F5 Tornado, Kansas 7th May 2007

sirpsycho

From google news:
Residents briefly returned to the ruins of Greensburg, Kansas, on Monday three days after a tornado with 205 miles per hour (330 kilometres per hour) winds tore through the area, levelling the small town and killing at least 12 across the state.

"It's been one of the most destructive tornadoes in the last 10 years," said meteorologist Matt Gerard at the National Weather Service.

The 2.7 kilometre wide (1.7 mile) twister was classified as an F-5 on the enhanced Fujita scale, meaning the damage it caused was consistent with gusts that sustained an average speed of 200 mph (320 km/h) over a period of three seconds. The Greensburg tornado was part of a storm front that whipped through Kansas, spawning dozens of tornadoes - as well as Illinois, Oklahoma, South Dakota and Nebraska, where damage was less severe.

The tornado hit Greensburg at about 21.45 (local time) on Friday and stayed on the ground about an hour, travelling about 22 miles (35 km). A warning siren sounded about 20 minutes before the tornado hit Greensburg, prompting those residents who could to take shelter in their basements.

Residents were allowed until dusk on Monday to retrieve mementos and assess of the levels of damage to homes and businesses – 95% of buildings in the town were destroyed. Meanwhile, search and rescue crews continued to comb through the rubble looking for the dead and injured as state Army National Guard troops and heavy equipment were rushed into the remains of the south-central Kansas farming community.
Iraq shortages

The twisters were accompanied by widespread flooding on Sunday and Monday that required more than 200 water rescues, closed many roads and shuttered several schools in another part of the state.

Much of the equipment that the state would normally use – helicopters, Humvees and trucks controlled by the state's Army National Guard – has been sent to the war in Iraq, authorities said.

"There is no doubt at all that this has slowed down and hampered the recovery," said Kansas Governor Kathleen Sebelius. "Not having this equipment in place all over the state is a huge handicap."
Improving forecasts

The tornado struck in an area of the central US known as Tornado Alley, which encompasses parts of a half-dozen states. It is prone to the destructive "funnel clouds" that kill an average of 70 Americans each year, prompting calls for better prediction technology.

Wind speed in tornado forecasting is measured using Doppler radar that bounces off moving raindrops. The alarm is sounded if a pattern in speed emerges that is characteristic of a tornado.

Using current radar technology, predicting tornadoes further in advance would increase the likelihood of a false alarm, says Howard Brooks of the National Severe Storms Laboratory in Norman, Oklahoma.

However he hopes new technology that allows wind speed to be measured every minute instead of every six will allow earlier prediction with the same accuracy. “We may see things earlier because we sample more frequently,” he says.

Pictures of damage done