ScienceDaily (Nov. 6, 2008) — A new study by Northern Illinois University scientists underscores the danger of nighttime tornadoes and suggests that warning systems that have led to overall declines in tornado death rates might not be adequate for overnight events, which occur most frequently in the nation's mid-South region.
Over the past century, the tornado death rate has declined, in large part because of sophisticated forecasting technology and warning systems. But the researchers found that the nighttime tornado death rate over the past century has not shared the same pace of decline as the rate for daytime tornadoes.
"The proportion of nocturnal fatalities and killer tornado events has increased during the last half century," said lead author Walker Ashley, an NIU meteorologist and professor of geography. "Unfortunately, this nocturnal fatality rate appears to be a major factor for the stalled decline in national tornado-fatality tallies during the past few decades."
Ashley, NIU Geography Chair Andrew Krmenec and Research Associate Rick Schwantes published their study in the October issue of the American Meteorological Society's journal, Weather and Forecasting.
The study found that from 1950 to 2005, 27 percent of tornadoes in the United States were nocturnal, yet 39 percent of tornado fatalities and 42 percent of killer tornado events occurred at night.
Ashley predicts that annual tornado fatalities might begin to rise. In 2007 alone, 80 tornado fatalities were recorded, with 59 of those fatalities occurring between sunset and sunrise. Nineteen of 26 killer tornadoes that year occurred at night. So far this year, 123 tornado fatalities already have been recorded—nearly double the annual average.
"The tornado death rate has bottomed out and is probably going to increase due to several factors," Ashley said. "Because of population growth and development patterns, including urban sprawl, tornado risk to the populace has increased in recent decades. Tornadoes are impacting larger populations that are more spread out, resulting in higher tornado death tallies."
The most dangerous window of time for a tornado, according to the study findings, is the period from midnight to sunrise. Tornadoes during this time period are 2.5 times as likely to kill as those occurring during the daytime hours.
People are more vulnerable during nighttime events because:
- Tornadoes are difficult for the public and trained spotters to see.
- People are more likely to be asleep.
- People are more likely to be in structures that are more susceptible to damage, such as single-family homes and mobile or manufactured homes as opposed to schools and large office or workplace buildings. (Nearly 61 percent of tornado fatalities in mobile homes take place at night.)
- Warning sirens are designed to mitigate hazards for people outdoors and are less effective at reaching those indoors.
"Because most people go to bed after the late evening news, they are sleeping and unaware of televised weather alerts," Ashley said. "And warning sirens give us a false sense of security. They're not designed for warning people who are already indoors. We're not seeing a forecasting problem but rather a communication breakdown. "Scientists, along with emergency managers and people living in tornado-prone areas, must work together to solve this problem," he added. "Right now, the best alert option during this overnight period is a weather radio."
A relatively small proportion of American households own weather radios, though they are widely available, cost as little as $25 and come equipped with alarms. As Ashley noted in previous studies, the nation's mid-South region is most vulnerable to nighttime tornadoes. In fact, while the "tornado alley" region of the Great Plains boasts the most frequent occurrence of tornadoes, most tornado fatalities occur in the mid-South region, which includes parts of Arkansas, Tennessee, Alabama and Mississippi.
Among the reasons for higher vulnerability: The southeast United States has the highest percentage of mobile-home stock compared with any other region east of the Continental Divide. The NIU meteorologist said 45 percent of all fatalities during tornadoes occur in mobile homes, compared to 26 percent in permanent houses.
The new study also finds that seasonal factors also come into play. The cool and spring-transition seasons from November to April have the highest nocturnal fatality rates, despite having relatively few tornado events. Daylight hours are at a minimum during these months. Also, storms that occur before the national peak in the severe storm season, which spans May and June, are more likely to catch people off guard.
"Nocturnal tornadoes are dangerous anywhere, but the danger is enhanced in the South," Ashley said. "There are more nocturnal events in the South than in the Great Plains. And the mobile-home density is much greater in the South as well. It's a combination of factors."WEATHER NOTE
New weather satellite moves toward launch
VANDENBERG AIR FORE BASE, Calif., Nov. 5 (UPI) --
The latest polar-orbiting environmental weather satellite developed by the U.S. space agency has arrived in California for its scheduled Feb. 4 launch.
