December 16, 2003
The National Weather Service (NWS) has 4 weather forecast centers in Montana. They're located near Billings, Missoula, Great Falls, and Glasgow. Every day at 4 a.m. and 4 p.m. Mountain Standard Time (1100 and 2300 UTC), weather balloons are released from the centers at Great Falls and Glasgow. At the same time that balloons are launched from these two Montana sites, balloons are also being released from about 900 other sites across the world (including 92 in USA).
A small box of sensors, called a radiosonde, is tethered to each balloon. As the balloon rises into the atmosphere, data is sent back to the weather center by radio signal. The sensors give meteorologists the temperature, pressure, and humidity of the air. More importantly, tracking the radiosonde by the radio signals it sends out provides information about wind speed and direction at higher altitudes. Data from the hundreds of balloons is collected to determine the location and speed of jet streams. Knowing what’s going on with jet streams helps the NWS forecast the movement of storms and predict other aspects of weather.