The track forecast error bounds shown on the TSR Storm Tracker represent the mean distance between forecast and actual tropical cyclone positions at all lead times over a number of previous years. These errors are calculated by each tropical cyclone forecasting centre (see the Data document for more about these centres) during the post tropical cyclone season assessment of their forecast performance. The errors represent the average performance of tropical cyclone track forecasts at given lead times in a particular region during previous years. As such they do not indicate a definitive bound on the actual future cyclone position and serve as an indication only.
The table below shows the error values (in nautical miles) used by the TSR Storm Tracker.
| Region | Mean Position Error for each Forecast Lead Time (nm) | Data Period | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 0 h | 12 hrs | 24 hrs | 36 hrs | 48 hrs | 72 hrs | 96 hrs | 120 hrs | ||
| North Atlantic | 7.7 | 24.1 | 36.9 | 49.6 | 65.1 | 96.3 | 133.2 | 171.6 | 2015-2019 |
| North East Pacific | 8 | 21.8 | 34 | 44.9 | 55.3 | 77.1 | 99.1 | 123.2 | 2015-2019 |
| North West Pacific | 24 | 34 | 46 | 61 | 78 | 117 | 165 | 223 | 2014-2018 |
| North Indian | 35 | 39 | 43 | 52 | 65 | 88 | 120 | 167 | 2014-2018 |
| Southern Hemisphere | 31 | 40 | 50 | 65 | 83 | 119 | 162 | 223 | 2014-2018 |
