What does the typhoon forecast path" fan area" mean?
The typhoon future path on the Forecast diagram is spherical Expand, which is not typhoon enlarged, but rather the position uncertainty range.
Type of Typhoon size.
On the typhoon forecast chart, the future path is often painted as a gradually opening fan (internationally called the forecast cone). It represents the uncertainty of the Typhon Center’s future position, not the Typhon impact range, much less Typhon’s growing.
Each Forecast time effect has a "probability circle": Typhoon center has about 70% chance of falling within the circle.
How big is the forecast error?
Taking the CMA (China) average of recent years as an example, the Typhoon CenterForecast error difference was approximately:
| forecast time | Average error |
|---|---|
| 24h | About 60 to 70 km |
| 48h | About 100-120 km |
| 72h | About 150 to 200 km. |
| 120h | More than 300 km. |
That is to say, looking at the Forecast path after 5 days, the actual Landfall point may deviate several hundred kilometers—that’s why Typhoon was far away when countries forecast"fought", and gradually converged when it approached.
Use the Forecast path correctly
- Don’t just look at landfall.Typhoon effects range up to hundreds of kilometers, and both sides of the Landfall point will be affected, especially on the right side of the path (dangerous semicircle).
- Focus on trends rather than single forecastsForecast is updated every 6h, and forecast toward adjusts in the same direction several times in a row, indicating that the trend is established.
- Comparison of Multi-Organization ForecastTyphoonSays offers multi-agency Forecast path overlapping contrast, one look at the degree of the difference.
- Approaching with official early warning.Forecast within 24h is reliable and should be deployed strictly according to local government defense.