Severe Storms…Or Are Your Trees Weak?

Monday storms brought plenty of wind to go with the lightning.

By: Dan Bickford | News Channel 7
Published: July 22, 2008 | 0 Comments | Post a Comment

The strong to severe storms that blew through on Monday certainly brought quite a bit of wind…damaging for some, just a little frightening for others. Many of these storms were truly “severe”; severe thunderstorm warnings are issued for any storm that can produce hail ¾” in diameter or larger, or winds of 58 mph or greater. No…the rate at which you see lightning or get heavy rain does not factor into this at all. Regardless, we saw storms on Monday that certainly fit the wind criteria.
How do we know what the winds speeds are in these stronger storms? Well for many storms, we don’t know for sure. Doppler radar (and our Live VIPIR system) can alert us to where the potential for strong winds lies…and can give us rough estimates as to what we’re looking for in terms of speed. The only way to directly verify those speeds is to have the storm move over a weather station so we can get a direct speed recording.
There is an indirect way: by looking at wind damage. It has generally been accepted that once the winds clears 58 mph, we are more likely to see large tree limbs break off, and greater potential for damage to billboards, awnings, and some roofing. In areas of lower population density, tree damage may be the only way to determine a storm’s severity.
Here’s the problem: forestry officials in the Southeast point out the drought-stricken trees are more susceptible to the ravages of nature. Damage that could occur to a healthy tree in a 58 mph wind might occur at a much lesser speed in a weakened tree. So if 45-50 mph winds take down a weakened tree, does that make a storm severe? By definition, no. In “after-the-fact” checks of area storm damage however, such damage may earn these storms severe classification, whether the storm “earned” it or not.
Assuming we stay in a similar overall weather pattern for the rest of the summer…a lot of dry weather broken up by occasional afternoon thunderstorms…don’t be surprised if it seems like you’re hearing about more severe weather than you used to under similar weather conditions. The storms aren’t necessarily stronger; your trees may be weaker.