In 2023, there were also instances where weather phenomena had a significant social impact. We look back at the three themes that Weather News selected from among them.
① High temperature Japan’s annual average temperature is also the highest ever
2023 was a year in which various records for high temperatures were broken. Japan’s annual average temperature deviation is +1.28℃ (provisional value as of December 27), which is much higher than the highest ever of +0.65℃ in 2020.
In addition to the progress of global warming, it appears to have been greatly affected by changes in the oceans, such as the transition from La Niña to El Niño. Looking at monthly temperatures, January was the only month that was lower than normal, while March, July, August, and September all set record high temperatures.
From top to bottom: Northern Japan, Eastern Japan, Western Japan, Okinawa/Amami, January on the far left, December on the far right.
The temperature in summer was particularly symbolic. Northern and eastern Japan experienced higher than average temperatures for three months from June to August, with little time for the heat to subside.The high temperatures that began in the second half of July were due to increased convective activity near the Philippines, and the overhang of the Pacific high pressure system became record strong, and in the first half of August, warm air continued as typhoons No. 6 and No. 7 moved northward. The main factors appear to be that the water flowed in and the Foehn phenomenon also occurred.
The three-month average temperature was the highest in recorded history at 85 locations, more than half of the 153 meteorological offices. Numerous heat records were set, including the highest number of extremely hot days and midsummer days in a year in central Tokyo.
②While the number of typhoons occurring is small, typhoons that did not make landfall caused damage.
The number of typhoons that will occur in 2023 will be just 17, which is the third lowest number since statistics began in 1951.
There have been particularly few cases since September, with the number being 5, the lowest in statistical history. One of the factors is thought to be that a low-pressure area called the monsoon trough that stretches from the South China Sea toward the Philippines is weaker than normal, resulting in less convective activity.
Of these, only one typhoon made landfall in Japan.
◆Typhoon No. 7 makes landfall
Typhoon No. 7, which occurred near Minamitorishima, intensified to a very strong force and passed through the Ogasawara Islands. It then changed course northward and landed in Wakayama Prefecture on August 15th. The moist air blowing toward the typhoon brought heavy rain to the Tokai, Kinki, and Chugoku regions, and a special heavy rain warning was temporarily issued for Tottori Prefecture. According to the Fire and Disaster Management Agency, no one died as a result of Typhoon No. 7, but nearly 1,000 houses were damaged.
There are also typhoons that did not make landfall that had a major impact.
◆Typhoon No. 2 Heavy rain at the beginning of the rainy season
Typhoon No. 2, which approached in June, passed near Okinawa and then moved east-northeast over the sea south of Honshu. The stagnant seasonal rain front became more active, causing heavy rain on the Pacific side of western and eastern Japan, and many homes were flooded, mainly in Wakayama, Aichi, Shizuoka, and Saitama prefectures.
◆Typhoon No. 13 Heavy rain in Kanto, far from the typhoon
Typhoon No. 13 in September moved northward off the coast of the Tokai Sea, but before it made landfall, it weakened and turned into a tropical cyclone. However, rain clouds developed far northeast of the center of the typhoon, and rain continued to fall for a long time, mainly in Chiba Prefecture, resulting in record-breaking heavy rainfall. In Mobara City, Chiba Prefecture, a 6-hour rainfall of 278.0 mm was observed, which exceeds the average monthly rainfall in September.
Due to a series of river flooding and landslides, the Isumi Railway, which runs through the Boso Peninsula, sustained major damage to its tracks, but it only resumed operation in December.
③ Light rain mainly in western Japan after autumn
The lack of typhoons since autumn has led to light rainfall mainly in western Japan. Due to the severe lingering summer heat, the autumn rain front is not as active as in previous years, resulting in less rainfall mainly in western Japan.
Precipitation during the autumn period from September to November was less than half of normal on the Pacific side of western Japan, setting new records for the lowest rainfall in Oita, Matsuyama, and other areas.
Water levels at dams in western Japan have dropped due to low rainfall, and water intake restrictions are still in place in some rivers. In addition, the water level of Lake Biwa in Shiga Prefecture has fallen, reaching -0.7m for the first time in 18 years since 2005.
The amount of snowmelt that normally increases at this time of year is not very promising, as there is little snow in the mountains of western Japan. The water level at noon on the 29th was -0.77m and continues to slowly drop, and it is expected that the establishment of a drought countermeasures headquarters will be considered as early as the new year.
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2023-12-30 04:30:00
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