Background on Weather Observations
In order to accurately make weather forecast, a forecaster needs information about the atmospheric conditions. Every hour, thousands of stations across the world record temperature, pressure, visibility, dew point, wind speed and direction and many other variables. Many of the stations are automated weather stations with instruments that record conditions electronically. There are also many stations in which a person measures the atmospheric variables by hand. They use the following instuments:
- Thermometer - Measures temperature or measures dew point temperature when the tip of the thermometer is moist
- Barometer - Measures pressure
- Aemometer - Measures wind speed and direction
Where are these observations taken? The European Centre for Medium-Range Weather Forecasts (ECMWF) plots the locations of the latest observations used to run their forecast model.
So, how do you put all this information from a single station in one place?
The station model!
Station Model Symbols, what do the mean?
What does this code mean? Most of the time these station models contain the following key variables:
- TT - Temperature (usually in F for surface observations
- TdTd - Dew Point Temperature or in C for upper air observations)
- PPP - Pressure
- pp - Pressure Tendancy
- N - Cloud Cover
- ff and dd - Wind Speed and Direction
- ww - Current Weather
- VV - Visibility How far you can see from the station, expressed in miles.
How are these variables represented? Click on the variable above for help on interpreting it.
A few examples:
Current Wisconsin Observation Source: NWS
Click on the image for a better quality view:
