Twister sweeps in with deadly stealth

WITH a hurricane, at least, you usually have a little time - to tape the windows, bring the kennel in and get out of town. Tornadoes may be many thousand times smaller, but they are also infinitely more stealthy. The weather services try to get the warnings out, but pinpointing a twister is a difficult science, writes David Usborne in New York.

Ask the people of Spencer, South Dakota, who awoke on Saturday morning to find their town all but obliterated. A quarter-mile-wide tornado swept into the tiny community at 8.32 pm on Friday; although a warning was issued 13 minutes earlier, almost no one had learnt of it in time.

On nights like that, it is often only the noise that announces the approach of a tornado. Everyone who has heard that noise describes it the same way: a freight train coming. The Spencer tragedy left six residents dead and confirmed the 1998 tornado season as one of the deadliest in recent history. It brought the death toll since January from tornado strikes to 121, more than double the number killed in the whole of 1997 and 365 per cent greater than the 26 deaths recorded in 1996.

This year's death toll is certain to move past the 122 killed in the US in 1984. The worst year in recent memory, however, was 1974, which ended with 315 people killed by tornadoes, many of whom perished during a "super-outbreak" when 148 tornadoes touched down in 14 states in 24 hours.

Although El Nino has ben cited as a factor in this year's stormy season, it is unclear how much it has really been to blame. This is often the time of year when most tornadoes strike, driven by collisions between warm, moist air moving up from the South and cold, dry air invading the US from Canada.

Another feature of this year, has been the unusually wide spread of tornadic activity over the US. The storm system that struck Spencer, continued to spawn tornadoes in parts of New England not normally at risk, leaving 18 dead.