Typhoon Shanshan Strengthens: Japan Braces for Possible Impact as Storm Approaches

2024/08/25 22:30 Weather News

As of August 25 (Sunday) at 21:00, Typhoon No. 10 (Shanshan) is moving westward south of Japan.

▼Typhoon No. 10 August 25 (Sunday) 21:00
　Central position　　South of Japan
　Size category　　　／／
　Intensity category　　Strong
　Movement　　　　　Northwest 30 km/h
　Central pressure　　　980 hPa
　Maximum wind speed　　35 m/s (near the center)
　Maximum gust speed　　50 m/s
» Latest typhoon information

Peak Strength Expected to Develop to “Very Strong”

Since yesterday, Typhoon No. 10 has been unable to develop due to the influence of dry air; however, it is expected to begin developing again and become a “very strong” typhoon at its peak. Before making landfall in Japan, it is forecasted to return to a “strong” typhoon, but we must remain cautious.

Looking at the predicted course, Typhoon No. 10 is expected to move northwest due to the influence of a cold vortex up to around 29 degrees north latitude. It is increasingly likely to veer northeast from the south of Tanegashima and make landfall in western Japan around Wednesday, the 28th. After that, it is expected to progress northeast through the Sea of Japan, taking on characteristics of a temperate low-pressure system while heading toward northern Japan.

In areas close to the predicted path, there are concerns about the significant impacts of strong winds, with the possibility of powerful gusts of 40 to 50 m/s. There is a risk of blackouts and disruptions to logistics lasting for several days, so please prepare in advance. Additionally, even in regions distanced from the path on the east side, strong winds and severe weather may occur, warranting caution.

Moreover, in western Japan, particularly in Shikoku, there is a risk of considerable rainfall in areas where winds from the southeast collide with mountains. The total rainfall before the typhoon’s approach may exceed 300 mm, necessitating vigilance against river flooding and landslides.

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

Each thin line in this diagram represents the results of numerical simulations calculated by meteorological agencies worldwide. It is based on calculations of the center of the low pressure using ensemble forecasting methods, providing materials for examining the reliability of the forecasts by intentionally introducing errors into the initial values.

Upon comparison, although the tendency to veer toward western Japan is generally aligned, the regions of potential landfall range from Kyushu to the Kii Peninsula, highlighting the variability in affected areas and the degree of impact. Even minor differences in the path can lead to significant changes, necessitating close attention to forecast developments. As time passes, the margin of error is expected to decrease, so please stay alert for future information.

Probability of Entering the Typhoon’s Strong Wind Area

The following prefectural forecast areas have a 50% or higher probability of entering the typhoon’s strong wind area within five days. (Japan Meteorological Agency)
　Hyogo Prefecture　　　　　　　　52 %
　Tottori Prefecture　　　　　　　　52 %
　Shimane Prefecture　　　　　　　　52 %
　Okayama Prefecture　　　　　　　　58 %
　Hiroshima Prefecture　　　　　　　　60 %
　Yamaguchi Prefecture　　　　　　　　60 %
　Tokushima Prefecture　　　　　　　　56 %
　Kagawa Prefecture　　　　　　　　60 %
　Ehime Prefecture　　　　　　　　70 %
　Kochi Prefecture　　　　　　　　70 %
　Kumamoto Prefecture　　　　　　　　60 %
　Oita Prefecture　　　　　　　　67 %
　Miyazaki Prefecture　　　　　　　　75 %
　Kagoshima Prefecture
　　Satsuma and Osumi regions　　　76 %
　　Tanegashima and Yakushima regions　82 %
　Amami region　　　　　　　59 %

From the 27th (Tuesday) to the 29th (Thursday), there is a possibility of warnings for strong winds, high waves, storm surges, and heavy rainfall being issued. Disruptions to transportation are also expected to increase, with interruptions in railway operations and road closures likely.

Risk of Heavy Rain in Northern Japan Before Typhoon Approaches

In northern Japan, the activity of the front may increase, leading to the potential for heavy rainfall before the typhoon approaches. Extensive rain is forecasted to fall in Hokkaido and northern Tohoku, with localized heavy rainfall anticipated. In some areas on the Pacific side of Hokkaido, it is expected to exceed 100 mm, necessitating vigilance against river swelling and landslides.

Also, depending on the position of the front, there is a possibility of increased rain in Akita and Yamagata Prefectures, which suffered from flooding in July, so please pay attention to future information.
» Point weather forecast for the week

This is the sixth typhoon occurrence this month

This typhoon occurrence marks the third day since Typhoon No. 9 formed on the 19th of this week. It is the sixth typhoon to have formed this month.

Looking at the average number of typhoon occurrences, August typically sees an average of 5.7, making it the month with the highest frequency of typhoon formations. With six typhoons already formed this year, it appears to be on pace roughly on par with or exceeding the average.

As we transition from summer to autumn, we can expect an increase in typhoons approaching Honshu, marking the onset of the full typhoon season, and it is advised to prepare for typhoons and heavy rains.
» Radar satellite cloud image mode

Typhoon Name

The names for typhoons are culled from a list of 140 names proposed by member countries of the international organization “Typhoon Committee” and are assigned in the order of their occurrence.

The name of Typhoon No. 10, “Shanshan,” was suggested by Hong Kong and is derived from a girl’s name.
» Radar typhoon mode

Reference Materials and Others