Basics of Tornadoes
When it comes to tornadoes, there's no such thing as a "tornado season." Tornadoes can strike anywhere, anytime and you need to be ready.
Environmental clues that indicate an approaching tornado include a dark, often greenish sky, large hail and a loud roar similar to a freight train. The general rule for tornado safety is "go low and stay low," meaning go to the lowest level of the structure away from windows and crouch in a low position with your head covered.
Know the Signs
• Strong, persistent rotation in the base of a cloud.
• Whirling dust or debris on the ground under a cloud base - tornadoes sometimes have no visible funnel.
• Hail or heavy rain followed by dead calm or a fast, intense wind shift. Many tornadoes, especially in Virginia, are wrapped in heavy precipitation and can't be seen.
• Loud, continuous roar or rumble, which doesn't fade in a few seconds like thunder.
• If it's night, look for small, bright, blue-green to white flashes at ground level (as opposed to silvery lightning up in the clouds). These lights are power lines being snapped by very strong wind, maybe a tornado.
• Persistent lowering of the cloud base.