April 23, 2013...
Added close-up radar reflectivity and velocity views of the northern-most bow echo of the April 19-20, 2011 Ozarks / Ohio Valley derecho.

November 7, 2012...
Added description of the April 19-20, 2011 Ozarks / Ohio Valley derecho, one of more notable though largely forgotten serial-type derechos in recent years.

October 21, 2012...
Added description of the July 10-11, 2011 Cross Country derecho that affected areas from eastern Colorado to Maryland during a twenty-four hour period.

September 3, 2012...
Added citations to References.

August 28-29, 2012...
Added text and radar animations, and modified schematics in Serial and Progressive Derechos; modified text and re-drew schematic panel in Supercells.

August 23-26, 2012...
Added section on mesovortices to Tornadoes and Other Circulations in Derecho Environments, and made numerous related minor edits to Derecho Facts page; replaced image and added reference, Fujita and Wakimoto 1981, to Downbursts; added text, modified one image, and added another to Bow Echoes and Bookend Vortices.

August 21, 2012...
Added surface and 500 mb analyses and accompanying text to July 19, 1983 I-94 derecho page.

August 17-19, 2012...
Added description of the Nov. 20, 1989 Mid-Atlantic low dewpoint derecho, an unusual event that occurred with exceedingly low moisture over the northeastern United States in late fall. Also added Figure 2 to the May 31, 1994 Utah / Wyoming derecho page.

August 13, 2012...
Added description of the May 31, 1994 Utah / Wyoming derecho, an unusual low dewpoint event that occurred over the southern Plateau. Also updated hyperlinks at conclusions of Noteworthy Event pages.

August 8, 2012...
Added visible data satellite loop of May 31, 1994 Utah-Wyoming derecho to Derecho Development, and made minor edits to same section.

July 24-26, 2012...
Updated event description, added local radar reflectivity and velocity loops, and added observed wind gusts to composite radar image in the June 29, 2012 Ohio Valley / Mid-Atlantic derecho page; made minor changes to Derecho Facts and added spatial scale to schematic figure in Derecho-producing Storms; updated destination anchors in reference links of individual "Noteworthy events" pages.

July 19, 2012...
Added Derechos and Flash Floods, and made Derechos and Heat Waves a separate section in Derecho Facts. Rearranged other subsections on Derecho Facts page, and added more discussion in Derecho Forecasting. Also added note regarding presence of mesoscale convective vortex with the June 29, 2012 Ohio Valley / Mid-Atlantic derecho, and added image, "The Line Storm," by John Steuart Curry, to opening page.

July 17, 2012...
Added description of the June 29, 2012 Ohio Valley / Mid-Atlantic derecho, perhaps the first such system to garner widespread media attention as being a derecho.

July 13, 2012...
In Derecho Forecasting, added discussion and figure on relationaship between derechos and heat waves.

July 3 - 9, 2012...
Rearranged "Introduction" and made minor modifications to "Derecho Development" and "References." Expanded discussion on hazards posed by derechos to urban areas in "Casualty and damage risks from derechos," and added section, "Derecho Forecasting". Enlarged margins and line spacing.

March 1, 2012...
Expanded "Derecho Facts" to include subsection, "Derecho development" (with figures). Also in "Derecho Facts," added information to subsections "Derecho definition," "Derecho-producing storms," and "Derecho climatology." In addition, eliminated question-answer format.

April 7, 2011...
Added visible satellite loop to the May 8, 2009 "Super Derecho" event page.

March 17 - 22, 2011...
Added a description of the May 8, 2009 "Super Derecho" that affected areas from western Kansas to the Appalachians. The associated convective system featured an unusually intense, long-lived mesoscale vortex that produced widespread wind damage independent of that produced by the system's more "conventional" band of bow echo storms.

March 15, 2011...
Added satellite imagery and re-scanned image of damage associated with the July 28-29, 1986 derecho in Iowa.

March 13, 2011...
Added a description of the June 29, 1998 derecho to "Noteworthy Derechos in Recent Decades" (formerly, "Historic Derecho Events"). This storm affected a large part of the Corn Belt and spurred interest in the origin and behavior of the small scale vortices that often appear in derecho-producing convective systems.

February 23 - March 8, 2011...
Numerous changes made to text, subject arrangement, illustrations, and hyperlinks throughout site; added information here on the impact of derechos on overhead electric distribution lines in urban areas.

February 17, 2011...
Re-arranged and updated References (formerly, "Scientific Publications").

July 22, 2010...
Added video of the July 18, 1991 derecho that affected the Pakwash forest of Ontario in "Pictures and videos of derecho events".

January 6, 2010...
Added information from a presentation by Ray Wolf of the NWS - Quad Cities on Dr. Gustavus Hinrichs, the 19th century physics professor who first used the word "derecho" to refer to convective wind storms; link to Wolf's presentation also provided. See Origin of the term "derecho".

August 18, 2009...
Added photographs and observations made by Douglas Berry related to his experience with the Ball State University storm chase team and its encounter with the May 27-28, 2001 derecho; also, added photograph by Brittney Misialek to the About Derechos opening page, showing a derecho-producing storm system moving into the Chicago area on the evening of July 10, 2008.

September 25, 2008...
Added video clip of an approaching derecho as recorded by Paul Knightley near Shattuck, Oklahoma to the May 27-28, 2001 event page.

April 12, 2006...
Information added about derechos that occurred in the United States during 2004 and 2005. This information includes maps of the derecho paths, listings of the times of occurrence, and the areas affected. Links also are provided to the Storm Prediction Center storm report archive for each event.

March 29, 2005...
Added the May 17, 1986 derecho to "Noteworthy Derechos in Recent Decades." This event is called the "Texas Boaters' Derecho" because it capsized hundreds of pleasure boats in the state. Six people drowned and more than 100 had to be rescued. The presentation includes the first-hand account of a boater on Lake Livingston that tragic day.

January 19, 2005...
The May 27-28, 2001 derecho page updated to include two gust front photographs and Doppler-on-Wheels radar images.

January 9, 2005...
Added climatological maps showing the frequency of derecho occurrence in the United States. These maps are for "moderate and high" intensity events as defined by Coniglio and Stensrud here.

December 1, 2004...
Included information about two derechos that caused widespread, long-lived power outages in metropolitan areas. One of the events occurred in Kansas City on June 7, 1982, and the other in Memphis on July 22, 2003.

November, 23, 2004...
Added personal account of the 4-5 July 1999 derecho as experienced while camping overnight in western Maine.

September 26, 2004...
Added an audio file demonstrating pronounciation of the word "derecho" to the "Derecho Definition" section of the Derecho Facts page.

August 14, 2004...
Added radar imagery and loops and explanatory text to the Quebec part of the July 4-5, 1999 Boundary Waters/Canadian derecho page.

July 21, 2004...
Three photographs and additional information added to the July 19, 1983 derecho page, showing the derecho's passage through Madison, Wisconsin. The photographs show the laminar, layered "shelf" cloud and associated gust front crossing Lake Mendota toward the University of Wisconsin campus, as well as post-derecho waves on Lake Mendota.

July 5, 2004...
Added information to the May 27-28, 2001 derecho page, explaining why this event was called the "People chaser" derecho. Also, added a paragraph describing the "haboob" that formed along the gust front during the initial stages of the event.