Derechoes have been in the news in Washington as of late. No, that’s not some new breed of super bureaucrat, but it is something from a supercell sized thunderstorm that crossed several states during its lifetime. You may have seen this NOAA image already on a few news websites:
That’s a time lapse radar image capture as the storm progressed from near Chicago to Chesapeake Bay.
They’ve been known over a century, and around far longer than that. Wikipedia says that Derecho comes from the Spanish word for “straight”.The word was first used in the American Meteorological Journal in 1888 by Gustavus Detlef Hinrichs in a paper describing the phenomenon and based on a significant derecho event that crossed Iowa on 31 July 1877.
They were further refined with the advent of weather radar. Derechos are typically bow or spearhead-shaped on weather radar, and hence they are also called a bow echo or spearhead radar echo. Here’s a WSR-57 radar image from Cleveland, Ohio in 1969:
July 4, 1969 “The Ohio Fireworks Derecho” spanning MI, OH, PA, WV
They are fairly common meteorological events, occurring from May to August, peaking in frequency during the latter part of June into July. According to NOAA’s Storm Prediction Center, the Washington DC area gets a derecho about once every four years:Here’s a few of the past logged by the Storm Prediction Center.
NOTEWORTHY DERECHOS IN RECENT DECADES
Many significant derechos (i.e., those that have caused severe damage and/or casualties), have occurred over North America during the last few decades. Most of these affected the United States and Canada. Listed below is a selection of some of the more noteworthy events in recent years; the list is not all-inclusive. Information provided in the links includes a map of the area affected, and a description of the storm’s impact.
Holiday weekend events
The human impact of the following events was enhanced by their occurrence on summer holiday weekends, causing many to be caught out-of-doors during the sudden onset of high winds…
July 4, 1969…………….”The Ohio Fireworks Derecho”….MI, OH, PA, WV
July 4, 1977…………….”The Independence Day Derecho of 1977″….ND, MN, WI, MI, OH
July 4-5, 1980…………”The ‘More Trees Down’ Derecho”….NE, IA, MO, IL, WI, IN, MI, OH, PA, WV, VA, MD
Sept. 7, 1998………….”The Syracuse Derecho of Labor Day 1998″….NY, PA, VT, MA, NH
Sept. 7, 1998 …………”The New York City Derecho of Labor Day 1998″….MI, OH, WV, PA, NJ, NY, CT
July 4-5, 1999…………”The Boundary Waters-Canadian Derecho”….ND, MN, ON, QB, NH, VT, ME
The derechos of mid-July 1995
The mid-July 1995 derechos were noteworthy for both their intensity and range…
Series Overview……….Montana to New England
July 12-13, 1995……..”The Right Turn Derecho”….MT, ND, MN, WI, MI, ON, OH, PA, WV
July 14-15, 1995……..”The Ontario-Adirondacks Derecho”….MI, ON, NY, VT, NH, MA, CT, RI
Two well-documented, classic events over the eastern United States…
April 9, 1991……………”The West Virginia Derecho of 1991″….AR,TN, MS, AL, KY, IN, OH, WV, VA, MD, PA
March 12-13, 1993….”The Storm of the Century Derecho”….FL, Cuba
“Southward burst” is a term coined by Porter et al. in a 1955 paper (see reference here) to describe a progressive-type squall line that surges rapidly southward rather than east…
May 4-5, 1989…………”The Texas Derecho of 1989″….TX, OK, LA
May 27-28, 2001……..”The People Chaser Derecho”….KS, OK, TX
Other noteworthy events
June 7, 1982…………..”The Kansas City Derecho of 1982″….KS, MO, IL
July 19, 1983…………..”The I-94 Derecho”….ND, MN, IA, WI, MI, IL, IN
May 17, 1986………….”The Texas Boaters’ Derecho”…..TX
July 28-29, 1986……..”The Supercell Transition Derecho”….IA, MO, IL
July 7-8, 1991………….”The Southern Great Lakes Derecho of 1991″….SD, IA, MN, WI, MI, IN, OH, ON, NY, PA
May 30-31, 1998……..”The Southern Great Lakes Derecho of 1998″….MN, IA, WI, MI, ON, NY
June 29, 1998………….”The Corn Belt Derecho of 1998″….NE, IA, IL, IN, KY
July 22, 2003……………”The Mid-South Derecho of 2003″….AR, TN, MS, AL, GA, SC
May 8, 2009…………….”The ‘Super Derecho’ of May 2009″….KS, MO, AR, IL, IN, KY, TN, VA, WV, NC
Here, thanks to modern radar technology and people who are interested enough to track storms on radar from start to finish, we have this life cycle of the derecho:
Timelapse of closest NEXRAD base reflectivity of the 29 June 2012 derecho. The timelapse moves from Davenport, Iowa to Richmond, Virginia over 14 hours.
Here’s a cross section, showing how the mesoscale thunderstorm dynamics make that bow echo. Image courtesy of the NOAA Storm Prediction Center page about derechoes:
What is troubling about this being linked to “global warming” is the Washinton Post Capital Weather Gang’s story by Jason Samenow, which ends with this gem:
As the intensity of the heat wave, without reservation, was a key factor in the destructiveness of this derecho event – it raises the question about the possible role of manmade climate warming (from elevated greenhouse concentrations). It’s a complicated, controversial question, but one that scientists will surely grapple with in case studies of this rare, extraordinary event.
Yet Samenow cites the same sources from the Storm Prediction Center page that I do, showing the exact same image above (after editing out the number 3). Yet somehow, he managed to conveniently ignore the historical context and the climatological frequency of derechoes on that page.
He’s gets the coveted WUWT Double BS award for his sloppy journalism.
Joe D’Aleo has more on the derecho event here at ICECAP.
UPDATE: I made an error. I got two different posts mixed up related to the heatwave, conflating the quote discussing the heat wave by Doug Kammerer (with thunderstorm radar loop in background video by Karins on the CP post) . I’ve removed the citation (and video) related to NBC Bill Karins quoted on Climate Progress. My sincere apologies for the error. My only defense is that I don’t listen to audio much anymore due to my hearing issues. Thankfully, I’ve got a big group of people that will let me know immediately that I’ve made an error, and thus I’ve heeded their advice and fixed the error within minutes of this posting. Thank you. – Anthony