The first phase of the new system, already in service, is being announced at ceremonies Friday. It's a cluster of 44 IBM servers with a peak speed of 7.3 trillion calculations per second.
By 2009 the system will be expanded to reach a potential speed of 100 trillion calculations per second, IBM said.
The added power is expected to help forecasters who run complex programs that take measurements of weather conditions around the world and project them forward in small increments in an effort to determine what the weather will be like in hours and days.
The results of the various outlooks form the basis for television and newspaper forecasts. They also are used in aviation, agriculture, disaster response and many other areas.
Improvements from the new computer power are expected to include better hurricane forecasts, with that storm season just getting under way.
This year the Weather Service will issue five-day hurricane forecasts, replacing the three-day advisories used since 1964.
Accurate, longer-range outlooks should help increasingly populated coastal areas. They also will be helpful for those who need more than three days to move themselves and their property, such as the Navy.
Instead of being located in a government facility, the new computer is at a specially prepared IBM facility in Gaithersburg, Md., and is linked to the Weather Service by high-speed data lines.
The deal is expected to cost about $200 million over nine years.
In 2000 the National Oceanic and Atmospheric Administration installed a supercomputer capable of 5 trillion calculations per second in its Forecast Systems Laboratory in Boulder, Colo. That lab studies forecasting and develops the computer models used in daily forecast work.
By Randolph E. Schmid