What is the white dome used for?
Please click picture for a larger image
Over the past few weeks, several residents have asked us what the strange structure is behind the new National Weather Service Forecast Office building is, and most notably the new white dome on top.
The building serves several functions, and is built to withstand the winds and storm surge of category 5 hurricanes. First, it will house the new forecast office's electric generator at a safe elevation above most hurricane storm surge levels. The generator will help the National Weather Service staff continue operations during severe weather conditions, should commercial power fail. It also will enclose the facility's trash container, keeping it enclosed so that our future neighbors won't have to worry about bad smells or storms making loose trash blow...or float...off the property. There will also be storage space for large items that will keep larger items protected and out of view, keeping the property looking neat and orderly.
One important function of the National Weather Service Key West is to conduct weather balloon launches. Launched twice daily, and more often when the weather is rapidly changing (such as before severe thunderstorms and hurricanes), weather balloons are attached to small instrument packages to obtain a lot of information about temperature, humidity and winds above the ground. This data is input into computer forecast models, and is also used right away by our office to determine the potential for strong thunderstorms, cloud ceilings that affect local pilots, and numerous other weather phenomena. Without this information, computer models would not be very helpful about predicting future weather. The balloons will be launched from the tower-structure on the main weather office facility. After we relocate to this new facility, weather balloons will be launched from a tower attached the the main forecast office building. You can see the balloon launch tower in the picture above, behind and to the left of the dome building in the foreground (Please click here to see a larger image).
This is where the dome comes in! As the weather balloon instrument sends a weak radio signal to report its observed data, a receiver dish protected inside the dome at the National Weather Service Key West will track the balloon's position and report this data to a computer inside the forecast office. No signals will be transmitted from the dish; it will only "listen" to the incoming signals from the weather instruments attached to the balloon while the balloon is in flight, and track the balloon's position to obtain valuable wind data from the ground through about 17 miles into the atmosphere. The dish (see a picture of one here) will be roughly 6 feet across and will have to turn in any direction the weather balloon travels. Therefore, the dome is sufficiently large enough to allow the dish to turn safely and for our dedicated electronics technicians to perform maintenance.
While similar in appearance, the new dome at our future White Street location should not be confused with our National Weather Service Doppler Radar unit, which will remain in its current location on non-residential ground on U.S. Navy property, on Boca Chica Key. We will continue to operate and use the doppler radar's information remotely for the preparation of warnings for the safety of life and property in the Keys, just as we currently do from the Key West International Airport.
For additional information, feel free to contact us, your local National Weather Service Forecast Office in Key West, at 295-1316.