May 12, 2000. A supercell thunderstorm moves across Manitowoc County with 100 mile per hour winds and three inch diameter hail. Winds cause $100 million in damage in St. Nazianz and neighboring communities, making it the costliest storm in the U.S. that year.
Thunderstorms affect relatively small areas compared with winter storms. A typical thunderstorm is 15 miles in diameter and, on average, lasts 30 minutes. Despite their small size, all thunderstorms are dangerous. Every thunderstorm produces lightning (thus the thunder), which on average kills 93 people and injures 300 every year. Heavy rain can lead to flash flooding, which is even deadlier than lightning with nearly 140 fatalities each year.
Thunderstorms can produce straight-line winds exceeding 100 miles an hour. One type of wind, the downburst, can cause damage equivalent to a strong tornado and is extremely dangerous to aviation. Thunderstorms can also spawn tornadoes with winds exceeding 200 miles an hour.
Take the time now to understand these dangers and learn basic safety rules!
Watches and Warnings
Severe Thunderstorm Watch Conditions are favorable for severe weather. When a Severe Thunderstorm Watch is issued for your area, tune to WBAY-TV for updated weather warnings.
Severe Thunderstorm Warning Severe weather is imminent. Winds of 58 miles an hour or greater, hail 3/4" in diameter, or tornadoes have already been indicated by radar or reported by trained observers. Take action immediately.
Also listen for Tornado Watches and Warnings, and Flash Flood Watches and Warnings.
Metal pipes and telephone lines can act as conduits for electricity from a nearby lightning strike. The average lightning flash has enough power to light a 100-watt bulb for three months.
Unplug appliances not necessary for obtaining weather information. Turn off air conditioners. Avoid using the telephone or electrical appliances, and use phones only in an emergency.
Don't use the shower or bathtub.
Stay away from windows, and appliances or anything metal.
Get to higher ground if flash flooding is possible (see Flood Safety)
Lightning kills more people each year than tornadoes, but the leading cause of deaths in thunderstorms is not lightning, it's flash flooding.
If you can hear thunder, then you are close enough to the storm to be struck by lightning. Go to safe shelter immediately.
Get out of boats and away from water (see information below if you are caught in the open water during a storm).
Move to a sturdy building. Do not take shelter in small sheds, under isolated trees, or in soft-top or convertible automobiles.
If lightning is occurring and a sturdy shelter is not available, get inside a hard-top vehicle and keep the windows up.
Get away from open areas like golf courses, baseball fields, and playgrounds.
Find a low spot away from trees, fences, and poles, but make sure your spot is not subject to flash flooding.
If you are in the woods, take shelter under shorter trees.
If you feel your skin tingle or hair stand on end, squat low to the ground on the balls of your feet, place your hands on your knees with your head between them (think of the airplane "crash position" while squatting on your tip-toes). Make yourself the smallest target possible and minimize your contact with the ground.
On the Water
If severe weather is possible, stay in touch with the latest storm information. Winds can kick up quickly and seas can build rapidly, so stay on top of changing conditions.
Small Craft Advisories are designed to alert mariners more than two hours in advance of hazardous weather and sea conditions. Threatening conditions are usually sustained winds of 18 knots (21 mph) or hazardous waves within five miles of shore.
Everyone should be wearing a life preserver, despite weather conditions. Make sure your boat has a bailer onboard.
Head for dock. If you are caught in the storm, face the bow into the wave to prevent capsizing.
If you capsize, stay with the boat. You'll be easier to find.
Facts and Fictions
Fiction: If it's not raining, there's no danger from lightning. Fact: Lightning often strikes outside of heavy rain, and can occur as far as 10 miles away from any rainfall.
Fiction: The rubber soles of your shoes or rubber tires on a car will insulate you from lightning. Fact: Rubber soles or tires provide NO protection from lightning-- which can heat the air hotter than the surface of the sun. The steel frame of a hard-topped vehicle provides some protection if you are not touching anything metal. You are much safer inside a vehicle than outside.
Fiction: People struck by lightning carry an electrical charge and should not be touched. Fact: Lightning-strike victims carry no electrical charge and should be attended to immediately for first aid and CPR.
Fiction: Heat lightning on hot summer days poses no threat. Fact: What is called "heat lightning" is lightning from a storm too far away to hear the thunder. Remember, the storm may be moving in your direction and lightning bolts can strike 10 miles from the rain.