Typhoon 14 ‘Pulasan’ Makes U-Turn, Expected to Bring Heavy Rain and Winds to Japan as It Transforms into Extratropical Low Pressure

2024/09/20 22:56 Weather News

Typhoon No. 14 (Pulasan) made landfall in China, then made a U-turn, and returned to the East China Sea by 9 PM on September 20 (Friday).

▼Typhoon No. 14 9 PM, September 20 (Friday)
　Center Position　　　East China Sea
　Size Class　　／／
　Intensity Class　　／／
　Movement　　　　　Northeast 15 km/h
　Central Pressure　　　998 hPa
　Maximum Wind Speed　　　18 m/s
　Maximum Gust Speed　　25 m/s

In the future, it is expected to change to the nature of a temperate low pressure while moving eastward, integrating with the autumn rain front. There is a risk of heavy rain during the three-day weekend in the Tohoku and Hokuriku regions, and due to expected development of the low pressure, care must be taken regarding strong winds and high waves.
» Latest typhoon information

Supply of Moist Air to the Autumn Rain Front – Risk of Heavy Rain

Typhoon No. 14 is expected to move from the East China Sea and Yellow Sea to the vicinity of the southern coast of the Korean Peninsula, transitioning into a temperate low pressure by the night of the 21st (Saturday). The term “transition to temperate low pressure” does not indicate that the strength will diminish, but rather that its structure will change, so caution is still needed. It is also expected that when this typhoon transforms into a temperate low pressure, its maximum wind speed will reach 23 m/s with a maximum gust of 35 m/s. Generally, when a typhoon turns into a temperate low pressure, the strong winds spread out over a wide area, not just limited to the vicinity of the center, thus making caution necessary in areas far from the center.

It is predicted that by the time it becomes a temperate low pressure, it will integrate with the autumn rain front. On the 22nd (Sunday), it is expected to move eastward in the Sea of Japan as a low pressure system along the front. The massive amount of moist air brought in by this low pressure, along with moist air flowing towards the front from the edge of the Pacific high-pressure system centered southeast of Japan, combined with the approach of a cold wave associated with an atmospheric trough from the north, is expected to create very unstable atmospheric conditions around the autumn rain front and the southern side of the front.

In Hokuriku and Tohoku regions, intermittent rain is expected to intensify, posing a risk of disasters such as landslides due to heavy rain, river swelling, and flooding in low-lying areas, requiring vigilance. Other areas from western Japan to eastern Japan are also likely to experience temporary heavy rain due to a front moving southward towards the end of the three-day weekend on the 23rd (Monday). Particularly, on the 22nd (Sunday), which is the autumn equinox day, there will be times when rain will intensify on the Pacific side, so please be cautious of road flooding, etc.

Probability of Entering the Typhoon’s Strong Wind Area

The forecast areas with a probability of entering the typhoon’s strong wind area of 3% or more within five days are as follows. (Japan Meteorological Agency)
　Amami Region　　　2 %
　Okinawa Main Island Region　13 %
　Miyako Island Region　　54 %
　Yaeyama Region　　72 %

New Typhoon Expected to Form

Typhoon No. 13 (Babinka) weakened and transformed into a tropical depression in central China at 9 AM on the 17th (Tuesday).

Meanwhile, the Japan Meteorological Agency announced information about a tropical depression in the South China Sea, stating, “It is expected to develop into a typhoon within 12 hours.” This tropical depression is predicted to move westward in the South China Sea, therefore it will not directly impact Japan.

▼Tropical Depression 9 AM, September 17 (Tuesday)
　Center Position　　　South China Sea
　Movement　　　　　West 35 km/h
　Central Pressure　　　998 hPa
　Maximum Wind Speed　　　15 m/s (near the center)
　Maximum Gust Speed　　23 m/s
» Radar Wind Mode (Wind Flow)
» Rain Cloud Radar

The typhoon is expected to accelerate further while moving northwest, passing near Okinawa Main Island at a speed of around 50 km/h tonight. Although it does not have a strong wind area, since the Okinawa Main Island and Amami are on the northern side of its path, caution is necessary for strong winds and high waves. Please also be aware of downpours of rain and sideways rain due to strong winds. After the evening, the peak of the rough weather is expected, so try to refrain from going out as much as possible and ensure safety indoors.

Reference: Numerical simulation results calculated by meteorological agencies from around the world

Each thin line in this figure represents the results of numerical simulations calculated by meteorological agencies from around the world. These results (members) are obtained through the process of ensemble forecasting, and are published to visualize the considerable range of possible paths.

Comparing these members shows that while there is a general tendency to move north of Japan, there is some variation in predictions for diverging towards northeastern directions or moving towards Honshu. If a westward path occurs, there could be impacts from wind and rain around the time of the three-day weekend, thus vigilance against changes in forecasts is necessary. As time passes, the error is expected to diminish, so please pay attention to upcoming information.

September is a Period with Many Approaching Typhoons

Number of Typhoons by Year
The occurrence of typhoons has been noted since Typhoon No. 13 formed on the 11th (Wednesday) of this month, and this is the fourth one so far this month.

Looking at the average number of typhoons, September averages 5.0 typhoons, making it the second busiest month after August. Meanwhile, the average number of approaching typhoons is 3.3, the same as in August, but the average number of landfall typhoons is 1.0 in September, making it the highest of the year.

This is the peak typhoon season, so please make sure to prepare for typhoon and heavy rain measures.
» Radar Satellite Cloud Image Mode

Typhoon Names

The names of typhoons occurring in the northwestern Pacific and South China Sea are pre-selected from a list of 140 names proposed by member countries of the international organization “Typhoon Committee,” and are assigned in the order they occur.

The name of Typhoon No. 14, “Pulasan,” is a name suggested by Malaysia, derived from the name of a fruit.
» Radar Typhoon Mode

Reference Materials