Thursday, March 27, 2014

Thunderstorms & Lightning

Thunderstorms & Lightning

The following is from the Dakota County Emergency Management Team.

All thunderstorms are dangerous. Every thunderstorm produces lightning. While lightning fatalities have decreased over the past 30 years, lightning continues to be one of the top three storm-related killers in the United States. In 2010 there were 29 fatalities and 182 injuries from lightning. Although most lightning victims survive, people struck by lightning often report a variety of long-term, debilitating symptoms.
Other associated dangers of thunderstorms include tornadoes, strong winds, hail and flash flooding. Flash flooding is responsible for more fatalities – more than 140 annually – than any other thunderstorm-associated hazard. Dry thunderstorms that do not produce rain that reaches the ground are most prevalent in the western United States. Falling raindrops evaporate, but lightning can still reach the ground and can start wildfires.
They may occur singly, in clusters or in lines.
Some of the most severe occur when a single thunderstorm affects one location for an extended time.
Thunderstorms typically produce heavy rain for a brief period, anywhere from 30 minutes to an hour.
Warm, humid conditions are highly favorable for thunderstorm development.
About 10 percent of thunderstorms are classified as severe – one that produces hail at least an inch or larger in diameter, has winds of 58 miles per hour or higher or produces a tornado.
Lightning’s unpredictability increases the risk to individuals and property.
Lightning often strikes outside of heavy rain and may occur as far as 10 miles away from any rainfall.
“Heat lightning” is actually lightning from a thunderstorm too far away from thunder to be heard. However, the storm may be moving in your direction.
Most lightning deaths and injuries occur when people are caught outdoors in the summer months during the afternoon and evening.
Your chances of being struck by lightning are estimated to be 1 in 600,000 but could be reduced even further by following safety precautions.
Lightning strike victims carry no electrical charge and should be attended to immediately.

Why Worry About Thunderstorms? 

■ Causes an average of 55-60 fatalities and 400 injuries each year
■ Occurs with all thunderstorms
■ Costs more than $1 billion in insured losses each year
■ Cause an average of 60-65 fatalities and 1,500 injuries each year
■ Can produce wind speeds in excess of 200 mph                                                                       
■ Can be 1 mile wide and stay on the ground over 50 miles
Straight-line Winds...
■ Can exceed 125 mph
■ Can cause destruction equal to a tornado
■ Are extremely dangerous to aviation
Flash Floods and Floods...
■ Are the #1 cause of deaths associated with thunderstorms, more
than 90 fatalities each year
Can be larger than a softball (5 inches in diameter)
■ Causes more than $1 billion in crop and property damage
each year

One dangerous aspect of weather that sometimes is not taken as seriously as others is lightning. Summer is the peak season for one of the nation’s deadliest weather phenomena, but don’t be fooled, lightning strikes happen at all times of the year. In the United States, an average of 53 people are killed each year by lightning. In 2012, 28 people died due to lightning. In 2013, 23 people were struck and killed, while hundreds of others were permanently injured. Of the victims who were killed by lightning in 2013:
§  91% were outside
§  74% were male
§  52% were between the ages of 20 - 39         
§  30% were between the ages of 50 - 59
§  30% were in or near water
§  22% were near or under trees

Avoid getting caught in a dangerous situation! If you can hear thunder, you are close enough to be struck by lightning!

Move into a sturdy building or an automobile with a metal top. The frame of the building or of a metal car body will allow the charge to be conducted away from you.
§  Outdoor activities such as golfing and baseball can present a risk to those in attendance, as these take place on a fairway or ball field, both of which are wide open. Those attending rodeos or concerts in open arenas, sitting on metal bleachers or under a metal overhang, are also at risk.
§  Get out of boats and away from water, as water is an electrical conductor. On the open water, you may become the tallest object and a prime target.
§  When indoors, avoid using any corded and electrical appliances. Also stay away from pools, tubs, showers, or any other plumbing. Electricity can travel through wiring and plumbing, posing a risk to those in contact.
§  If someone is struck by lightning, get medical help immediately. With proper treatment, including CPR if necessary, most lightning victims survive.


Did you know… Thunderstorms do not have to be large in size or even severe to create potentially fatal lightning strikes!

As a thunderstorm grows, areas of rising and descending air cause a separation of positively and negatively charged particles within the storm. At the same time, oppositely charged particles are gathering on the ground below. The attraction between the particles in the cloud and at the ground quickly grows, and once the force is strong enough to overcome the air’s resistance, lightning occurs.

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