Skip Navigation 
NOAA logo - Click to go to the NOAA homepage National Weather Service Forecast Office   NWS logo - Click to go to the NWS homepage
National Weather Service Portland-Gray Maine

Upper-Air Program Virtual Tour
National Weather Service Forecast Office
Gray, Maine

Introduction Equipment Inflation Baseline Launch RRS Conclusion


This virtual tour will take you on a journey of what it takes to prepare and launch an upper-air atmospheric sounding, but first a little bit of background information and history. The National Weather Service weather forecast office (WFO) located in Gray, ME is a participant in the world-wide atmospheric sounding program. There are currently more than 800 radiosonde sites worldwide, with the United States/National Weather Service running or supporting 92 sites in North America and the Pacific region, and another 10 sites in the Caribbean.

The program allows for a time synched upper atmospheric "snapshot" across the entire globe as soundings are typically launched at a specified time. These worldwide soundings are then ingested into the various global and synoptic scale forecast models as a main source of information for the various forecast models to initialize off of and produce forecasts for meteorologists and various other users. These soundings are also used extensively as a real-time data source, as the information can be plotted on various thermodynamic diagrams such as Skew-T log-P Diagrams and Stuve Diagrams providing valuable information to meteorologists. Atmospheric soundings are also used extensively for air pollution models and climate research. For more information about the history of upper-air observations please click here: History of Upper-Air Observations. Click here for Historical Photo’s.

Map of CONUS Upper-Air Observing Stations

Map of CONUS Upper-Air Observing Stations

Skew T log-P Diagram with additional sounding data and calculations

SkewT log-P Diagram with additional sounding data and calculations

Courtesy: NOAA/NWS - Storm Prediction Center

Across the entire planet twice a day at midnight and noon Zulu time (Greenwich, England), weather balloons with radiosondes attached under them are launched to sample the global atmosphere. For NWS WFO Gray our weather balloons and radiosondes are launched at 7am and 7pm Eastern daylight savings time and at 6am and 6pm Eastern standard time. These flights are launched in all weather conditions ranging from blizzard conditions to high wind to temperatures over 100 degrees 365 days a year including weekends and holidays. The only real exception or delay of a flight would be when convective activity, like a thunderstorm, is present over or near the weather station. It is also important to note that "Special" soundings may be flown for various reasons which can include research, when rapidly changing conditions are present in the atmosphere, or when severe weather is expected in a region.

Next Page

Local Climate Water & Weather Topics:
Current Hazards, Current Conditions, Radar, Satellite, Forecasts, Climate, Weather Safety

National Weather Service
Gray Weather Forecast Office
P.O. Box 1208
Gray, ME 04039
Webmaster: GYX Webmaster
Page last modified: March 17th, 2009
Privacy Policy
About Us
Career Opportunities