A what? An exciting bit of weather action

Derecho radar
The derecho of June 29, 2012 was quite an event, as this radar compilation shows.

I don’t spend much time watching TV news but my wife keeps it playing at times. I kept overhearing a new word (to me) after the June 29th storm that turned out lights from the middle west to the East Coast. The word sounded to me like “deratio” but Wikipedia lists “de-ray-cho” as the correct pronunciation.

It is spelled “derecho” from Spanish for “straight,” and is a seldom-used meteorological term used to describe a long-lasting and severe squall line with quite strong straight line winds. The word is not often used because the events are relatively rare.

A brief definition says that it has to last six hours, cover 250 miles and have convection-induced surface winds of at least 50 knots to qualify as a derecho. The storm of June 29th beat that in spades.

According to an AccuWeather story, this storm raced 700 miles in 12 hours. Wind reports were numerous but one of the first was at Ft. Wayne, Indiana, at 91 mph and one of the last was 81 mph at Tuckerton, New Jersey about 12 hours later. Damage was especially bad in the Washington, D. C. metro area where hundreds of thousands were left without power for days.

When big storms like this rage, we usually lose some general aviation airplanes in serious weather accidents. Fortunately this didn’t happen on June 29th. There were probably some airplanes damaged on the ground but that only hurts financially.

If you want to be a weather geek for a few minutes, there is neat stuff available by checking “derecho” on Google. Some radar images are there and the appearance of these is such that nobody in their right mind would have even thought about trespassing in an airplane.

Had you ever heard of a derecho before?

5 Comments

  • Richard,

    I happened to get an up close and personal view of the weather that day. We had departed KBUF enroute to KUMP (Indy Metro) around 1:30PM with an estimated enroute time of 2:30 and started watching the storm on Nexrad soon after. The line of wx was just starting to move out of IL on a E-NE path, and didn’t appear that it would have much impact on our flight route as it seemed it would all stay north of our route. During the flight, the weather movement to the east started to accelerate and expand southwards rapidly. We met the line of weather just east of the OH border pretty much north of Dayton and diverted to the south to work around the weather still expecting to get in to UMP.

    By the time we turned south, we started to have multiple cells developing east and south of our position. Fortunately, we still had room to maneuver and keep the windsreen pretty dry as we worked ourselves out of the weather. By now the weather stretched across Indiana and was well into Ohio. The weather sagged south and engulfed Indy, shutting down the International Tower for a few minutes. We diverted to KBMG to wait it out.

    In 40 years of flying, I have never seen a squall line expand and intensify as this one did so I’m glad to learn it has a special name. 60 minutes later we departed KBMG and had a smooth flight back into Indy Metro.

    Regards,

    Bob Luhrs

  • Another hidden from the general public story behind any significant weather event like this one is the toll it takes on GA equipment even when properly secured. Our aero club had 10 aircraft available prior to the storm and was down to six after it blew through. One aircraft, a venerable former USAF Academy T-41C is a writeoff and the other three are in long term repair as our club has funds. All were properly secured on the ramp but Mother Nature has little respect for the works of mankind.

  • Richard,
    These type winds are not a surprise here in KS. Not every year but often enough to get your attention.

    Have not seen one as mean as the East Coast Monster though.

  • I read an announcement from NOAA the week before that talked about a few new terms they added to the nomenclature. That was the first time I had heard the term derecho.

    One airport I fly at had multiple aircraft damaged. While the other had a little damage to a building, but none to aircraft. Luck of the draw.

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