How Do We Get the Data?
All of the many types of data arrive at a River Forecast Center through a variety of ways. Here's a look at the different data distribution systems in use:
1. Cooperative Observers and ROSA
Every day at 7 AM local time, over 11,000 volunteer NWS cooperative observers report their daily data to the nearest Weather Forecast Office. These reports include the maximum and minimum temperatures, the rainfall, new snowfall, total snow depth and any other relavent weather that happened within the past 24 hours. The Weather Forecast Offices take all of the observer data from their area and distribute it to the rest of the NWS over AFOS, the Weather Service's computer system.
A new way of collecting observer data, ROSA, the Remote Observing System Automation system, was developed as a part of the ongoing modernization effort within the Wather Service. With ROSA, the observers call a central computer and enter their data with a touch tone phone. This data is then processed and distributed over AFOS.
2. GOES Satellites
The GOES, or Geostationary Operational Environmental Satellite, collects a wide range of data. The data most commonly associated with the GOES are cloud images, which aid meteorologists in weather forecasting. The GOES also collects data being transmitted from data collection platforms on the earth's surface. The data collected by the GOES includes river stages, precipitation, temperatures, wind reports, and other useful data. This data is then sent to a satellite receiving station in Wallops Island, Virginia, and then sent to NWS headquarters in Silver Spring, Maryland. After being processed at Silver Spring, the data is then distributed to the appropriate users.
3. CADAS System
CADAS, the Centralized Automatic Data Acquisition System, is pretty much what the name says. It is a computer system at Weather Service headquarters in Silver Spring, Maryland that retrieves data from precipitation gages and river gages over telephone lines. This data is processed and sent to the appropriate users.
4. The Telephone
If a forecaster wants a river stage and he wants it NOW, then he can call the gage over the telephone. Nearly all river gages can give stage data over the phone through either a series of tones or a synthesized voice. Those few gages that don't have any modern recording equipment will have a human observer assigned to the gage. So, the forecaster will just call the observer for the latest stage.
Last, the models and the forecasts.