Iowa-made movies like “Twister” have increased the popularity of chasing tornadoes in recent years. Experts say it’s extremely dangerous and recommend against it. National Weather Service meteorologist Jeff Wallenfang says people should take shelter from severe storms instead of taking off in a vehicle and trying to see a funnel up close. He says some storm chasers don’t know what they’re doing and put themselves and others in danger.Wallenfang says advancements in Doppler radar have helped in issuing tornado warnings, but forecasters also depend on trained spotters and law enforcement officers for input.Wallenfang, who works at the Weather Service office in Johnston, says when a tornado warning is issued, you should take shelter immediately. He says warnings can sometimes be issued base on radar.A statewide tornado drill will be held at ten o’clock this morning, starting with a test tornado watch. A test tornado warning will follow. Government agencies, private companies, schools, and the general public are urged to test tornado emergency procedures during the drill.