Why Do Different Meteorological Agencies Give Different Forecast Tracks and Intensities for the Same Typhoon?
TyphoonSays·防御问答 · Typhoon knowledge · 更新 at 2026-09-21
The “Showdown Between Forecasts”: The Scientific Truth Behind Forecast Differences
When you open a weather app and find that the CMA, the Japan Meteorological Agency, and the U.S. Joint Typhoon Warning Center have forecast different tracks and intensities for the same typhoon, there is no need for confusion or panic. These differences do not mean that one agency is right and the others are wrong. Rather, they reflect the nature of modern weather forecasting—a science based on probabilities rather than absolute predictions.
First, small differences in initial data can be amplified. Typhoons form over vast oceans, where there are far fewer weather observation stations than over land. The satellite imagery, buoy data, and radar observations obtained by different agencies vary in timing and accuracy. When these slightly different “initial conditions” are fed into supercomputers and processed through complex iterations of fluid dynamics equations, they can produce different results. This is similar to the butterfly effect: a small difference at the starting point can lead to a large discrepancy in the predicted position several days later.
Second, numerical forecasting models differ. Meteorological agencies use numerical weather prediction models developed by their own institutions, such as CMA-TYM in China, GFS in the United States, and ECMWF in Europe. These models differ in their understanding of atmospheric physical processes, parameterization schemes, and computational resolution. Some are better at capturing large-scale environmental steering flows, while others are more sensitive to changes in a typhoon’s internal structure. Therefore, a combined assessment of forecasts from multiple agencies often provides greater reference value than any single source.
Intensity or Track: Which Is Harder to Predict?
Compared with track forecasts, typhoon intensity is more difficult to predict, and forecast differences are often more pronounced. A typhoon’s track is mainly guided by large-scale environmental flows, such as the subtropical high, much like a leaf drifting along a current, whose behavior can be relatively well defined. Intensity changes, however, depend on sea-surface temperature, vertical wind shear, moisture transport, and the evolution of the typhoon’s inner-core structure.
Differences between models can become particularly significant when a typhoon undergoes complex processes such as “rapid intensification” or “eyewall replacement.” For example, one model may predict that the typhoon will weaken to a tropical storm before landfall, while another may expect it to remain at the severe typhoon level. According to the Chinese national standard Classification of Tropical Cyclones issued by the CMA, each increase in wind-force category results in a geometric increase in potential damage. Uncertainty in intensity therefore directly affects the level of disaster-prevention preparations required.
What Should Residents Do?
When faced with forecast differences, the public need not focus on specific distances in kilometers or numerical wind-speed values. Instead, they should pay attention to trends and the range of potential risks.
- Check ensemble forecasts: Many professional platforms provide “probability circles” or “ensemble forecasts” showing the range of areas a typhoon may pass through. If your location falls within this range, you should be ready to take precautions.
- Follow official warnings: Track forecasts are only a reference; the definitive guide for action is the warning signals issued by local meteorological authorities. The specific criteria for suspending classes, halting work, or suspending transport services vary by location, so follow the guidance issued by local governments.
- Adjust dynamically: A typhoon’s forecast track generally begins to converge during the 24–48 hours before landfall, when forecast accuracy improves substantially. Until then, stay informed while avoiding excessive anxiety.
The core principle of disaster preparedness is to “assume the warning is valid rather than dismiss it.” No matter how forecasts are adjusted, strengthening your own emergency supplies and awareness of evacuation options is the best way to cope with uncertainty. Real-time typhoon tracks can be checked at TyphoonSays (taifengshuo.com).
This article is original educational content from TyphoonSays. Please refer to the latest official announcements from local governments for policy standards.