From VOA Learning English, this is the Technology Report.

　　Many Americans start to closely follow weather reports in the early fall. During the Atlantic hurricane season, predicting the strength and movement of these huge storm systems is of crucial importance. Thanks to new supercomputers, meteorologists for the National Oceanic and Atmospheric Administration (NOAA) are getting better at predicting the weather as far as six days out.

　　Hurricane Sandy hit the East Coast last October, and caused deaths and widespread damage, it was one of the costliest storm in U.S. history. At the time, some people blamed meteorologists for not correctly predicting the path of the storm.

　　But weather forecasting is extremely difficult, says Ben Kyger. He is the Director of Central Operations at NOAA's National Centers for Environmental Prediction in College Park, Maryland.

　　"You've got major patterns in the atmosphere, like the jet stream, but you've also got little eddies, little currents, little things happening all over the place. All these little changes are interacting with each other, continuously, all day long. So if you look at it from above, from a satellite, you see the atmosphere moving and churning in big ways and little ways."

　　Ben Kyger says oceans are another issue because they closely interact with the atmosphere and have a huge effect on storms. NOAA has spent about $20 million on two new supercomputers, in an effort to improve the dependability of the forecasts.

　　"These computers generate the initial model guidance that the whole forecast process depends on, for all the weather information that you see, with snowstorms, tornadoes, hurricanes, how hot it's going to be today — all of your weather forecasts start with what comes off of these supercomputers."

　　It takes a huge amount of computational power to examine data from weather satellites, ground stations and other sources. It then take a lot of power to predict temperature, air pressure, humidity and wind speed.

　　But human brains and experience are still very important to the process. Meteorologists at the National Centers for Environmental Prediction scan the same data that the supercomputers get before issuing a weather report.

　　"They are looking at lots of different models run of different computers, and then they are creating that five-day forecast. They use lots of scientific and subjective knowledge from doing it year after year. They know where the models are strong, where they're weak and they give us significantly better forecasts than the models would do by themselves."

　　NOAA issues worldwide forecasts every six hours every day of the year. The reports are free and are helpful for many countries that cannot afford their own weather service. NOAA continues working to improve its weather-forecasting abilities, another upgrade of its weather-predicting supercomputers is planed for as earlier as 2015.

　　And that's the Technology Report from VOA Learning English. I'm June Simms.