Weather Symbols

WMO STYLES & SYMBOLS

Professional meteorologists have traditionally plotted observations and produced forecast charts using a wide range of symbols, line styles and coloured areas, These have been internationally standardised for many years, and give true global interoperability, allowing the charts to be used irrespective of the user's language. The styles are defined in the publication: WMO No. 485: Manual on the Global Data Processing System, Part II, Appendix II.4, Graphical Representation of Data, Analyses and Forecasts. As well as English, it is available in French, Spanish and Russian.

SURFACE PLOTTING MODEL

A 'plotting model' describes the layout on a map of a collection of individual measurements associated with one location and one time. Many dozens of locations are plotted on a single map or map layer. The model is defined in the above Manual. See NOAA NWS AMS for some examples. There are over 400 symbols used. Google "Weather symbol images". The most common are here GIF 3259x2055 or PDF pages 18-20.

There is a similar, simpler model for upper air plotting defined in the same Manual.

GRAPHIC REPRESENTATION OF DATA ON WEATHER CHARTS

There are several groups of styles, and several examples of each have been collected:

Vector symbols:
Marker symbols, with a well-defined central location reference point:
Feature symbols, where the precise location reference point is not well defined: Line styles

Regions

AVIATION STYLES & SYMBOLS

Aeroplane pilots have used Significant Weather Charts using a wide range of symbols, line styles and areas, designed to be viewed in low-light environments, and robust to repeated imperfect copying. These have been internationally standardised for many years, and give true global interoperability, allowing the charts to be used irrespective of the user's language. The styles are defined in the publication ICAO Annex 3 Met Services for International Air Navigation, which is also available as: WMO No 49: Met Services for International Air Navigation, Appendix 1, APP1-16, Paras 1-4. As well as English, it is available in French, Spanish, Russian, Arabic and Chinese.

Feature symbols: Line styles
  • Fronts
  • Other lines
  • Jet Streams
Regions See ICAO symbols and line styles

Further Actions

At the Third Workshop on GIS/OGC Standards in Meteorology, Exeter, November 2010, we agreed to work towards publishing a definitive set of WMO symbols, probably on WikiMedia. IBL will make their symbol set available too.

When we have a reasonably good set, Envitia will try to put these in a portrayal registry, and then consider how to offer 'authoritative' references to well defined styles in SLDs, so that SLD rules can be provided, but alongside this have a 'But if you are a client good at drawing this then go ahead'.

Activity was kicked back into life by the first NASA Space Apps Challenge, May 2012, and by the Fourth Workshop on GIS/OGC Standards in Meteorology, Reading, March 2013, a complete set of both WMO and ICAO symbols and most line styles were made available in a public GitHub repository.

-- ChrisLittle - 08 May 2013
Topic revision: r10 - 22 May 2013, ChrisLittle
 

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