During summer and early fall in South Florida (I used the term “fall” loosely, summer lasts 7-8 months down here), we have a thunderstorm just about every day in the early afternoon. With it comes lightning, flooding, occasional hail, a number of fender-benders and other assorted mishaps.
Thunderstorms and Their Dangers
Although these are rarely life-threatening, I thought about how common they are down here and in so many other parts of the country. Yet, I have only written about hurricanes, tornadoes, wildfires, and earthquakes with no thought as to the much more frequently encountered thunderstorm. Thunderstorms can occur anywhere where cooler air collides with warm, moist air.
A storm is considered severe if certain events occur:
1)Wind reaches 58 miles per hour (93 kilometers per hour)
2)Hail reaches an inch (25 mm) in diameter
3)A tornado funnel cloud forms
4)2 or more inches of rain fall in an hour (Canada)
The risks of severe storms are several, including the following:
Lightning: Lightning occurs more than a billion times a year. About 25% of these will strike the ground. In a typical storm, lightning strikes happen 2-3 times per minute until the storm begins to dissipate. Weather conditions are so favorable in the tropics that 70% of lightning strikes occur there. Thunder is a sound wave that emanates from the lightning. The sound waves form along the length of the lightning’s path; if a lightning bolt was perfectly straight, it would be a single crack or boom. As lightning takes a jagged course to the ground, however, it causes a rumbling effect.
Sound travels about 350 yards per second, so you can estimate the distance between you and a lightning strike by counting the seconds between seeing the lightning and hearing the accompanying thunder. 5 seconds would be about a mile.
It is extremely rare to become a victim of a lightning strike. The majority survive the event, albeit often with some long-term nerve or mental damage. Staying away from metal fixtures in a home or car during a severe storm or away from tall objects, (for example, trees and utility poles) when outside are good strategies to avoid a lightning injuries. Also, wait for the storm to pass before showering; plumbing fixutres conduct electricity.
Hail: Once a thunderstorm produces hailstones, it becomes a “hailstorm”. Most common in mountainous areas, areas of Colorado, Wyoming, nearby states and parts of Canada comprise a “Hail Alley” just as areas of the Midwest have a “Tornado Alley”.
Hail often causes damage to vehicles, roofing, glass, and worst of all, crops and livestock. Aircraft may be damaged by airborne hail as small as a half-inch in diameter. Landing may be difficult due to hail on the ground.
To protect yourself, make sure you and your animals are inside when a major storm is likely. If you’re on the highway, get under an overpass or into a building’s parking garage as soon as possible.
FLOODING: Flash flooding is the process where a landscape is inundated as a result of large volumes of rain from a storm. For a discussion of this subject, see our article on Flood Safety:
TORNADOES: The formation of tornadoes in a storm is the cause of major destruction in many cases. We have driven through Joplin and Branson, Missouri, and can tell you that Mother Nature can be a harsh mistress. For our article on tornadoes, go here:
DOWNBURSTS: Downburst winds are often mistaken for tornadoes,due to the force of their winds. They are, however, actually quite different. In a tornado, the winds circle a central point inward and upward; in a downburst, winds travel downward and then outward from their landing point on the ground.
As in a tornado, crops, livestock, vehicles, and homes can be destroyed. Aircrafts taking off or landing are disrupted due to downburst, which are more difficult to identify that the classic funnel cloud.
Here are American Red Cross Guidelines for storm safety:
Don’t ignore thunder. Anyone close enough to hear thunder can be struck by lightning.
Avoid electrical appliances not attached to power surge protectors. Cordless telephones are safe to use during a thunderstorm.
Close all windows and doors; high winds can break glass.
Do not bathe or shower; plumbing conducts electricity.
If driving, safely exit the road, and park away from trees or utility poles. Remain in the vehicle and avoid touching metal. If you can find a building with a garage, drive inside.
Get inside a safe, sturdy building. If this is not possible, take cover in a low area and minimize contact with the ground.
Joe Alton, M.D., aka Dr. Bones, the Disaster Doctor