The Woodward News

Local News

July 28, 2013

Derechos are not uncommon

Woodward, Okla. — Derecho (dā-rā-chō) is the Spanish word for "straight."

It is also, fittingly, a term used by meteorologists to label a certain type of windstorm that produces widespread and sustained straight-line damaging winds.

One of these windstorms struck the northeast part of the state earlier this week, sweeping through with wind speeds up to 80 mph, which led to more than 100,000 power outages in Tulsa County alone as it snapped power lines and felled trees.

While derecho type windstorms are not frequent, they are also not that uncommon for this time of year or in this part of the country.

"They're fairly common especially in the late summer months across the northern plains," said Ryan Barnes, a meteorologist with the National Weather Service in Norman.  "But they can come as far south as here and can develop almost anywhere.  But generally it's in the plains where they are common.  It has to do with storms systems and the patterns that are set up."

Matt Lehenbauer, director of Woodward County Emergency Management, agreed that derechos are common across the Great Plains during the months of June, July and August.

"We usually see one or 2 sweep through the region every summer," Lehenbauer said.

Barnes explained that a common derecho-producing weather pattern will be a system that moves out of Canada and south across the plains to combine with the moisture "that's usually in place across the plains," resulting in the formation of large storm complexes.

"Basically a derecho is due to very heavy rainfall associated with a large storm complex," he said.  "It's a little more complicated than that, but basically air rushes very quickly to the ground and then spreads out rapidly from the complex."

Just how fast are these rushing winds?

"Usually you'll see with derechos the wind can be anywhere from 70 mph to 90 mph.  They can even exceed 100 mph as well," Barnes said.  "They can be just as dangerous as tornadoes, the small or weaker tornadoes."

Lehenbauer said that sometimes a derecho storm can even spawn some lower level EF-0 or EF-1 tornadoes.

"However, it's often hard to see these types of tornados on radar because of all other wind activity going on and they're hard to prove, unless someone sees them, because it's hard to separate the damage from that caused by the straight-line winds alone," Lehenbauer said.

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