A Road Weather Information System (RWIS) comprises automatic weather stations (AWS) (often technically referred to as Environmental Sensor Stations (ESS) as they also cover non-meteorological variables) in the field, a communication system for data transfer, and central systems to collect field data from numerous ESS. These stations measure real-time atmospheric parameters, pavement conditions, water level conditions, visibility, and sometimes other variables. Central RWIS hardware and software are used to process observations from ESS to develop nowcasts or forecasts, and to display or disseminate road weather information in a format that can be easily interpreted by a manager. RWIS data are used by road operators and maintainers to support decision making.US FHWA Road Weather Management FAQ
/ref> Real-time RWIS data is also used by Automated Warning Systems (AWS). The spatial and temporal resolution of a station network can be that of a mesonet or sometimes a constituent network in a network of station networks comprising a mesonet. The data is often considered proprietary although it is typically ingested into the major

numerical weather prediction Numerical weather prediction (NWP) uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions. Though first attempted in the 1920s, it was not until the advent of computer simulation in th ...

models.

Sensors

Thermometer A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermomete ...

for measuring

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on ...

and pavement conditions *

Anemometer In meteorology, an anemometer () is a device that measures wind speed and direction. It is a common instrument used in weather stations. The earliest known description of an anemometer was by Italian architect and author Leon Battista Alberti ...

for measuring wind speed * Wind vane for measuring wind direction *

Visibility The visibility is the measure of the distance at which an object or light can be clearly discerned. In meteorology it depends on the transparency of the surrounding air and as such, it is unchanging no matter the ambient light level or time of ...

sensor for detecting fog and smoke *

Rain gauge A rain gauge (also known as udometer, pluvia metior, pluviometer, ombrometer, and hyetometer) is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a predefined area, over a period ...

for measuring

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hai ...

* Surface sensor (embedded) for measuring road surface temperature and status temperature, dry or wet state, water depth, chemical concentration * Surface sensor (non-invasive) for measuring road surface temperature and status temperature, dry or wet state, water depth, chemical concentration,

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding (motion), sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative la ...

* Sub-surface probe for measuring below-grade temperature of roadway, surface temperature and resistance

References

Meteorological stations Intelligent transportation systems {{climate-stub