Today we go up, up and away, to talk about balloons, specifically weather balloons. They are an indispensable tool used by weather forecasters. In winter, for example, when a forecaster is assessing whether sleet (those little BB-sized ice pellets, or freezing rain (the glaze of ice) will fall, they have to know the thickness of certain temperature layers aloft.
While we observe the surface pretty well, using human observers and automated sensors, it is only through the use of weather balloons that we can get values for the temperature, moisture, wind speed and direction in the sky above.
Weather balloons are launched from every National Weather Service forecast office across the U.S., twice daily, at midnight and at noon, Greenwich Mean Time. (This is the time on a line of longitude running through Greenwich, England.) The balloons are all released at these exact times, no matter what the local time is, so that as the balloons ascend simultaneously, upper-level weather maps can be constructed from the data transmitted back to all of the receivers.
The information transmitted by the balloons launched at the Caribou National Weather Service office is received by a receiver in the white dome you see on the property. Many people think that’s the Doppler radar site, but the Doppler is housed in a much larger dome, and is located in Hodgdon.
The information transmitted during a balloon’s flight is plotted on a diagram that a meteorologist then analyzes. These are very important forecast tools in all seasons, and a seasoned meteorologist knows how to read them well.
Another example of what can be found by weather balloons are higher velocity winds within the jet stream, called jet streaks. It is important for a forecaster to know where the jet streaks are. Just one of the things a jet streak can do is initiate significant thunderstorm outbreaks.
Once in a while, in advance of a potential severe weather outbreak for example, a special supplementary balloon is launched to even more closely monitor what is going on aloft.
By the way, weather balloons can ascend to more than three times the height of Mt. Everest before they burst. The instrument pack is attached to a little parachute, and roughly one-third of them are recovered and sent back to the the local NWS office for eventual reuse.
Ted Shapiro holds the Broadcast Seal of Approval from both the American Meteorological Society and the National Weather Association. An Alexandria, Va. native, he has been chief meteorologist at WAGM-TV since 2006. Email him at tshapiro@wagmtv.com.
