Typhoon Ampil Approaches: Heavy Rain and Strong Winds Expected as It Nears Kanto Region

2024/08/14 10:56 Weather News

As of 9 am on August 14 (Wednesday), Typhoon No. 7 (Ampil) is moving northeast over the sea southwest of Chichijima in the Ogasawara Islands.

It is expected to develop while moving northward and could come quite close to Kanto at its peak development during the second half of the Obon holiday. Please take preparations for heavy rainfall and strong winds seriously and early.

▼ Typhoon No. 7 August 14 (Wednesday) 9 am
Center Position: Approximately 230 km southwest of Chichijima
Size Class: ／／
Strength Class: ／／
Movement: Northeast at 10 km/h
Central Pressure: 975 hPa
Maximum Wind Speed: 30 m/s (near the center)
Maximum Gust Speed: 45 m/s
» Latest Typhoon Information

Ogasawara Islands to Experience Increasing Rain and Wind

Active rain clouds surrounding the typhoon have already begun to affect the Ogasawara Islands. On Haha Island, strong rain reached a maximum of 23.0 mm in one hour, and on Chichi Island, a maximum gust of 18.8 m/s was recorded. A storm warning and wave warning were issued at 10:09 am.

As the typhoon approaches, rain and wind are expected to intensify, with the possibility of active rain clouds on the eastern side of the typhoon affecting the area, necessitating caution due to heavy and severe rain.

The winds will also pick up, and rough seas are expected in the afternoons. Do not approach the sea. Furthermore, evacuating after strong rain and winds begin may be dangerous, so if you evacuate, do so early, and if not, stay in a room away from windows.

Kanto and Surrounding Areas May Experience Heavy Rain and Strong Winds Affecting Transportation

By 9 am on the 16th (Friday), the central pressure is expected to be 950 hPa with a maximum wind speed near the center reaching 40 m/s, making it likely to approach Kanto most closely at that strength.

There is still uncertainty in the possible track and speed; however, strong winds are anticipated from the Izu Islands to Kanto. If the typhoon’s path shifts westward, it could potentially see instantaneous wind speeds exceeding 50 m/s upon reaching land.

Additionally, due to the developed rain clouds and considerable moist air surrounding the typhoon, very heavy rain exceeding 50 mm per hour is expected, with a total rainfall exceeding 200 mm predicted over 24 hours.

Heavy rain and strong winds may impact transportation, particularly in Eastern Japan. Since this coincides with the end of the Obon holiday, there could be U-turns from return trips or travel-related movements. Check the latest typhoon information and traffic updates frequently, and adjust plans based on the weather.

After approaching Kanto, the typhoon is expected to change its path slightly eastward but may also affect northern areas such as Tohoku. Given the recent record heavy rain in Tohoku due to Typhoon No. 5, the region should remain vigilant.
» Radar Wind Mode (Wind Flow)
» Typhoon No. 7 Information

Possible Landfall Still Uncertain

Reference: Numerical simulation results of the projected path calculated by weather agencies from around the world.

Each thin line in this diagram represents the results of numerical simulations calculated by weather agencies worldwide. It is included to show the range of possible tracks obtained through the ensemble forecasting technique (members).

Comparing these members indicates that while there is general agreement in the tendency to move northward to the south of Kanto, there is a variability in predictions regarding whether it will impact land. The margin of error is expected to decrease as time goes on, so please pay attention to future information.

The Pacific High Pressure is Again Affecting the Typhoon’s Path

The Pacific High Pressure, which also greatly influenced Typhoon No. 5 that brought heavy rain to Tohoku on the 12th (Monday), is significantly affecting the path of Typhoon No. 7.

Typhoons primarily move due to upper-level winds, the most notable being the strong westerly jet streams; however, currently, they flow north of the Japanese archipelago, thus not contributing to the movement of Typhoon No. 7. This time, the typhoon is also expected to move north due to southerly winds blowing from the periphery of the high pressure.

The extent to which the Pacific High Pressure expands westwards has substantial implications on the typhoon’s path. If the high pressure spreads strongly to the west, the typhoon is expected to take a westerly course, whereas if the influence of the high pressure is less robust, the typhoon will take an easterly route.

Looking at the forecast cone, this typhoon has a range of paths that could either lead to landfall in Kanto and other areas of Eastern Japan or continue over the eastern sea without making landfall. A westerly track leading to landfall in Eastern Japan could result in heavy rainfall and severe storms, including areas of central Tokyo. Conversely, if it continues on an easterly course over the sea, the areas needing caution for heavy rain and strong winds would mainly be to the south and east, such as the Izu Islands and the Boso Peninsula in Chiba Prefecture.

Even a slight shift in the path east or west could significantly impact large cities such as Tokyo, so caution is necessary.

Reference: Numerical simulation results of the projected path calculated by weather agencies from around the world.

Each thin line in this diagram represents the results of numerical simulations calculated by weather agencies worldwide. It illustrates the considerable range of expected tracks obtained through the ensemble forecasting method.

Comparing these members reveals a general agreement in the northward trend towards the east of Japan, though there is variability in predictions diverging northeast or towards Honshu. If a westerly track occurs, it could result in wind and rain impacts around the time of a long holiday weekend, so careful monitoring for forecast changes is essential. As time passes, the margin of error is expected to reduce, so please pay close attention to future updates.

Probability of Entering the Typhoon’s Storm Zone

The probability of entering the typhoon’s storm zone (with probabilities over 5%) for the following prefectures by the fifth day is as follows (Meteorological Agency):
Aomori Prefecture: 7 %
Iwate Prefecture: 29 %
Miyagi Prefecture: 40 %
Akita Prefecture: 18 %
Yamagata Prefecture: 26 %
Fukushima Prefecture: 55 %
Ibaraki Prefecture: 72 %
Tochigi Prefecture: 49 %
Gunma Prefecture: 41 %
Saitama Prefecture: 55 %
Chiba Prefecture: 78 %
Tokyo Prefecture: 85 %
(Including Izu Islands and Ogasawara Islands)
Kanagawa Prefecture: 60 %
Niigata Prefecture: 18 %
Toyama Prefecture: 5 %
Yamanashi Prefecture: 39 %
Nagano Prefecture: 23 %
Gifu Prefecture: 9 %
Shizuoka Prefecture: 54 %
Aichi Prefecture: 14 %
Mie Prefecture: 5 %

Third Typhoon This Month

Typhoon No. 7 is the third typhoon to form this month, following Typhoon No. 6, which formed on August 11.

The average number of typhoons that typically occur in August is 5.7, making it the month with the most typhoons in the year. This year, several typhoons may emerge in the southern part of Japan as we enter the full-fledged typhoon season in the fall, so ensure you are prepared for typhoons and heavy rain.
» Radar Satellite Cloud Image Mode

Name of the Typhoon

The names of typhoons are preselected from a list of 140 names proposed by countries and organizations that are members of the international organization “Typhoon Committee.”

Typhoon No. 7’s name “Ampil” is a name proposed by Cambodia, derived from the name of a fruit from the legume family.
» Radar Typhoon Mode

Reference Materials