Performance met expectations overall.
The Bureau issued 3198 flood watches and warnings, with a timeliness of 95 per cent, which was 2 per cent below the target of 97 per cent by 2022.
- 63 per cent of flood forecast lead times met service level specification targets, which is below the target of 70 per cent.
- 71 per cent of flood forecast peak height predictions met service level specification targets, which exceeded the target of 70 per cent.
The Bureau issued 225 tropical cyclone warnings, 728 tropical cyclone outlooks and 52 storm tide advices. Tropical cyclone forecasts were well forecast overall, with location and intensity performance comparable to recent seasons. The 48-hour track accuracy was 135 km, which is comparable to the five-year average of 127 km. However, 2020–21 featured a higher proportion of weak systems that are generally less predictable. Significant cyclones such as severe tropical cyclone Seroja were very well forecast and enabled effective responses from emergency services and the community. 90 per cent of Australian tsunami bulletins were issued within the target of under 30 minutes, with an average response time of 19.6 minutes from earthquake to tsunami bulletin issuance.
Seasonal climate outlooks achieved annual forecast skill results above that of climatology. The average weighted hit rate for aggregated seasonal forecast skill was 66 per cent for rainfall, maximum and minimum temperature, which exceeded the target of 55 per cent. The skill results were 64 per cent, 73 per cent and 61 per cent for rainfall, maximum and minimum temperature respectively.
94 per cent of marine gale warnings issued for capital city local waters met accuracy standards. Warnings for all 18 large wave events met target accuracy standards.
89.3 per cent of one-day maximum temperature forecasts were within 2 °C of the observed temperature, compared to 89.6 per cent in 2019–20.
There was a 2 per cent improvement in the Bureau’s forecast accuracy (averaged over five years) as defined by the WMO CBS exchanged scores for 2020–21.
There was 14 per cent reduction in forecast error for the Bureau’s numerical prediction (including for high-impact multi-hazard events) in 2020–21, using 2018-19 as a baseline, meeting the target of 5 per cent reduction by 2022.
The Bureau achieved full or partial temporal and spatial consistency in data for six out of nine systems in 2020–21. Plans are in place to achieve consistency for all systems (excluding BARRA-2 and extended outlooks) by 2022.
Lead time for the Bureau’s numerical predictions for rainfall improved by around six hours and tropical cyclone intensity by around six hours (at longer lead times) in 2020–21