Weather Forecast Office, New York, NY (WFO OKX) is one of the select
weather stations in the US that is part of the National
Weather Service Upper-air Observations Program. There are only 92 Radiosonde stations in North America and
the Pacific islands. Radiosondes provide
upper-air data that are essential for weather forecasts and research. WFO OKX uses a GPS-based
system called the Radiosonde Replacement System
(RRS), which has replaced the Microcomputer Automatic
Radio-theodolite (Micro-ART) system.
Weather balloons are launched from the upper air building which is
located in a valley adjacent to the forecast office (pictured, top row left). They are filled with
helium inside of the small building (pictured, top row center and right), then taken outside to
launch (pictured, bottom row center). The helium, which is a very light gas, allows the balloon to
reach heights of 60,000 feet above the earth's surface in about an hour. As the balloon rises,
the atmosphere thins and the pressure outside the balloon decreases allowing the balloon to expand
and eventually break. This usually happens within two hours of the launch at elevations of 80,000 to
An instrument, called a radiosonde, is tethered to the balloon
(pictured, bottom row center). As the balloon rises through the air, the radiosonde measures
temperature, relative humidity, and pressure. The radiosonde is equipped with Global Position System
(GPS) technology. The RRS tracking and receiving equipment, the Telemetry Receiving
System (TRS) and GPS, track and receive the radiosonde signals which contain the meteorological
data. As the position of the radiosonde signal is
tracked, wind data at various levels in the atmosphere is derived. The data is then sent to the
Signal Processesing System (SPS) for decoding and becomes ready for analysis.
After the balloon flight is complete, a technician ensures the data is
accurate before it is disseminated. Additional quality control checks are done at one of our
national centers before the data is incorporated into computer models which meteorologists use to
make their forecasts.
The balloons are launched from hundreds of locations around the world
twice a day every day of the year. The launches occur simultaneously worldwide!
This gives meteorologists a snapshot of the earth's three-dimensional atmospheric
Check out our most recent Upper Air Sounding Plot
from the 0000Z or 1200Z (8:00 p.m. or 8:00 a.m. EDT) Weather Balloon
But what happens to the radiosonde when the balloon breaks? The
radiosonde is protected by a styrofoam container, which cushions the radiosonde upon impact with the
ground. However, a small parachute will also pop out as the radiosonde falls, slowing its
Are the radiosondes returned? Frequently, the radiosondes are
discovered in a pasture, grove of trees, creek, peoples' backyards and other locations. A
self-addressed postage-paid envelope, which is in a compartment of the radiosonde container, can be
used to return the radiosonde to a reconditioning center for repair, and eventual reuse. Most of the
radiosondes launched from this office follow the prevailing wind and wind up dropping into the North
Atlantic Ocean, never to be recovered.