How Are Typhoon Tracks Forecasted? Why Do Forecasts Vary by Country?
TyphoonSays·防御问答 · Typhoon knowledge · 更新 at 2026-07-18
How Supercomputers "Calculate" Typhoon Tracks
Typhoon track forecasting is not based on guesswork but on complex numerical weather prediction models. In simple terms, meteorological agencies divide the global atmosphere into countless grids and collect massive amounts of data from satellites, radar, weather balloons, and ocean buoys, including pressure, temperature, humidity, and wind speed. This initial data is fed into supercomputers, which perform calculations using equations of fluid dynamics and thermodynamics.
As a typhoon is a massive weather system, its movement is guided by various environmental flows, such as the subtropical high, westerlies, and monsoon troughs. Computers simulate changes in these large-scale environmental fields to deduce the typhoon's potential future trajectory. This is akin to predicting the path of a leaf in a turbulent river; we need to know the water's speed, direction, and whether there are any surrounding vortices. With advancements in observation technology and data assimilation capabilities, the accuracy of modern typhoon track forecasts has improved significantly. However, at its core, it remains a probabilistic scientific prediction.
Why Forecasts Vary Across Countries
Many residents notice that typhoon track maps issued by the China Meteorological Administration (CMA), the Japan Meteorological Agency (JMA), and the Joint Typhoon Warning Center (JTWC) of the United States often do not perfectly overlap. This is primarily due to the following key factors:
- Different Initial Data: Agencies have varying access to observational data sources and densities. Especially over vast ocean areas where data gaps are common, different methods of filling these gaps lead to different starting points for calculations.
- Different Numerical Model Algorithms: Each country or region possesses its own independently developed or imported numerical prediction models (such as China's CMA-TYM, Europe's ECMWF, and the US's GFS). These models differ in their parameterization schemes for physical processes, grid resolution, and calculation methods, leading to deviations in interpreting the same environmental field.
- Different Correction Experiences: The output from numerical models is typically "raw data." Forecasters need to apply manual corrections based on historical experience and local climatic characteristics. Different agency teams have varying understandings of typhoon behaviors in specific sea areas, which also contributes to differences in the final published tracks.
Therefore, consulting track forecasts from multiple authoritative agencies and focusing on the "ensemble mean" trend is often more reliable than relying solely on a single source.
Viewing Forecast Uncertainty Scientifically
It is important to recognize that typhoon track forecasts have inherent uncertainty, and errors accumulate as the forecast lead time extends. Typically, forecasts within 24 hours are quite accurate, while forecasts for 72 hours or longer mainly reflect general movement trends and potential impact ranges.
As a typhoon approaches, various regions will activate corresponding emergency responses based on indicators such as wind force and rainfall. Regarding specific regulations on school suspensions, work stoppages, and transport halts, standards may vary by location; please refer to announcements from local governments. Residents should not focus solely on the precise location of the typhoon center but should pay close attention to wind and rain impact warnings issued by meteorological departments. Even if the typhoon center does not make direct landfall, its outer spiral rainbands and strong wind circles can still cause severe disasters. It is recommended that the public develop the habit of monitoring official warning information, check windows and doors in advance, stock up on supplies, and prepare for disaster prevention.
Real-time typhoon tracks can be queried at TyphoonSays (taifengshuo.com)
This article is typhoonsay's original copy content, and the local policy standards are based on the local government's latest release.