Typhoon No. 20 is coming What is the reason for the big forecast circle?

Typhoon No. 20 occurs and heads north

Latest information on tropical cyclones and typhoons (Japan Meteorological Agency)

The low-pressure area near the island of Guam turned into a tropical cyclone at 9:00 pm on the 23rd (Sat) last night, and the Japan Meteorological Agency announced that this tropical cyclone is expected to turn into a typhoon within the next 24 hours. I'm here.

Aside from this tropical cyclone, there is no other tropical cyclone that has the potential to turn into a typhoon any time soon. It will be Typhoon No. 20 next to No.

Typhoon No. 20, which is expected to occur, will gradually develop and move northward, passing through the center of the forecast circle, crossing 20 degrees north latitude from the 27th (Wednesday) to the 28th (Thursday) and heading south of Japan. After reaching it, it is expected to turn northeast and approach Chichijima Island in the Ogasawara Islands with strong force on Friday, 29th, while increasing its speed.

The size of the forecast circle on the 29th (Friday) is 1,400 kilometers in diameter (700 kilometers in radius), and if it goes through the western course, it seems to come very close to Honshu. In fact, the reason why this forecast circle is so large is not due to the large fluctuation in the east-west direction, but rather due to the large fluctuation in the north-south direction. I don't think so.

What is the reason for the large forecast circle?

The above figure is an excerpt from the ensemble forecast for Japan. increase.

According to this, at 3:00 am on the 28th (Thursday), the latitude of 20 degrees north latitude will be exceeded, and although the calculations will vary, I have the impression that the center position is still managed somehow.

However, at 3:00 am on the 29th (Friday), the red circles were scattered widely in the north-south direction around Chichijima Island in the Ogasawara Islands. On the other hand, it is calculated that the slowest one has just crossed 20 degrees north latitude, and this difference has reached more than 1,500 kilometers.

This is the same trend even in other countries.In other words, the forecast circle of Typhoon No. It seems that this indicates that the blur is very large.

Because the westerly wind (strong wind zone in the sky) is already moving southward to the south of Japan, the fluctuation in the north-south direction is very large depending on whether you ride it early or late.

Conversely, although the possibility of approaching Honshu is rather small, it is highly probable that it will approach the Ogasawara Islands sooner or later.

The Ogasawara Islands need vigilance

The above figure is the computer calculation result when the current forecast circle is almost in the middle.

On the 29th (Friday), it is calculated that it will approach Chichijima of the Ogasawara Islands with strong force, and depending on the approach and force of the center, the maximum instantaneous wind speed may reach 50 meters or more.

In the Ogasawara Islands, it is necessary to pay close attention to the movement of Typhoon No. 20, which is expected to occur in the second half of next week.

At the moment, there is almost no calculation that it will approach Honshu, but it will never happen until the typhoon passes, so please keep an eye on future movements in Kanto and the Izu Islands.