Severe Thunderstorm Watches and Warnings
A severe thunderstorm watch is issued by the National Weather Service when the weather conditions are such that a severe thunderstorm (damaging winds 58 miles per hour or more, or hail three-fourths of an inch in diameter or greater) is likely to develop. This is the time to locate a safe place in the home and tell family members to watch the sky and listen to the radio or television for more information.
A severe thunderstorm warning is issued when a severe thunderstorm has been sighted or indicated by weather radar. At this point, the danger is very serious and everyone should go to a safe place, turn on a battery-operated radio or a television, and wait for the storm to pass.
Outdoor Safety During a Severe Thunderstorm
- Attempt to get into a building or car. Rubber-soled shoes and tires provide no protection from lightning.
- If no structure is available, get to an open space and squat low to the ground (hands on knees) as quickly as possible. (If in the woods, find an area protected by low clump of trees – never stand underneath a single large tree in the open.) Be aware of the potential for flooding in low-lying areas such as arroyos, ditches and canyons.
- Avoid tall structures such as towers, tall trees, fences, telephone lines, or power lines.
- Stay away from natural lightning rods such as golf clubs, tractors, fishing rods, bicycles, or camping equipment.
- Stay away from rivers, lakes, or other bodies of water.
- If you are isolated in a level field and you feel your hair stand on end (which indicates that lightning is about to strike), bend forward, putting your hands on your knees. A position with feet together and crouching while removing all metal objects is recommended. Do not lie flat on the ground.
Estimating Distance From A Thunderstorm: Because light travels much faster than sound, lightning flashes can be seen long before the resulting thunder is heard. Estimate the number of miles you are from a thunderstorm by counting the number of seconds between a flash of lightning and the next clap of thunder. Divide this number by five.
Important: You are in danger from lightning if you can hear thunder. Knowing how far away a storm is does not mean that the danger is only when the storm is overhead.
The 30/30 Lightning Rule: Go inside or get in your vehicle if, after seeing lightning, you cannot count to 30 before hearing thunder. Stay inside 30 minutes after hearing the last clap of thunder.
Winds: Summer storm formations always bring winds with them here, even though they sometimes drop little rain. Winds of anywhere from 15-40 mph are common, and up here in the mountains, they seem to blow in every direction. If you or your children are outdoors, avoid as much as possible being near dead or dying trees when winds are strong. These trees can fall without warning anyway, and high winds only increase the potential for tree falls.
More information: http://www.fema.gov/hazard/thunderstorm/th_before.shtm or http://www.lightningsafety.noaa.gov/.