Station Weather Plot

station weather plotA station weather plot is a graphical representation of the weather conditions at a given time and location, either on land or at sea from a ship, platform, moored buoy or drifting buoy. It enables a large amount of automatically and manually observed data to be displayed in a very small space on a weather chart.

Weather charts are produced every day at regular intervals by national meteorological services, and comprise the station weather plots from many locations with a common observation time. The weather charts are then analysed by a meteorologist to determine the pressure pattern (e.g. the weather map shown on TV) and to look for trends in the plotted weather elements as one stage of preparing weather forecasts and warnings.

The data plotted on a weather chart can include raw observed values, encoded values, code figures and weather symbols.

Raw & Encoded Values

The raw values of air temperature, dew point, maximum temperature and minimum temperature are plotted to either one decimal place or rounded to the nearest whole degree. We choose to display these data to one decimal place as per ABOM practice.

The mean sea level pressure is coded in tenths of a hPa and plotted as three digits by omitting the thousands digit(s):

The amount of pressure change is coded in tenths of a hPa. An amount of less than 10.0 is plotted as two digits including a leading zero if necessary. An amount of 10.0 or more is plotted as three digits:

The rainfall is coded as three digits for plotting. An amount of less than 1.0 is coded in tenths of a mm and prefixed by 99. An amount of 1.0 or more is coded as the nearest whole number and prefixed by leading zeroes if necessary. Nil rainfall is not coded:

The wind gust is coded as the nearest whole number then prefixed by G for plotting:

Code Figures & Weather Symbols

These links redirect to information about WMO code figures, weather symbols and detailed descriptions.

amount of cloud | base of lowest cloud | low cloud | middle cloud | high cloud | visibility
rainfall period | pressure trend | wind direction | wind speed | past weather | present weather

Layout & Decode

station weather plot layout guide

The layout of our station weather plot is shown above. It differs from the standard WMO station weather plot in regards to the positioning of amount of lowest cloud and the base of lowest cloud, and also the inclusion of wind gust as implemented by some national meteorological services.

Our minimum temperature and maximum temperature are manually reported, and only plotted with observations timestamped between 09:00 to 11:59 and 18:00 to 20:59 respectively.

Elements are omitted from the station weather plot in the following circumstances:

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