Changes to specific aviation weather forecast formats are now in effect.
New versions of the low-level area forecast (ARFOR), AIRMETs and SIGMETs began being issued yesterday, 10 November 2016.
According to the Bureau of Meteorology, the changes were made to bring the forecasts in line with ICAO Annex 3 requirements.
Most significantly, ARFORs will no longer include weather above 10,000 feet, which will now need to come from the Medium and High Level Significant Weather Charts, Grid Point Wind and Temperature Charts, and NAIPS.
Other changes to AIRMET include a four-hour maximum validity period, no notification of winds increasing 20-40 kt at the lowest forecast level, and notification of isolated, occasional or frequent cumulo-nimbus (CB) and towering cumulus (TCU) cloud.
Changes to formats and coding have occured to make AIRMETs more like SIGMETs.
BOM has also made changes to the sequencing numbers for SIGMETs and removed the status (NEW, EXTD or CNL) from the remarks line.
Full information including documents on the changes can be downloaded from the BOM website.