Yep..just that simple, but they can be extremely destructive. A couple of years ago I was caught in a storm with 100 mph straightline winds...it was terrifying. I saw a billboard held by 2 I beams bent double by those winds.

Duplicate post. This should get rid of it..see above for the answer. Sorry.

I'm a storm spotter with the NWS. We use the term straight line winds to mean damaging thunderstorm winds not produced by a tornado. As you may know, tornado winds twist and spin upward into the storm causing damage along the path of the twister. By comparison, straight line winds come down and out of a storm and then move out in a straight line. These winds can occur in lines of thunderstorms called squall lines, or in individual storms. When produced by the leading edge of a squall line this is usually known as a gust front. To be classified as Severe, the winds in the gust front must reach speeds of at least 58 mph. In a squall line, the downward moving air causes the storm's radar echo to resemble a bow. This is called a Bow Echo, and is usually the basis for Severe Thunderstorm Warnings involving squall lines. When you hear a Severe Thunderstorm Warning, it means damaging winds and or hail larger than a penny are about to occur, and you need to take shelter. Another type of damaging straight line winds is a downburst. We all know that thunderstorms form as an updraft of rising warm moist air rises into cooler air aloft. When the air inside the storm cools and gets heavy enough, it falls out of the storm to the ground, and spreads out in all directions. This is known as a downdraft, and is typically where rain or hail is seen coming out of the storm. When the downdraft is accompanied by damaging winds, it is called a downburst. Downbursts can be classified in several ways. For example, if the downburst is accompanied by rain, it's called a wet downburst. Conversely, if there is no rain, it's called a dry downburst. Downbursts can also be classified by the size of the area they damage. If the area damaged is larger than 2.5 square miles, we call it a macroburst. If it's smaller than 2.5 square miles, we call it a microburst. By the way, a microburst is extremely dangerous to airplanes, and many planes have been knocked out of the sky as they landed at airports during storms. To be classified as Severe, the winds in the downburst must reach speeds of at least 58 mph. Severe Downbursts can also occur over long periods of time and large areas. These are known as Derechos.