LIGHTNING INJURIES - Medicine for Mountaineering and Other Wilderness Activities - page 441

AREAS WITH GREATEST LIGHTNING RISK
Thunderstorms can occur almost anywhere, but individuals enjoying outdoor activities
should be aware of the geographic, seasonal, and diurnal tendencies. Those who live in
the Rocky Mountains clearly understand that during any summer afternoon, the chance of
thunderstorm development with associated lightning risk exists. In the United States, the
National Lightning Detection Network (NLDN) measures lightning strike densities, which
are greatest over central Florida (more than ten strikes/km 2 ). The Southeast and Midwest
have the next greatest lightning strike frequency. The risk starts primarily in May, peaks in
July,andfallsabruptlyinSeptember.ThelowestfrequencyisinJanuary.Thepeakdaytime
hours are afternoons and evenings. With seasonal variations, during certain weeks of the
summer the front range of the Rockies equals the flash density of central Florida.
Thenumberoflightningcasualtiesisdependentuponmanyelements,suchasthesever-
ity of the thunderstorm and lightning strike density, population density, popularity of out-
door activities, awareness of lightning risk, and safety precautions utilized. One major
factor for those who enjoy the mountains is higher elevation. Sunday has the most casu-
alties; Saturday is next—the days more people are outdoors. The most common hours are
July between noon and 6:00 PM local time. Males are struck more often than females be-
cause more men take part in outdoor activities.
Even though the highest numbers of lightning deaths are in Florida, Texas, Michigan,
Pennsylvania, North Carolina, and New York, the highest per capita states are Wyoming,
New Mexico, Florida, Arkansas, and Colorado ( Table 29-2 ). The Rocky Mountain States
have a low population and lightning flash density but have a number of people at high risk
because they are outside at times of high strike numbers.

More Facts About Lightning
◆ From National Center for Health Statistics data: From 1980 to 1995, 85 percent of
lightning fatalities were men, and 68 percent were fifteento forty-year-olds. The annu-
al death rate from lightning was highest among persons fifteen to nineteen years old.

Table 29-2 Lightning Casualty Demographics

• 92 percent of casualties occur between May and September, peak in July
• 73 percent of casualties occurred in the afternoon from noon to 6:00 PM
• Highest numbers of deaths occur in Florida and Texas (National Center for Health
Statistics [NCHS])
From population normalized data, Wyoming has the highest lightning casualty rate
(0.196/100,000inhabitants),followedbyNewMexico,Florida,Arkansas,andColor-
ado.