What type of information is available
What type of
RWIS weather information is available?
Iowa's winter weather brings an average of 34 inches
of snow annually. The Iowa Department of Transportation's Maintenance Division
is responsible for snow and ice control on 10,500 miles of Interstate and
primary highways. When you consider all the lanes of multiple-lane highways,
that is the equivalent of 25,800 miles of single-lane highway. The RWIS network
of weather sensors provides the decision makers responsible for snow and ice
control and other maintenance activities at the Iowa Department of
Transportation with weather information specifically related to the roadway.
The first RWIS site was installed in the Des Moines area in 1989. The value of
weather information specifically targeted for surface transportation was quickly
discovered, and the system has grown to a network of 58 sites throughout the
state. There are three types of information the RWIS sites provide.
Surface Temperature is a
measurement of the actual temperature of the roadway or bridge surface.
The surface temperature governs what will
happen to a highway or bridge when precipitation occurs in the winter more than
These sensors literally provide the temperature
"where the rubber meets the road.
Subsurface Temperature is the
temperature approximately 18 inches below the roadway surface.
Atmospheric Weather Data is the
information normally thought of as weather information. Weather instruments
collect air temperature, relative humidity, wind speed, wind direction, and
What type of AWOS weather information is available?
Iowa has 113 public use airports. Of these, the 41
airports with AWOS towers fulfill approximately 270,000 aircraft landings and
takeoffs every year. An AWOS tower at the airport provides pilots with more
informed flight planning information, as well as for a safer descent to a lower
legal altitude for landing approaches.
Collection of AWOS weather information?
The AWOS data is Atmospheric Weather Data and includes temperature, dew point,
barometric pressure, wind speed, wind direction, wind speed, peak gusts,
altimeter setting, density altitude, visibility, and cloud height. The stations
operate 24 hours a day and the weather data is updated every minute.
How else can I get AWOS weather information?
A computer-synthesized voice broadcasts the weather data that can be received either by ground-to-air radio or by telephone.
The weather information can also be accessed through the computer network. The
computer network is a statewide network that uses dedicated phone lines to
connect all of the AWOSs to a host computer via personal computers located at
each AWOS site. The personal computer at each site can be used to access AWOS
weather information form all of the other AWOS sites that are in the network. It
is also programmed to access the Federal Aviation Administration's Direct Access
Terminal (DUAT) system to receive national weather information and file flight
The computer at an airport site may be called from any personal computer
to access weather observations. A communications program such as HyperTerminal®
for Microsoft Windows® or comparable program must be used to access the airport
computer. The computer must also have a Hayes-compatible modem with a
transmission rate between 1,200 and 56,000 bps (56k). The modem setting should
be 8 data bits, 1 stop bit and no parity. After successfully calling one of the
airport sites, the information on the computer screen will have instructions for
the viewer to follow to acquire the desired weather data. In addition to the 41
AWOS locations, 14 modems have been installed at 13 other airport sites as part
of the statewide AWOS computer network.