Weather service's supercomputer burns.

A fire late last month destroyed the primary supercomputer used for predicting the nation's weather, potentially lowering the reliability of forecasts for several months.

On Sept. 27, a fire broke out within the power pack of the National Weather Service's Cray C90 supercomputer in Suitland, Md. Firefighters quickly put out the flames, but they mistakenly used a calcium carbonate extinguisher instead of the carbon dioxide canisters in the computer room.

It was the calcium carbonate powder, rather than the fire, that caused irreparable damage to the computer, says Louis W. Uccellini, director of the National Centers for Environmental Prediction (NCEP) in Camp Springs, Md., which oversees the supercomputer operations.

The Cray C90 ran the weather service's primary forecasting models, which predict weather from a few hours to 16 days ahead. It also ran the foremost U.S. hurricane model, as well as the national El Nino model looking several seasons ahead. As a backup, NCEP has relied on two smaller computers to run most of the models, sometimes less frequently and at a reduced resolution. Other nations and the U.S. Navy and Air Force are also providing some computer outputs for NCEP.

"We believe all critical operations are being supported and our folks are doing their jobs," says Uccellini. The current limitations, however, have made it more difficult for meteorologists because they have less computer guidance for making forecasts. "There's more uncertainty in some of the products we issue," says Uccellini.

Even before the fire, the weather service had planned on retiring the 1994-vintage Cray. This year, NCEP purchased an IBM supercomputer capable of a peak speed of 690 billion floating-point operations per second (gigaFLOPS). The Cray's peak was 15.3 gigaFLOPS.

NCEP will start using the IBM on Nov. 15, but it may be a month or more before the new computer can take over all the functions of the old one, says Uccellini.