An unofficial term, gustnado is short for a gust-front tornado. Often confused with a standard tornado, a gustnado is the result of a localized downburst outflow of wind from a thunderstorm, whereas tornadoes are up-flow style mesocyclones. Like tornadoes, gustnadoes are most common in the Midwestern United States. On Aug. 13, 2011 a suspected gustnado caused a stage collapse at the Indiana State Fair in Indianapolis, killing five people. Gustnadoes are similar in formation to whirlwinds or dust devils and may last from seconds to minutes. Sustained winds from gustnadoes may reach wind speeds of 60 to 80 mph, similar to that of an F0 or F1 tornado.
4. Rogue Wave
Once thought to be mythical, rogue waves are abnormally large waves that occur seemingly out of nowhere. Also referred to as “freak” or “monster” waves, reports of rogue waves have persisted for years. Rogue waves entered the scientific lexicon when a huge 84-foot wave was measured passing a drilling platform in the North Sea on Jan. 1, 1995. A rogue wave is likely caused by the interaction of currents and wind, focusing to produce one large wave front. These are different than the waves generated by a tsunami, which are produced by an underwater seismic event, or more rarely by a rockslide or sea stack collapse. Whatever their origin, rogue waves are believed to have caused many ship disasters through the centuries, including the mysterious loss of the SS Edmund Fitzgerald in 1975 on Lake Superior. Rogue waves have also claimed victims on land; in early July 2012, a rogue wave struck a group of teen kayakers as they took a break 50 feet inland along the coast of Hawaii’s Big Island, sweeping one boy out to sea. The European Space Agency is currently working on methods to analyze and predict the appearance of these rare and monstrous waves.
Meaning “straight” or “direct” in Spanish, the weather phenomenon known as a derecho made headlines June 29, 2012 when a strong storm line caused heavy damage along a path from Indiana to the mid-Atlantic Coast, killing 22 people and causing power outages for millions. Derechos are extended patterns of straight-line winds that move in front of large storm convection cells, creating hail and damaging winds. Also a downburst style outflow like a gustnado as opposed to an upflow of air as seen in a tornado, derechos have minimum wind speeds of 58 mph but can reach sustained winds of more than 100 mph. Conditions for a derecho are ripe when a rain-cooled downdraft of air collides with a warm upflow, feeding it horizontally along a bow-shock shaped front. In fact, derechos have a signature bow shape to them on Doppler radar, and long lines of banded horizontal clouds known as arcus are associated with their formation.
2. White Squall
Still a controversial meteorological phenomenon, thought by many to be a myth, a white squall is characterized as an abrupt and fierce windstorm that arises in an instant. White squalls aren’t associated with rain or storms and may arise on a clear, cloudless day at sea. Although mariners around the world have told tales of white squalls, the phenomenon is most widely reported on the Great Lakes. Famous sinkings such as the Hunter Savidge in 1899 on Lake Huron, the SS Edmund Fitzgerald (see No. 4 above) and the Albatross off of the Dry Tortugas in the Caribbean in 1961 have all been attributed to a white squall. The fate of the Albatross was even fictionalized in the 1996 film, White Squall. The phenomena may well be associated with what is known as a dry microburst, or a sudden down-welling and outflow of super-cooled air.
This occurs when an inferno becomes so intense that the heat rising from it begins to fuel its own sustained wind system. In the case of forest fires, this kind of convection can be set up when daytime heating rises up a burning mountainside, feeding oxygen to a fire. Many smoke jumpers and firefighters have died in firestorms over the years, as they are impossible to outrun. In 2003, a firestorm completely destroyed the Mount Stromlo observatory complex in Australia as it swept up the mountainside; the staff had a mere 20 minutes to evacuate. Firestorms can also be triggered by mass bombing raids, such as occurred during the infamous incendiary firebombing of Dresden, Germany by Allied forces in 1945. That raid burned an area of eight square miles and left 25,000 civilians dead. The blast from the atomic bomb dropped on Hiroshima, Japan, also triggered a firestorm around ground zero. As current drought conditions persist across the United States, the potential exists for more wildfires to evolve into firestorms.
One More: Dust Storm
In dry arid regions such as the Southwestern U.S. or the Middle East, windstorms can pick up small dust particles that eventually build into region-engulfing dust storms. A particular type of dust storm known in Arabic as a haboob can become a self-sustaining wall of dirt that can drop dirt in amounts similar to a heavy snowfall. Though generally not fatal, prolonged exposure to a dust storm can cause life-threatening respiratory and health issues, and such storms have been blamed for fatal traffic accidents.