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arashitranslation
Attention to Typhoon→"Bomb Cyclone"
Notwithstanding that the typhoon has left
why did the weather become stormy?
On 30 October 2017, what brought strong wind to a wide range of area was
what we call “bomb cyclone”
it is said that attention to be paid to this period of time.
Typhoon No.22 which approached the Japanese Islands during weekends and
brought heavy rain to various places.
At 0:00AM of 30 October it was no longer typhoon
but turned to be extratropical cyclone.
At 3:00PM it headed north up to the northeast of Hokkaido.
When hearing typhoon “changed to extratropical cyclone”
there may be people who feel relieved
but this is not the case.
Typhoon is made of warm air.
Whereas the extratropical cyclone is that the warm air from the south and
the cold air from the north collide with each other.
The greater the temperature difference between this warm air and cold air the more it develops
and then it becomes the “bomb cyclone”
and brings strong wind to a wider area.
This time, the typhoon carried very warm air,
Moreover, in this period of time, the air from the north was cold
this bomb cyclone was more developed.
This is the weather map at 6:00PM of 29 October
which Typhoon No.22 was at the south of Tokai Region.
At that time the central atmospheric pressure was 975hPa.
This was the weather map at 3:00PM on 30 October
the central atmospheric pressure of the extratropical cyclone was 936hPa.
In 21 hours the atmospheric pressure decreased by 39hPa.
Generally the lower the central atmospheric pressure
because the isobars narrow and the wind becomes stronger
there are occasions that it become a greater threat than typhoon.
Damages caused by “bomb cyclone” occurred in the past.
This was the visual of April 2012.
The “bomb cyclone” which went up north along the Japan Sea coast
brought strong wind damages to various places, and the wording “bomb cyclone”
became widely known this year.
Besides, in October 2015 “bomb cyclone” made a rage.
In Hokkaido strong wind with the maximum instantaneous wind speed exceeding 30m was recorded.
Electric poles fell down, buildings collapsed from the foundations
there were such damages.
It is not to be relieved even the typhoon is changed to be the extratropical cyclone.
Please continuously pay attention to the weather information.
Source: News Zeroイチメン (http://www.ntv.co.jp/zero/ichimen/2017/10/post-350.html)