Tag Archives: windstorm

Did a 'gustnado' topple the stage at the Indiana State Fair?

Did a ‘gustnado’ topple the stage at the Indiana State Fair? | MNN – Mother Nature Network.

Another older post that highlights some interesting and unusual wind events….

The stage, just as it began to collapse Photo: JSilas7/YouTube
Investigators are searching for clues about the Aug. 13 stage collapse at the Indiana State Fair in Indianapolis that killed five people.

Some meteorologists think a kind of wind storm called a ‘gustnado’ could be to blame.

Cousins to tornadoes, gustnadoes are brief, low-to-the-ground swirling clouds. They are relatively weak compared to tornadoes, but they can still pack a punch and are capable of knocking over weak structures.
At the very least, the damage was caused by a strong gust front, or outflow boundary. This front is what separates thunderstorm-cooled air from the warmer air surrounding it. Gustnadoes are known to develop along gust fronts.
“The video shows a swirl of dust coming across the stage, and it’s only when the swirl hits the stage that the stage actually collapses,” according to meteorologists at AccuWeather.com. [Click here to see the video on YouTube. Warning: The footage may be considered disturbing.]
Weather slang
The gustnado designation hasn’t been given to the Indiana storm by the National Weather Service.
“Normally we don’t classify an event as a gustnado,” said Dave Tucek, a meteorologist with the NWS in Indianapolis. According to the NWS storm report, the wind gusts were estimated at between 60 and 70 mph (97 and 113 kph).
Gustnado wind speeds can reach 80 mph (129 kph), according to the National Weather Service. Winds of that speed can cause damage similar to that of an EF-0 or EF-1 tornado, the lowest rankings on the tornado damage scale.
Tucek told OurAmazingPlanet that from the videos he has watched, he does not see evidence of a swirling motion in the dust and that “it’s hard to say for sure,” whether a gustnado formed.
Investigation continues
If a tornado had struck, storm survey teams for the NWS would be investigating to determine the strength. The Indianapolis NWS station has no plans to send a team to investigate the wind damage, Tucek said. The Indiana Occupational Safety and Health Administration and the state fire marshal’s office are investigating what caused the collapse, reported the New York Times.
Telling the difference between a strong gustnado and a tornado can be tricky.
Gustnadoes may be accompanied by rain, just like tornadoes, but they are usually wispy or only visible as a debris cloud or dust whirl — a far cry from the dense and menacing funnel clouds of tornadoes.
Yet small tornadoes can seem wispy at first; the key is to look at the top of the suspected gustnado. Unlike tornadoes, gustnadoes are not connected to the storm clouds above, sticking closer to the ground.
True tornadoes spin off huge rotating storm clouds, called mesocyclones, which can tower tens of thousands of feet into the sky. Gustnadoes are more likely to be associated with a shelf cloud, a low, horizontal structure in the front of a thunderstorm.
This article was reprinted with permission from OurAmazingPlanet.

Rare 'derecho' storm sweeps across the Midwest

Rare ‘derecho’ storm sweeps across the Midwest | MNN – Mother Nature Network.

From July but still interesting….

A derecho uprooted a huge tree in Chicago, Ill. A MIGHTY WIND: A derecho uprooted a huge tree in Chicago, Ill. (Photo: DERRICKR_SMG/lockerz.com)
A severe storm is sweeping across the Midwest today with winds so strong that it has a special name: derecho.

A derecho (from the Spanish adverb for “straight”) is a long-lived windstorm that forms in a straight line — unlike the swirling winds of a tornado — and is associated with what’s known as a bow echo, a line of severe thunderstorms. The term “derecho” was first used over a century ago to describe a storm in Iowa. Across the United States, there are generally one to three derecho events each year.

The Midwest derecho has wind gusts between 60 and 80 mph (97 to 129 kph), according to the Weather Channel. Iowa, Wisconsin, Michigan and Illinois have all reported severe winds. These severe winds are the main cause of damage from the storm, said Rose Sengenberger, a meteorologist with the National Weather Service in Romeoville, Ill., but added that people should be on the lookout for other dangerous weather.
“With any long-lived storm, there is also the threat of lightning and heavy rain,” Sengenberger told OurAmazingPlanet.
Tornadoes are not any more likely during a derecho, Sengenberger said. Still, the National Weather Service issued a tornado warning for parts of southwest Michigan. Dangerous rain-wrapped tornadoes could shoot down from the squall line, said the NWS. As their name suggests, rain-wrapped tornadoes are shrouded from view by pouring rains, making them even more potentially dangerous for their ability to surprise.
A derecho is not the worst of the windstorms, however. On May 8, 2009, a rare windstorm that swept across Kansas, Missouriand Illinois was in a league of its own. An intense vortex and eyelike structure similar to what forms at the center of tropical storms and hurricanes appeared in the bow echo. The storm was so severe that it earned a brand-new name: super derecho.
The super derecho gained strength as it moved across Kansas in the early morning, spinning off 18 tornadoes and packing wind speeds from 70 to 90 mph (115 to 145 kph) when it hit Springfield, Mo. The super derecho plowed a path of destruction through the state about 100 miles (62 kilometers) wide, crossed the Mississippi River with 90 to 100 mph (145 to 160 kph) wind gusts and blew through Illinois before dissipating at that state’s eastern border.
This article was reprinted with permission from OurAmazingPlanet.