Bert Jackson and his brother Cliff (left) had an electrifying experience on Muskegon Lake.

Bert Jackson knew “something different was going on” during a bass tournament on Muskegon Lake when the fishing lure that he cast hit the water -- but his line didn't.

Instead of falling on top of the water like all his other casts, the fishing line hummed and levitated in thin air, taking a curved shape that pointed directly up to storm clouds that began rolling over the lake.

When the same thing happened to his brother Clift, Jackson knew it was time to move their 18 ½-foot fiberglass bass boat for cover or risk losing much more than just the tournament.

“We knew there was a lot of static electricity in the air, but the storm seemed far enough away over Lake Michigan where we didn’t feel like we were threatened by lightning,” Jackson recalled about the incident about 15 years ago near Muskegon, Michigan. “We could hear thunder in the distance, but we didn’t see the flashes.”

The Jacksons navigated behind a retaining wall in a cove just in time to resume fishing and win the tournament before a “hellacious storm” came through with 4-foot waves and 65-mile-an-hour winds. “The fish were biting hard when we took cover,” Jackson said with a laugh. “We were just lucky, I guess.”

In more ways than one, according to experts at the National Weather Service (NWA). Most people who are killed by lightning strikes are participating in leisure activities, and fishing – not golf – topped the list of lethal recreations during thunderstorms in the service’s study of lighting deaths nationally from 2006 to 2012.

NWA Lighting Safety Specialist John Jensenius said people involved in fishing, camping and boating often wait too long when a storm is approaching and miscalculate how much time it will take them to reach a safe place. “More than 300 people are struck by lightning each year in the United States, and unfortunately about 30 of those incidents are fatal,” he said. “What we way is: When thunder roars, go indoors!”

Jensenius warns that if people can hear thunder, they are already in danger of being struck by lightning, which can travel as far as 10 miles away. A building with four walls and a roof or a car provide safety during a thunderstorm, but a hut, cabana, tent, or other rain shelter will not protect a person from being struck by lightning, the service said.

Common indicators for fishermen and boaters that static charges are reaching dangerous levels include brush discharges called St. Elmo’s Fire from points on a boat, strong static on AM radios and electric shocks from fishing reels and metal equipment.

Since sound travels a mile in about five seconds and light travels almost instantaneously, observers can estimate the distance of a lightning strike from their location by counting the seconds it takes from the time they view a lightning flash to the time they hear the thunder, then divide by five.