News of heavy rain continues across the Korean Peninsula, while another name has filled search bars out at sea.
It is Typhoon No. 15 Chan-hom.
Forecasts indicated that the typhoon’s center was headed toward Japan, but it is too early to conclude that it has nothing to do with Korea simply because it is “Japan-bound.” In addition to the location of the center, it is necessary to consider the extent reached by its rain clouds and winds.
3-line summary
1. Typhoon No. 15 Chan-hom formed in early August and moved northward toward Japan.
2. The August 12 forecast showed a track approaching land about 180 km west of Tokyo.
3. A typhoon’s impact should be assessed not solely by whether it makes landfall, but by considering its track, intensity, and the extent of its rain clouds together.
What happened
Based on the Korea Meteorological Administration’s typhoon advisories and reporting at the time, Typhoon No. 15 Chan-hom formed on August 5 and moved in a west-northwest to northward direction. The forecast as of early August 12 included a scenario in which the typhoon’s center would approach land about 180 km west of Tokyo, Japan.
Typhoon names are used sequentially from a list submitted in advance by member countries. “Chan-hom” is also a name on that list. Being given a name means that a tropical depression has developed into a typhoon after exceeding a specified threshold for sustained winds at its center; it does not immediately mean that a particular area will suffer major damage.
The increase in searches can be seen as the result of overlapping demand to check vacation plans, flights, maritime transportation, and whether there could be indirect effects in Korea as reports covered its track moving closer to Japan.
A typhoon cannot be assessed by its center line alone
On typhoon maps in the news, the line connecting the centers is the most conspicuous feature. But the actual danger extends much more broadly to either side of that line.
Rain and wind can occur even far from a typhoon’s center. In particular, depending on the typhoon’s direction of movement, the position of surrounding high-pressure systems, and its interaction with the monsoon front or low-pressure systems, high waves or strong winds and rain can occur even if the Korean Peninsula is not on the direct landfall track.
Conversely, even when the center appears close, the pattern of impacts can differ if the typhoon weakens or its rain clouds are concentrated on one side. For that reason, it is more accurate to keep checking which waters it will pass through and when, and how its intensity and radius of strong winds change, rather than simply asking whether it is “coming to Korea” or “not coming to Korea.”
The forecast cone is not the size of the typhoon
The broad cone-shaped area commonly seen on typhoon forecast maps does not represent the typhoon’s actual size. It more closely represents the range of uncertainty in the projected track, which grows over time.
A typhoon’s track can shift slightly depending on the flow of surrounding winds. It is natural for uncertainty to grow for forecasts further into the future. Rather than treating the projected landfall point on a single map as definitive for a distant date, it is advisable to compare the center position, maximum wind speed, and projected track whenever the Korea Meteorological Administration updates its advisories.
What should people check in daily life?
When a typhoon approaches, it is practical to check regional advisories and transportation information separately.
- People planning to visit coasts or islands: Check high-wave advisories, passenger ferry cancellations, and guidance on swell waves first.
- Air travelers: Check wind conditions at both departure and arrival airports, as well as airline operating notices, in addition to the typhoon’s track.
- Residents in flood-prone areas: Prioritize heavy-rain advisories, river water levels, and local government evacuation guidance.
- Everyday travel: If strong rain and wind are expected, avoid places that can become dangerous quickly, such as riversides, underpasses, and coastal roads.
Typhoon information becomes more accurate over time. In particular, for decisions that affect schedules, such as departures or travel, it is better to rely on weather advisories and operating notices on the day of departure than on a single article from several days earlier.
Summary
Typhoon No. 15 Chan-hom drew attention as it moved north toward Japan. The key point of the forecast at the time was its “approach near Tokyo,” but weather and marine conditions on the Korean Peninsula cannot be assessed from the typhoon’s center line alone.
Typhoon news should be read through repeatedly updated official advisories rather than a single track image. Looking at the center position, intensity, radius of strong winds and storm-force winds, and regional advisories together can reduce both excessive anxiety and premature reassurance.
References
- Korea Meteorological Administration, Typhoon Advisory
- Korea Lecturer News, Report on the track of Typhoon No. 15 Chan-hom
- National Typhoon Center, Typhoon Information