DN 2019_01 TDS
For Amendment 80 to ICAO Annex 3 (now scheduled for Nov 2023) the WAFS SIGWX forecasts will received a significant update. This includes the production of SIGWX data for multiple timesteps (from 6-hours to 48-hours at 3 hour intervals) and production in IWXXM format. This will be followed by the retirement of SIGWX forecasts in BUFR (Nov 2025) and the PNG format charts (Nov 2028).
There will be some subtle changes in the data that is included within the SIGWX and this is reflected in the IWXXM code that has been developed so far. At present we are working on the code, but are able to share a preliminary data set in order to get some feedback.
New SIGWX will include global coverage of all of the following:
- Jet Streams (no changes to the content/depiction of these)
- Turbulence areas – areas of MOD and SEV will be plotted, and due to the way the algorithm works should all be closed polygons. At present we are using the 1.25 degree WAFS CAT field to calculate this, but will be moving over to use the new 0.25deg Turbulence Severity data set that is being introduced in Nov 2020.
- CB areas – we will only be plotting areas of OCNL and FRQ CB (so no EMBD) and these should all be closed polygons. At present we are using the 1.25 degree WAFS CB field to calculate this, but are expecting to move over to use a 0.25 degree CB field.
The following are still to be developed:
- Tropopause height in contours (no more spot values), with the contours spaced 5000ft apart
- Icing areas – we will plot areas of MOD and SEV icing using the 0.25 degree WAFS Icing Severity field (that will be introduced in Nov 2020). It will have global coverage (Note: the existing BUFR field that combines icing and in-cloud turbulence will be split and in cloud turbulence will be discontinued)
- Markers to depict the locations of tropical cyclones, volcanic eruptions, radioactive release and dust/sand storms.
To allow early testing of the new format a test data set [Note 1] with sample plots (TestDataSet.zip) has been created covering jet streams, turbulence areas and CB areas. The data set will be renewed when more phenomena are introduced.
[Note 1: The fact that individual weather phenomenon has its own XML file in the data set is for testing convenience only. When in operation all phenomena involved in a SIGWX forecast shall be distributed in a single XML file]
The schemas can be found in the WxObjects branch of this GitHub repository. Those who are interested in the information model may want to visit this page. For comments and feedback please raise an issue here.