions, the boaters need to get off quickly, and sometimes they may not have enough time to do that."

Kleppe and Nelson are still putting the pieces together about what happened Monday afternoon. They know seven boaters were stranded in the middle of the lake after they say their boat sank. Luckily another boat nearby heard their cries for help, and brought the group back to shore.

Safety officials say checking the forecast ahead of time and following lake patrol's warnings to come in while on the water can help prevent this kind of situation.

"I mean, there's a hundred websites on the computer before you go out," Nelson said. "And just check to see what the weather is doing. Also, there are so many smart apps on smart phones that you could dial up anytime at the end of the day."

"I would also recommend, now they also have these small hand-held radios, they're VHF, they're Marine radios, you can carry these on board," Kleppe. "This one is waterproof. So if it goes in the water, I can still use it. We monitor the radio frequencies in the tower here, so we know if somebody's calling on one of these. You go out on the water, you continue to call and ask for help, especially if your boat disappears."