International Business Machines Corp. on Tuesday said the National Weather Service had purchased 900 IBM computers and 160 computer servers running the Linux operating system, increasing the speed at which it will be able to forecast flash floods, tornadoes and hurricanes. The computers, which are workstations, increase the speed at which the National Weather Service receives weather data over its previous computer systems from IBM competitor Hewlett-Packard Co., helping it to improve its forecasts, IBM said. The workstations will be rolled out to 168 sites and offices within the National Weather Service and the deal includes 160 of IBM's xSeries servers, IBM said. The contract is valued in the "multimillions of dollars," an IBM spokesman said, adding that in addition to the computer hardware, the deal includes some software and computer services. Refresh times for the weather service, which runs data-intensive applications, have been cut by four times to 62 seconds from 247 seconds, IBM said, speeding up data delivery and analysis. Previously, the weather service used HP's UX systems, which run HP's version of the Unix operating system on which Linux is based.