Current Weather Project
The aim of the project was to develop an XML data exchange format to (1) transfer a weather observation that would include automatic weather data from a PWS, plus manual and visual weather data, and (2) display the combined weather observation on a webpage using XSL transformation (XSLT). The display would also ideally include a coded SYNOP message and graphical representation of the weather data as a station weather plot.
Project Stages
The following stages were identified as key elements of the project:
- Match variables with the required station details, automatic weather data as well as manual and visual weather data,
- Create the template file and XML Schema Definition (XSD) document to specify the structure of the new Current Weather Document,
- Investigate the feasibility of creating a coded SYNOP message and a station weather plot from the automatic, manual and visual weather data,
- Create graphics to represent the automatic and manual weather data,
- Create a style document (XSL document) to specify how the XML data would be displayed in a web browser,
- Create education pages describing a Station Weather Plot, SYNOP Code Form and Weather Symbols and Code Figures.
Project Variables
The variables used in this project are listed below. Select a variable to view the complete XML element definition, including: the element name and description, the expected data type, the permitted values where explicitly defined, and whether the element is mandatory or optional.
The variables in the template file are replaced with the equivalent webtags provided by the PWS software. If a variable has no equivalent webtag, the variable is manually updated in the template file. If an optional variable subsequently becomes permanently unavailable, the syntax for that element in the template file is changed from <element>variable</element> to <element />.
- outside temperature
- station altitude
- windchill
- country
- international date
- wind direction degrees
- outside dewpoint
- evap sensor status
- 24hr evaporation
- wind gust
- high cloud type
- outside humidity
- station latitude
- station longitude
- low cloud type
- lowest cloud amount
- lowest cloud height
- maximum temperature
- middle cloud type
- minimum temperature
- relative pressure
- pressure change
- pressure trend
- station name
- past weather
- wind direction points
- pressure sensor status
- present weather
- program name
- 1hr rain
- 3hr rain
- 6hr rain
- 24hr rain
- rainfall period
- rain sensor status
- total cloud amount
- wind speed
- station identifier
- sun sensor status
- sunshine duration
- horizontal visibility
- temperature sensor status
- 24hr time
- utc offset
- pressure change period
- cloud amount units
- dewpoint units
- distance units
- evaporation units
- height units
- humidity units
- pressure units
- rainfall units
- sunshine duration units
- temperature units
- wind speed units
- software version
- visual observation time
- wind sensor status
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XML Schema Definition
View the XSD diagram for this project.
Weather Graphics
More than 500 graphics were created for the graphical representation of the weather data. This includes over 400 graphics to replicate the WMO weather symbols, including symbols for: total cloud cover, types of low cloud/middle cloud/high cloud, wind direction & wind speed both separately and combined, past weather, present weather and pressure trend, and about 100 graphics to show descriptive text corresponding to the WMO code figures for visibility and base of lowest cloud.
More information: weather symbols and code figures
Data Display
The combined weather observation can comprise a mix of raw values and WMO code figures. Some of the raw values are plotted as they are reported, whilst others must be coded for the purposes of plotting. All of the code figures, with the exception of visibility, are represented by the appropriate weather symbols in the station plot.
The evolution of the XSL document that specifies how the XML data are displayed in a web browser is described in the following table:
| Version | Changes |
|---|---|
| 1.0 | initial code used only the raw observed values of mean sea level pressure, amount of pressure change, rainfall and wind speed |
| 1.1 | added support for standalone graphics representing wind speed |
| 1.2 | added support for encoded values of mean sea level pressure, amount of pressure change and rainfall |
| 2.0 | introduced programming variables to support graphics representing the combined wind speed and direction in the station weather plot |
| 2.1 | increased use of programming variables to remove duplicated sections of code |
| 2.2 | added support for alternative units of wind speed and a wind speed conversion to knots |
| 2.3 | added a time conversion to UTC and enhancements to the display |
| 2.4 | added a configurable timeout to remove old visual observations from the display |
| 2.4.1 | minor fix to the UTC conversion |
| 2.5 | added AEST and AEDT time descriptors, and a SYNOP report |
| 2.6 | added support for amount of evaporation and duration of sunshine |
| 2.7 | added fire weather danger indices calculated by FWI Calc and a fire danger rating graphic |
| 3.0 | added support for 3 and 6 hour rainfall amounts and redesigned the layout of the weather data |
Project Status
See an example of a full automatic and visual weather observation with plain vanilla styling.
This 2020 project successfully achieved its aims. It is operational and is open for ongoing development. View our latest weather observation.
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