4.5.2013 Thunderstorm Safety Questions or Comments? Contact us at firstname.lastname@example.org
We’re entering the time of year where thunderstorms will be rumbling regularly across most parts of the United States. We have already seen some large outbreaks of thunderstorms, and a few tornadoes. We thought we would give you a few simple safety tips, to protect yourself from one of nature’s most beautiful, and deadly, phenomena.
The main threats from thunderstorms are: Lightning, Hail, Straight-Line Winds, Down-Bursts, Heavy Rain and Flash floods. Thunderstorms are fairly well predicted, however their strength and speed can change rapidly. Your best initial defense is to keep tabs on your local weather forecast each morning. If thunderstorms are in the forecast, then you’ll know to be on the lookout. Every day, the Storm Prediction Center in Norman, OK issues a thunderstorm outlook, and we always mention that in our Tweets here at The Storm Report. So, we encourage you to subscribe on our home page. Having a “heads-up” to threatening weather gives you a huge advantage in preparedness.
Next, you should have a plan for safety at work, home and while driving. When big thunderstorms threaten your area, the best place to be is inside a strong structure on the ground floor. This protects you from lightning and hail. Most office buildings are not constructed on flood plains, so you should be safe from flash flooding at your workplace. It’s also a good idea to have one or two employees serve as “weather marshals”. That is, a couple of responsible people who can keep an eye on the forecasts, and NOAA weather radio for bulletins. When thunderstorms appear imminent, your Weather Marshals would check in with all employees to make sure they’re aware of the situation, and prepare them to take action on the office emergency plan.
It’s basically the same situation at home. During a thunderstorm, located yourself and your family in an enclosed room with no windows on the lowest floor of your house. This generally keeps you safe from most thunderstorm threats.
If you work outside, your best shelter would be an enclosed vehicle. (not a motorcycle or convertible car). An enclosed car or truck acts like a shield against lightning, directing the energy around the car and down into the ground. It may be scary, but it’s better protection than being outside. If you work in construction, or near lakes or rivers, be aware that flash flooding can happen very quickly, and be prepared to move to high ground when you see water rising.
Lightning is the most deadly threat from any thunderstorm. It is unpredictable and very powerful. If you’re outside playing golf or other sports, head to a substantial structure before the storm hits. And keep in mind, lightning can strike many miles away from the center of the thunderstorm. Meteorologists call this a “Bolt From The Blue”. It’s rare, but it does happen. Employ the 30/30 rule for lightning. When you see a flash of lightning, begin counting until you hear the thunder. Every five second equals roughly one mile. So if you count to ten before hearing thunder, the lightning strike was about two miles away. If you hear thunder before counting to 30, it’s time to take shelter. The other part of the 30/30 rule is to wait 30 minutes after hearing the last rumble of thunder before resuming outdoor activities.
Hail can be a threat as well, especially if large hailstones are falling and you are caught outside. There has only been one recorded fatality in history from someone being hit by a hailstone. The biggest problem is trying to drive on it; it’s like driving on marbles. So, you will want to pull over and wait out the storm, or drive extremely carefully through hail.
Flash flooding is of particular danger to people camping in the wilderness near rivers or creeks, or in dry flood beds. It’s also dangerous for drivers because of potential road wash-outs or overflow. If you’re caught outside and heavy rain begins, move immediately to higher ground. A thunderstorm can be dropping heavy rain many miles upstream, and that rushing water can cause major problems for anyone downstream. The Big Thompson Canyon flood in Colorado in the 1970s is a prime example. People many miles downstream were caught unaware, because the storm itself was miles away. Be prepared to move quickly to higher ground.
If you are driving, and come across water rushing across the road, do not attempt to cross it, even if it does not appear to be very deep. A mere 2 inches of rushing water can float a car off the road, and into a gully or ravine where you could be trapped. Or, the roadway may be ready to collapse under the weight of your vehicle, leaving you in an extremely dangerous situation. The general rule is: “Turn Around, Don’t Drown”. If water is rushing across the road in front of you, go back the way you came and avoid crossing it.
As for down-bursts and straight-line winds, in many thunderstorms wind speeds of 70 to 90 mph are possible as the storm’s gust-front crosses your location. Down-bursts happen when heated air rises up the thunderstorm updraft in large quantity. Once the moisture (and its latent heat) are condensed, the air cools rapidly and begins a long descent, picking up speed along the way. Once that cool air hits the surface, it has nowhere to go except out along the ground. Down-burst wind speeds over 100 mph have been recorded. Being in a sturdy structure will protect you from these threats.
We must emphasize that being prepared is your first, best defense. Don’t get caught unaware. Check the weather forecasts daily, and know what your area may be expecting later in the day.
In our next article, we’ll cover Tornado Safety.
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