In July, the Western Pacific kept strangely silent. No tropical storms formed over the ocean, making it the first time on record. As storms did not stir the ocean waters, the water temperatures rose, leading to unusual coral bleach near southwestern Japan.

Since August, the ocean suddenly has turned active, producing eight named storms one after another. Two battered the Korean Peninsula with historic intensities, and then the latest typhoon, Haishen, is on course to impact Japan as one of the strongest storms ever for the country.


Haishen’s Current Conditions

The disturbance got its name Haishen on September 1st, as it intensified to this year’s tenth tropical storm. Haishen means a “god of ocean” in Chinese. As of Friday morning, Japan time, the typhoon is packing sustained winds of 180kph (10min average) with a “very strong” status, which is the second highest on the typhoon scale.


Forecast Track

Forecast track (Courtesy: JMA)
Forecast track (Courtesy: JMA)

The Japan Meteorological Agency (JMA), which is responsible for the typhoon forecast internationally, predicts that Haishen’s central pressure could drop to 915hPa with sustained winds of 198 kph (10min average) by Saturday. This would categorize Haishen as “violent” status, which is the highest intensity on the afore-mentioned scale. The JMA forecasts it to drift over the southwestern islands into Sunday with the same intensity, getting very close to or even move over Kyushu from Sunday night to Monday morning as a “very strong” typhoon.


Possible Records in Japan

The southwestern islands including Amami and Okinawa could experience gusts of as high as 306kph on Sunday, which has been experienced only once in the country outside Mt. Fuji. On September 5th in 1966, Typhoon Cora hit Miyako Island, causing gusts of 307kph.

If Haishen makes landfall over Kyushu with a central pressure of 925hPa, Haishen could be remembered as the strongest typhoon to do so since record-keeping began in 1951. The most intense typhoon to hit Japan on record is Nancy, which pummeled Shikoku Island in 1961 with a pressure of 925hPa. Nancy caused extensive damaged, killed 202 people, and injured 5,000 others.

The top ten strongest typhoons for Japan listed below all formed before the year 2000. After 2000, the strongest is Jebi in 2018 with a pressure of 950hPa. Osaka, the third biggest city in Japan, experienced massive damage, and strong winds pushed a tanker into the bridge connecting Kansai International Airport to the mainland, leaving the airport closed for about three weeks.

Data source: JMA
Data source: JMA




Possible Records On the Korean Peninsula

Haishen could bring a couple of records for the Korean Peninsula as well. Haishen could approach South Korea into later Monday with a pressure of 940hPa. South Korea has never experienced a pressure below 950hPa since 1904, so Haishen might break the record. Also, with the landfall of Haishen, five named storms would have struck the Korean Peninsula in a year, which has never happened since 1951. The record so far is four storms in 2012 and 2019.


Back-to-back Record Typhoons

East Asia has been hit by back-to-back strong typhoons since the beginning of August. On August 26th, Typhoon Bavi made landfall in North Korea with a central pressure of 965hPa. This made Bavi the third typhoon to hit the nation in recorded history. On September 3, Typhoon Maysak struck South Korea. Tongyeong City recorded 952.5hPa, which is the second lowest pressure in recorded history, following the 951.5hPa brought by Typhoon Sarah in 1959.


Record Warm Water

Why are the historic typhoons forming so frequently? Once definite reason is the unprecedented high ocean temperatures. The surface temperatures of the Western Pacific have been about 2 degrees Celsius higher than normal this summer. According to a report released by the JMA last week, an area of ocean south of Japan had an average monthly temperature of 30 degrees Celsius in August, which was the highest recorded temperature in any month of year. This was due to a Pacific high-pressure system that extended further west, blanketing the waters with warm air. Moreover, zero typhoons in July left seawater unstirred and warm. The hot water can supply typhoons with abundance of water vapor, helping to develop the storms.


SSTs on September 3 (Graphic source: JMA)
SSTs on September 3 (Graphic source: JMA)

Prepare For Typhoons

Historically, September brings the strongest and most disastrous typhoons to Japan. With the favorable conditions for typhoon development, we might face challenging conditions. As the dangerous season has just started, we all need to get prepared.

When preparing for the typhoon season, there are some steps you might consider taking, including;

- Plan your evacuation route well ahead of time

- Create a family disaster plan

- Get emergency supplies such as water, food, and medicine

- Due to the fear of the Covid-19, include masks and hand sanitizer

- Get your house ready by cutting weak branches and trees and cleaning drains to avoid flooding

- Have a list of information source for weather such as theJMA, local government, NHK, or install weather apps


**ADDENDUM (9/7)**

Haishen didn’t make landfall in Kyushu, but it approached the island with a central pressure of 945-950 hPa. Haishen caused gusts of 214kph in Nagasaki Prefecture, and 595mm of rain in 48 hours in Miyazaki Prefecture.One woman was found dead in a gutter, four are missing and dozens of people were injured. 470,000 houses lost power at one point.