Thunderstorms are defined as convective storms that usually cover a relatively small geographic area, or move in a narrow path, and are sufficiently intense to threaten life and/or property. Examples include severe thunderstorms with lightning, thunder, large hail, damaging wind, or tornadoes.
A severe thunderstorm can produce a tornado, winds of at least 58 mph (50 knots), and/or hail at least 1" in diameter. A thunderstorm wind equal to or greater than 40 mph (35 knots) and/or hail of at least 1" is defined as approaching severe.
A watch is used when the risk of a hazardous weather or hydrologic event has increased significantly, but its occurrence, location, and/or timing is still uncertain. It is intended to provide enough lead time so that those who need to set their plans in motion can do so.
A warning is issued when a hazardous weather or hydrologic event is occurring, is imminent, or has a very high probability of occurring. A warning is used for conditions posing a threat to life or property.
When Thunder Roars, Go Indoors
According to the National Oceanic and Atmospheric Administration (NOAA), each year in the United States, more than 400 people are struck by lightning. On average, between 55 and 60 people are killed; hundreds of others suffer permanent neurological disabilities. Most of these tragedies can be avoided with a few simple precautions. When thunderstorms threaten, get to a safe place. Lightning safety is an inconvenience that can save your life.
Avoid the Lightening Threat
- Have a lightning safety plan. Know where you'll go for safety and how much time it will take to get there. Make sure your plan allows enough time to reach safety.
- Postpone activities. Before going indoors, check the forecast for thunderstorms. Consider postponing activities to avoid being caught in a dangerous situation.
- Monitor the weather. Look for signs of a developing thunderstorm such as darkening skies, flashes of lightning, or increasing wind.
- Get to a safe place. If you hear thunder, even a distant rumble, immediately move to a safe place. Fully enclosed buildings with wiring and plumbing provide the best protection. Sheds, picnic shelters, tents, or covered porches do NOT protect you from lightening. If a sturdy building is not nearby, get into a hard-topped metal vehicle and close all the windows. Stay inside until 30 minutes after the last rumble of thunder.
- If you hear thunder, don't use a corded phone except in an emergency. Cordless phones and cell phones are safe to use.
- Keep away from electrical equipment and wiring.
- Water pipes conduct electricity. Don't take a bath or shower or use other plumbing during a storm.
Although high winds are normally associated with thunderstorms, tornado, or hurricane activities, micro/downbursts and sustained high winds can happen anytime.
In most cases, the same safety precautions most often identified for tornado safety can be readily applied in response to high wind threats. For example:
- Stay in an interior room or basement of your house/business. Interestingly, according to high wind preparedness experts, garage doors are often the first feature in a home to fail due to high winds.
- Avoid windows.
- Do not remain in light or poorly constructed structures that may be subject to blow down or collapse.
- Stay out of structures with wide, free-span roofs like auditoriums and gyms. Secure or move indoors all items which could become projectiles.
- Avoid areas/structures immediately subject to tree/bench falls (special note: pine beetle-kill forest areas are uniquely subject to blow-down due to dried or damaged root systems).
And, as always, keep up with developments from the National Weather Service online or on the radio.
Hail Safety Tips
If you are in an automobile:
- Stop driving. If you can see a safe place close by (like the inside of a garage, under a highway overpass, or under a service station awning), drive there as soon as you can. Make sure you pull completely off the highway.
- Do NOT leave the vehicle until it stops hailing. Your car will furnish reasonable protection.
- Stay away from car windows. Cover your eyes with something (such as a piece of clothing). If possible, get onto the floor face down or lie down on the seat with your back to the windows. Put very small children under you and cover their eyes.
If you are in a building:
- Stay inside until the hail stops.
- Stay away from the windows, especially those being struck by hail.
- Account for all family members, building occupants, pets, etc.
- Do not go outside for any reason. Large hail can cause serious or even fatal injuries.
- Avoid using phones and electrical appliances during a severe storm to avoid the danger of electrocution from lightning.
If you are outdoors:
- If you are caught outdoors, seek shelter immediately. If you can't find something to protect your entire body, at least find something to protect your head.
- Stay out of culverts and lowland areas that might fill suddenly with water.
- Trees are a last resort. It is common during severe storms for trees to lose branches. Also, large isolated trees attract lightning.
Colorado Division of Emergency Management
For more on preparing yourself and your family for disaster, be sure to visit READYColorado