Typhoon Ampil Approaches Japan: Warnings for Severe Weather in the Kanto Region and Beyond

2024/08/13 17:09 Weather News

As of 15:00 on August 13 (Tuesday), Typhoon No. 7 (Ampil) is moving northeast at about 20 km/h south of Japan.

It is expected to develop further as it moves northward and may approach the Kanto region and other areas of eastern Japan with a storm zone during the second half of the Obon holiday. The extent of its impact will vary greatly depending on its path, so it is necessary to pay attention to its movements.

▼ Typhoon No. 7 August 13 (Tuesday) 15:00
　Position　　　South of Japan
　Size class　　／／
　Strength class　　／／
　Movement　　Northeast 20 km
　Central pressure　　990 hPa
　Maximum wind speed　　25 m/s (near the center)
　Maximum gust speed　　35 m/s
» Latest Typhoon Information

Beware of Severe Weather in the Ogasawara Islands Tomorrow

Typhoon No. 7 is progressing in areas with higher than average sea surface temperatures and is expected to develop further. Tomorrow, August 14 (Wednesday), it is expected to approach the Ogasawara Islands by night.

In the Ogasawara Islands, rain will intermittently fall, and as the typhoon approaches, rain and wind will strengthen. There is also a possibility of active rain clouds on the eastern side of the typhoon, so caution is needed for heavy rainfall and torrential rain.

The winds will also be fierce, and by the afternoon, rough seas are expected. Please do not go near the sea as it is dangerous. Furthermore, evacuating after the rain and wind intensify may be dangerous, so if you need to evacuate, do it early, and if not, stay in a room away from windows.

Possible Disruptions to Transportation in Kanto and Other Areas

After passing near the Ogasawara Islands, the typhoon is expected to strengthen and continue moving north, potentially approaching the Kanto region and other areas of eastern Japan with a storm zone from August 16 (Friday) to August 17 (Saturday), which is the end of the Obon period. It will then change slightly to a more easterly track, but it may still affect the Tohoku region and northern Japan.

There is still uncertainty regarding the possible paths and progression speeds; if it takes a westerly route, there could be significant rain and strong winds in Kanto. Moreover, the Tohoku region, which has already experienced record rainfall due to Typhoon No. 5, may again be affected.

Additionally, transportation in eastern and northern Japan may be impacted. As this coincides with the latter part of the Obon holiday, it overlaps with returning trips from homecoming and traveling. Please regularly check the latest typhoon and traffic information and plan accordingly based on the weather.
» Radar Wind Mode (Windflow)

Pacific High Pressure Influencing the Typhoon’s Path Again

Similar to Typhoon No. 5, which brought heavy rain to Tohoku on August 12 (Monday), the path of Typhoon No. 7 will be significantly influenced by the Pacific High Pressure.

Typhoons predominantly move due to upper-level winds. A typical example is the strong westerly winds, known as the jet stream; however, it is currently flowing north of the Japanese archipelago, and therefore does not influence the movement of Typhoon No. 7. This time as well, the typhoon is expected to move northward due to the southerly winds blowing along the edge of the high pressure.

The extent to which the Pacific High pressure expands westward will greatly affect its path. If the high pressure extends strongly westward, the typhoon will follow a westerly course; conversely, if the high pressure does not strengthen significantly, the typhoon will follow a more easterly course.

Looking at the forecast cone, this typhoon has a wide range of possibilities regarding whether it will make landfall in eastern Japan like Kanto or move over the seas to the east. If it takes a westerly path and makes landfall in eastern Japan, including central Tokyo, intense rain and heavy rain are likely. On the other hand, if it takes an easterly path over the seas, the areas that need to be cautious of heavy rain and strong winds will be limited to the southern and eastern sides such as the Izu Islands and the Boso Peninsula of Chiba Prefecture.

A slight shift in its path to the east or west could significantly change the impact on major cities like Tokyo, so caution is necessary.

Reference: Numerical simulation results of the paths calculated by meteorological agencies worldwide

The thin lines in this figure represent the numerical simulation results calculated by meteorological agencies worldwide. They are obtained through a method called ensemble forecasting (members) and are included to illustrate the substantial variation in possible paths.

Upon comparing these members, it is evident that while there is a general tendency for the typhoon to move northward off the east of Japan, there is considerable variation in predictions for subsequent movements either northeast or toward Honshu. If the path is more westerly, there is a possibility of adverse weather effects during the three consecutive holidays, so attention is needed for changes in the forecast. The error is expected to decrease as time passes, so please stay aware of future information.

Probability of Entering the Typhoon’s Storm Zone

The probability of entering the storm zone of the typhoon within the next five days for the following prefectural forecast regions is greater than 5%. (Japan Meteorological Agency)
　Aomori Prefecture　　　　　11 %
　Iwate Prefecture　　　　　30 %
　Miyagi Prefecture　　　　　37 %
　Akita Prefecture　　　　　20 %
　Yamagata Prefecture　　　　　27 %
　Fukushima Prefecture　　　　　50 %
　Ibaraki Prefecture　　　　　65 %
　Tochigi Prefecture　　　　　49 %
　Gunma Prefecture　　　　　45 %
　Saitama Prefecture　　　　　55 %
　Chiba Prefecture　　　　　70 %
　Tokyo Prefecture　　　　　68 %
　Kanagawa Prefecture　　　　58 %
　Niigata Prefecture　　　　　24 %
　Toyama Prefecture　　　　　12 %
　Ishikawa Prefecture　　　　　5 %
　Fukui Prefecture　　　　　6 %
　Yamanashi Prefecture　　　　45 %
　Nagano Prefecture　　　　　33 %
　Gifu Prefecture　　　　　19 %
　Shizuoka Prefecture　　　　　55 %
　Aichi Prefecture　　　　　23 %
　三重県　　　　　13 %
　滋賀県　　　　　6 %
　奈良県　　　　　5 %

This is the third typhoon to form this month

Average typhoon formation count

This is the third typhoon to form this month, following Typhoon No. 6, which formed on August 11.

The average number of typhoons forming in August is 5.7, making this the time of year when typhoons are most likely to form. This year, several typhoons may develop south of Japan. As we enter the full-fledged typhoon season leading into autumn, please prepare for typhoon countermeasures and precautions against heavy rain.
» Radar Satellite Cloud Image Mode

Typhoon Names

Typhoon names are pre-selected from 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. 7 “Ampil” was proposed by Cambodia and is derived from the name of a fruit from the legume family.
» Radar Typhoon Mode

Reference Materials etc.