"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," he said.

While the computational power needed to analyze data from weather satellites, ground stations and other sources is enormous, human brainpower and experience remains crucial to accurately predicting temperature, air pressure, humidity and wind speed.

According to Kyger, meteorologists at the National Centers for Environmental Prediction scan the same data the supercomputers get before issuing a forecast.

"They look at lots of different models, assess that and create the five-day forecast," he said. "They have a lot 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 each day of the year. Access is free — a benefit to countries that cannot afford their own weather service. NOAA has planned upgrades for its weather-predicting supercomputers set for 2015.