Cyclone tracks in Australia region July 2010-June 2011 (11 tropical cyclones in total)
Abstract
BOM's 2010-2011 tropical cyclone forecast: 20-22 cyclones forecast with a high level of confidence.
BOM Summary:
Above average tropical cyclone activity expected for the Australian region (98% chance!)
Season outcome: 11 actual cyclones.
We previously looked at the BOM's woeful 2011-2012 tropical cyclone forecast. ABC provided some coverage of the original forecast (
Here and
Here) but didn't think it newsworthy to cover the outcome of that forecast. Remember for the 2011-2012 cyclone season Australia's premier meteorological institute predicted an 80% chance that cyclones would exceed the long term average (12). The actual number of cyclones (8) was 33% below the long term average.
Missed it by that much!
Looking to see if previous forecasts were any better, we turned our attention to the 2010-2011 season. This covered the time interval July 2010 to June 2011.
Here was BOM's 2010-2011 forecast (alternate site
HERE)
Summary: Above average tropical cyclone activity expected for the Australian region
The outlook suggests that the coming tropical cyclone season is likely to have
- a higher than average number of tropical cyclones over the full Australian region,
- a higher than average number of tropical cyclones in the Western region,
- an average to above average number of tropical cyclones in the Northern region,
- a higher than average number of tropical cyclones in the Eastern region.
For the full Australian region, there is a high degree of confidence that the total number of tropical cyclones will be above average (see Table 1). The forecast values from the two models (20-22) are significantly higher than the long-term average value of 12.
Table 1 Forecast values for the 2010/11 Seasonal Outlook for Tropical Cyclones (TCs) for the four main tropical cyclone regions and the northwest WA sub-region (105°E to 130°E).
| Region | Chance of more TCs than average | Likely number of TCs (average number) | Confidence (LEPS skill1) |
|---|
| Australian region | 98% | 20-22 (12) | High (46%) |
|---|
| Western region | 93% | 11-12 (7) | High (31%) |
|---|
| Northern region | 67% | 5 (4) | Low (3%) |
|---|
| Eastern region | 87% | 6-7 (4) | Moderate (21%) |
|---|
| Northwest WA | 75% | 7-8 (6) | Low (7%) |
|---|
The likely number of tropical cyclones is indicative only. It is expected that the total number of tropical cyclones will be in the vicinity of the values listed, and not necessarily within the given range. The values are the most likely number of tropical cyclones forecast by two models.
Regional features
- The largest increase in tropical cyclone numbers is expected to occur in the Western region, where 11-12 tropical cyclones are forecast (4-5 more than the average value of 7 tropical cyclones).
- For the Northern region, an average to higher than average number of tropical cyclones is expected with 5 tropical cyclones being forecast (the average value is 4 tropical cyclones). However, as the statistical model used to produce this forecast has low skill in this region, this prediction should be used with some caution.
- The Eastern region is expected to experience a higher than average number of tropical cyclones, with about 6-7 tropical cyclones being forecast (the average value is 4 tropical cyclones).
- The outlook for tropical cyclones in the area from 105°E to 130°E, where tropical cyclones can impact upon coastal WA communities, shows a 75% chance of above average tropical cyclone numbers for the 2010/11 season. However, forecast confidence for this region is relatively low.
This outlook covers the period from July 2010 to June 2011. Most tropical cyclones in the Southern Hemisphere occur from November until April.
So how did they go?
The cyclone tracks for season 2010-2011 are overlain on BOM's regional map at the top of the page. These are derived from reports from the
Darwin Regional Specialised Meterological Centre (links to monthly reports below). It seems BOM did worse in 2010-2011. For the 2010-2011 cyclone season Australia's premier meteorological institute predicted a 98% chance that cyclones would exceed the long term average (12). The actual number of cyclones (11) was below the long term average.
Missed it by that much! Perhaps the media can exhibit a little more scepticism when the next forecast is made. We look forward to the following questions being posed when the next seasonal outlook is made:
So how did your last two seasonal forecasts go?
Links to monthly BOM reports.
October 2010 1 tropical cyclone in Australia region (5°S-40°S, 90°E-160°E) Anngrek
November 2010 0 tropical cyclone in Australia region (5°S-40°S, 90°E-160°E)
December 2010 2 tropical cyclone in Australia region (5°S-40°S, 90°E-160°E) Abele, Tasha
January 2011 5 tropical cyclone in Australia region (5°S-40°S, 90°E-160°E) Vince, Bianca, Yasi, Anthony, Zelia
February 2011 2 tropical cyclone in Australia region (5°S-40°S, 90°E-160°E) Carlos, Dianne
March 2011 0 tropical cyclone in Australia region (5°S-40°S, 90°E-160°E)
April 2011 1 tropical cyclone in Australia region (5°S-40°S, 90°E-160°E) Errol
