Four Typhoons at Once in the Western Pacific (Saudel, Narra, Gaenari)
As of the Japan Meteorological Agency bulletins issued on the morning of 23 August, there are four tropical cyclones running at the same time in the western Pacific. One typhoon, two tropical storms, and a depression that is expected to be named within the day.
This looks alarming written down, and it is worth being clear about what it does and does not mean. Four systems at once is not a record and not an anomaly for late August. What matters is that only one of the four is a serious storm, and the other three are in completely different places affecting completely different people.
Saudel is the one that matters this week
Typhoon Saudel, numbered 18 by JMA, was at 20.8N 143.1E at 06:00 JST on 23 August with a central pressure of 950 hPa and maximum sustained winds of 80 kt. That is a strong typhoon and the only one of the four with a properly formed core.
The forecast has it deepening tonight to 935 hPa and 90 kt, which moves it into the very strong grade, then reaching 925 hPa and 95 kt on the morning of 24 August. From there it tracks west-northwest: 24.6N 132.8E on 25 August, then 26.0N 128.7E on 26 August, which puts it essentially over Okinawa.
The newer part of the forecast is what happens after that. The extended track now carries it to 26.0N 125.4E on 27 August and 25.1N 122.5E on 28 August, weakening to 970 hPa and 65 kt. That last position is close to northern Taiwan. Five days out the error is large, but the direction of travel is no longer just past Okinawa and out to sea.
Narra is sitting still over the Gulf of Tonkin
Tropical Storm Narra, JMA number 19, was at 20.8N 107.7E with 994 hPa and 35 kt. That is inside the Gulf of Tonkin, between northern Vietnam and Hainan, and the striking thing about it is that it is barely moving.
The forecast keeps it at 994 hPa and 35 kt for the next three days while it drifts south, then back north, ending near 22.2N 108.4E on 27 August as it decays to a depression. A weak storm that stalls over a shallow gulf is a rainfall problem rather than a wind problem, and it is the kind of system that gets very little coverage while doing real damage inland.
The name is worth a footnote. Narra was submitted by the Philippines and is the name of their national tree. The western Pacific naming list is contributed by fourteen countries and territories in the region, which is why the names sound like they come from nowhere in particular.
Gaenari is already falling apart near Taiwan
Tropical Storm Gaenari, JMA number 20, was at 25.3N 122.6E with 998 hPa and 35 kt, which is just north of Taiwan. It is forecast to move west to 24.9N 120.0E by 24 August and then be downgraded to a tropical depression on 25 August.
So this one is on its way out rather than on its way in. Gaenari is a Korean submission to the naming list and means forsythia, the yellow flower that opens first in spring there. Names on this list are recycled every few years unless a storm is destructive enough to have its name retired.
There is a practical point buried in this. A storm being named tells you nothing about how dangerous it is. Gaenari and Saudel are both named systems this morning, and one of them has more than twice the wind speed of the other with a pressure 48 hPa lower.
A fourth system is still unnamed
The fourth is a tropical depression at 12.9N 134.5E with 1000 hPa and 30 kt, east of the Philippines. JMA forecasts it to reach tropical storm strength by this evening, which is when it would receive a name, then to weaken back to a depression by 25 August without ever becoming a typhoon.
Systems like this are the reason storm counts are argued about. Whether this one appears in the season total depends on whether it holds 35 kt long enough to be named, which is a difference of a few hours in a satellite estimate.
Why late August produces clusters like this
The western Pacific is the most active tropical cyclone basin on earth, and late August through September is the middle of its season. Sea surface temperatures are at their annual peak, the monsoon trough is at its most extended, and there is simply more ocean capable of supporting a storm than at any other time of year.
Four at once is not the same as four threats. Look at where they are: one near the Marianas heading for the Ryukyus, one stalled in the Gulf of Tonkin, one dying over the Taiwan Strait, one east of the Philippines going nowhere. The basin is roughly the width of the Atlantic and the Pacific combined at that latitude, and these systems are thousands of kilometres apart.
There is also a counting artefact at work. A basin this large will always have several disturbances in some stage of development during peak season, and how many of them get counted depends on where the naming threshold falls. Two of this morning's four are sitting exactly at 35 kt, which is the line between a depression and a named storm. Nudge the satellite estimate five knots either way and the headline becomes two storms or four.
The useful habit when a cluster like this appears in the headlines is to check three numbers for each storm rather than the count: central pressure, maximum sustained wind, and forecast position at day three. Everything else is framing.
Applied to this morning, that gives a short answer. Saudel at 950 hPa and 80 kt heading for Okinawa is the one to plan around. Narra at 994 hPa and stalled is a flooding risk for northern Vietnam and Hainan that will not make international news. Gaenari at 998 hPa and weakening is finished. The fourth has no name yet and probably will not need one for long.
The Japan Meteorological Agency publishes the position, grade and five day track for every active system in English here: https://www.jma.go.jp/en/typh/
Warnings and advisories for Japanese municipalities, including the Ryukyus, are published here: https://www.data.jma.go.jp/multi/index.html?lang=en
Satellite imagery on this page is from NASA Worldview and is in the public domain.
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