The satellite, called NOAA-N Prime, was produced by the National Aeronautics and Space Administration for the National Oceanic and Atmospheric Administration. The satellite is similar to NOAA-N that was launched in May 2005.
The satellite will be launched from Vandenberg Air Force Base by a United Launch Alliance two-stage Delta II rocket.
NOAA-N Prime is the latest satellite in the Advanced Television Infrared Observational Satellites N series built by Lockheed Martin Space Systems Co., NASA said in a statement.
NOAA-N Prime will provide a polar-orbiting platform to support environmental monitoring instruments for imaging and measuring the earth's atmosphere, its surface and cloud cover, including earth radiation, atmospheric ozone, aerosol distribution, sea surface temperature, vertical temperature and water profiles in the troposphere and stratosphere.
Officials said the satellite will also assist the Search and Rescue Satellite-Aided Tracking system.
NOAA manages the polar-orbiting operational environmental weather satellite program, while NASA's Goddard Space Flight Center in Greenbelt, Md., manages the development and launch of NOAA satellites.MARITIME NOTE
Flares Banned over Safety Fears
|'Flares light up the nightsky for up to two minutes at a time - Photo by HEATHCLIFF O’MALLEY/AFP/Getty Images' .|
All 400 Coastguard rescue teams now have until the end of the year to use up their cache of flares or hand them over to the Ministry of Defence for disposal.
Volunteers have claimed the decision will put lives at risk because flares are essential for locating lost people and vessels in the dark.
One crewman said: 'This is the most stupid, ignorant thing I've heard of.
Flares light up the entire sky and aid rescue missions - something that obviously can't be done with a hand-held torch.
'This is over-zealous bosses bowing to health and safety nonsense - but they don't realise it could put people at risk.'
Tom Mullarkey, Chief Executive of the Royal Society for the Prevention of Accidents, also slammed the new ban. He called attempts by authorities to eliminate all element of danger from life as 'mindless', saying that the health and safety culture has 'gone too far'.
He insisted that individuals must retain the right to take risks so long as they do not injure others, and told safety experts that they will be accused of constructing a nanny state, adding that 'absolute safety' is an unattainable goal in any case.
A flare, also known as a fusee, can be shot into the air to heights of up to 700ft, illuminating vast areas of land or sea for up to two minutes at a time.
They have been used by the MCA since the First World War and deployed by Britain's 3,200 Coastguard volunteers in hundreds of rescue missions along the UK's 10,200 miles of coastline.
They require no legal licence to keep or fire, but the MCA - a government organisation which co-ordinates search and rescue missions - requires at least one volunteer in each crew to be certificated in their use.
But the MCA conducted a review earlier this year, which found no 'sound operational reason' for their continued use. It said 'operational pyrotechnics' were outdated and rarely deployed because of modern alternatives.
These include infra-red cameras, floodlights and night-vision goggles which are operated by the Coastguard's 12 helicopters across the UK. But there are fears among rescue teams who do not have immediate access to the helicopters and say torches do not match the illuminating power of flares.
Crews learned about the ban last week when the MCA contacted all 400 regional branches.
Last night an MCA spokesman told Daily Mail he was unaware of any incidents in which coastguard personnel had been injured using flares. But he added: 'We have suggested withdrawing the flares after a consultation with coastguard teams showed they are not being used. They are capable of causing considerable injury, and for that reason alone using safer alternatives is beneficial.'
However, another MCA Spokesman Mark Clark denied that the withdrawal was safety related. 'It's got damn all to do with health and safety,' he told Sail-World in an email, 'and all to do with the lack of use of pyros any more.
'We're reviewing the policy and if we see that there is a limited use of pyros in certain circumstances, then we'll change the guidance. There are generally one or two members of the team who are certificated to use these heavy duty and hefty pyros.'
The full text of the MCA's 'Operational Advice Note' can be read by clicking here
Flares will still be used by the RNLI and by the Coastguard's ten vessels which operate in conjunction with lifeboat crews.
Grounding of the Van Gogh
Independent investigation into the grounding of the Marshall Islands registered passenger ship Van Gogh at Devonport, Tasmania on 23 February 2008. ATSB REPORT
ATSB Transport Safety Report 252 on the independent investigation into the grounding of the Marshall Islands registered passenger ship Van Gogh at Devonport, Tasmania on 23 February 2008.