Do you know your weather facts?
Here are some weather facts from the National Weather Service that all Texans should be familiar with:
- Severe Thunderstorm Watch: Tells you when and where severe thunderstorms are likely to occur. Watch the sky and stay tuned to KNTU to know when warnings are issued.
- Severe Thunderstorm Warning: Issued when severe weather has been reported by spotters or indicated by radar.
- Tornado Watch: Tornadoes are possible in your area. Remain alert for approaching storms.
- Tornado Warning: A tornado has been sighted or indicated by weather radar.
Severe Thunderstorms:The National Weather Service considers a thunderstorm severe if it produces hail at least 3/4-inch in diameter, winds of 58 mph or stronger, or a tornado.
Thunderstorms always contain lightning:
- Lightning causes an average of 80 fatalities and 300 injuries each year.
- Lightning occurs in all thunderstorms; each year lightning strikes the Earth 20 million times.
- The energy from one lightning flash could light a 100-watt light bulb for more than 3 months.
- Most lightning fatalities and injuries occur when people are caught outdoors in the summer months during the afternoon and evening.
- Lightning can occur from cloud-to-cloud, within a cloud, cloud-to-ground, or cloud-to-air.
- Many fires in the western United States and Alaska are started by lightning.
- The air near a lightning strike is heated to 50,000°F - hotter than the surface of the sun! The rapid heating and cooling of the air near the lightning channel causes a shock wave that results in thunder.
How far away is the Thunderstorm?Count the number of seconds between a flash of lightning and the next clap of thunder. Divide this number by 5 to determine the distance to the lightning in miles.
30/30 Lightning Safety Rule:
- Go indoors if, after seeing lightning, you cannot count to 30 before hearing thunder.
- Stay indoors for 30 minutes after hearing the last clap of thunder.
Lightning Myths and Truths:
- Myth: If it is not raining, then there is no danger from lightning.
- Truth: Lightning often strikes outside of heavy rain and may occur as far as 10 miles away from any rainfall. This is especially true in the western United States where thunderstorms sometimes produce very little rain.
- Myth: The rubber soles of shoes or rubber tires on a car will protect you from being struck by lightning.
- Truth: Rubber-soled shoes and rubber tires provide NO protection from lightning. The steel frame of a hard-topped vehicle provides increased protection if you are not touching metal. Although you may be injured if lightning strikes your car, you are much safer inside a vehicle than outside.
- Myth: People struck by lightning carry an electrical charge and should not be touched.
- Truth: Lightning-strike victims carry no electrical charge and should be attended to immediately. Contact your local American Red Cross chapter for information on CPR and first aid classes.
- Myth: “Heat lightning” occurs after very hot summer days and poses no threat.
- Truth: “Heat lightning” is a term used to describe lightning from a thunderstorm too far away for thunder to be heard.
Severe Thunderstorms sometimes produce large hail:
- Hail causes more than $1 billion in damage to property and crops each year.
- Large stones fall at speeds faster than 100 mph.
- Strong rising currents of air within a storm, called updrafts, carry water droplets to a height where freezing occurs.
- Ice particles grow in size, becoming too heavy to be supported by the updraft, and fall to the ground.
Severe Thunderstorms also can cause flash flooding:
- Flash floods and floods are the #1 cause of deaths associated with thunderstorms...more than 140 fatalities each year.
- Most flash flood fatalities occur at night and most victims are people who become trapped in automobiles.
- Six inches of fast-moving water can knock you off your feet; a depth of two feet will cause most vehicles to float.
Severe Thunderstorm can also produce strong winds:
- Straight line winds are responsible for most thunderstorm wind damage.
- Winds can exceed 100 mph!
- One type of straight-line wind, the downburst, is a small area of rapidly descending air beneath a thunderstorm.
- A downburst can cause damage equivalent to a strong tornado and can be extremely dangerous to aviation.
- A “dry microburst” is a downburst that occurs with little or no rain. These destructive winds are most common in the western United States.
And Severe Thunderstorms can cause tornadoes:
- Although tornadoes occur in many parts of the world, they are found most frequently in the United States.
- In an average year, 1,200 tornadoes cause 70 fatalities and 1,500 injuries nationwide.
- A tornado is a violently rotating column of air extending from a thunderstorm to the ground.
- Tornadoes may appear nearly transparent until dust and debris are picked up or a cloud forms within the funnel.
- The average tornado moves from southwest to northeast, but tornadoes have been known to move in any direction.
- The average forward speed is 30 mph but may vary from nearly stationary to 70 mph.
- The strongest tornadoes have rotating winds of more than 250 mph.
- Tornadoes can accompany tropical storms and hurricanes as they move onto land.
- Waterspouts are tornadoes which form over warm water. They can move onshore and cause damage to coastal areas.
- Tornadoes can occur at any time of the year.
- Tornadoes have occurred in every state, but they are most frequent east of the Rocky Mountains during the spring and summer months.
- In the southern states, peak tornado occurrence is March through May, while peak months in the northern states are during the late spring and summer.
- Tornadoes are most likely to occur between 3 and 9 p.m. but can happen at any time.
Tornado Myths and Truths:
- Myth: Areas near lakes, rivers, and mountains are safe from tornadoes.
Truth: No place is safe from tornadoes. A tornado near Yellowstone National Park left a path of destruction up and down a 10,000 foot mountain.
- Myth: The low pressure with a tornado causes buildings to “explode” as the tornado passes overhead.
Truth: Violent winds and debris slamming into buildings cause most structural damage.
- Myth: Windows should be opened before a tornado approaches to equalize pressure and minimize damage.
Truth: Leave the windows alone. The most important action is to immediately go to a safe shelter.
- Myth: If you are driving and a tornado is sighted, you should turn and drive at right angles to the storm.
Truth: The best thing to do is to seek the best available shelter. Many people are injured or killed when remaining in their vehicles.
Check out our Ozone Chart, Heat Index Chart, and Wind Chill Chart.
- Myth: People caught in the open should seek shelter under highway overpasses.
Truth: Take shelter in a sturdy reinforced building if at all possible. Overpasses, ditches, and culverts may provide limited protection from a tornado, but your risk will be greatly reduced by moving inside a strong building.