Weather of Arabia - The year 2020 AD was marked by weather and extreme weather events, including the record-breaking Atlantic hurricane season, wildfires in Siberia, and winter storms in both Europe and the United States, and the year did not end before setting a new record for low pressure in the north The Pacific Ocean reached 921 mbar, as there was a strong subtropical storm (Extratropical storm) that struck Alaska on the last day of 2020, one day after Mongolia's high air pressure was set at 1094 mbar.
The North Pacific, Alaska and the Bering Sea set a new record for the lowest central pressure for a subtropical storm on December 31, 2020 AD, while it was crossing the center of the depression in the Aleutian Islands , the nearest meteorological station was recorded on Shemya island Alaska has an air pressure of 924.8 mbar, breaking the previous record of 926 mbar, which was recorded at Dutch Harbor on October 25, 1977, and when the system moved to the Bering Sea, a new minimum central pressure of 921 mbar was recorded. , This storm becomes the deepest storm ever in the Bering Sea, the last storm accompanied by severe pressure from the remains of typhoon Nuri .
The storm developed to this intensity at the time it was about to cross the Aleutian Islands, and this resulted from the combination of the extreme polar cold over Siberia, the warm equatorial air mass in the Pacific Ocean, in addition to the presence of a very strong jet current of 250 miles / hour between these two air masses .
There have been several severe subtropical cyclones at mid-latitudes recently, and there are indications of other storms on the way in the coming days, including a very severe subtropical storm near mainland Alaska and southeast Alaska next week.
The deep Arctic air that arose over Siberia met a tropical air mass that was transported from the warm western Pacific basin, where the sea surface temperature is around 30 degrees Celsius throughout the year, forming a severe temperature slope area between them, with a strong jet stream. Very separating the two air masses in the upper troposphere, where the velocity of the jet stream reached 110 m / s, at an air pressure of 200-300 mbar.
When the two masses meet, a merger occurred due to the geography of Central-East Asia, where the typhoon formed in a region of divergence at the highest level, and the interaction with the enhanced jet-flow line increased the depth of the depression, so the low pressure was formed near Japan on Tuesday and it was deepening steadily and rapidly until today Wednesday, with the acceleration of the drop in pressure, as the storm moved to the south of the Kamchatka Peninsula, where the pressure decreased by approximately 60 millibars per 24 hours and 75 millibars per 36 hours.
Then the system headed directly to the Aleutian Islands and the Bering Sea on the last day of the year, and on New Year's Eve 2021 AD, the system passed through the Aleutian Islands located in the far west of the country, accompanied by strong, destructive hurricane winds and high waves.
The factors that led to the formation of this storm and its development in this great way, was the extreme cold of the air spread across parts of Siberia and Russia, as the temperature reached less than -55 degrees Celsius, and this cold air mass was pushing east through Japan and the northwestern Pacific Ocean, dumping About a meter of snow crossed the main island in central Japan, and as this extremely cold polar air mass interacted with the powerful Pacific jet stream, the result was the explosive nature of the rapid intensification of the storm.
The sub-tropical storm brought a wide range of strong hurricane winds at speeds of more than 85 miles per hour to most of the waters west of Unalaska and the Pribilof Islands from Wednesday evening until Friday, and this monster storm also caused great heights of destructive waves of about 18 meters at The Pacific side of the Aleutians from Adak to Attu Island on Thursday.
The system took roughly the same path as the severe subtropical storm last weekend, which reached a low of 939 millibars on Sunday 27 December, and spread across the southwestern parts of the Aleutian Islands with extremely strong winds and intense waves of more than 16 meters.
It also set another air pressure record, which is a world record for the highest pressure at sea level, as the average sea level pressure for the Mongolian weather station Tsetsen-Uul rose to an unprecedented level of 1094.3 millibars, and thus this figure has been smashed. The previous record of 1089.4 mbar which was set on December 30, 2004 at the same station.
The extreme cold in Russia had another important effect. As usually happens when the air temperature is very low, the more dense cold air sinks and results in the surface pressure rising to very high values. This is what happened over Central Asia and pushed the atmospheric pressure values to an unprecedented value, Which was recorded in Mongolia in Central Asia, the weather station located in Tsetsen- Uul in western Mongolia recorded an average sea level pressure of 1094.3 mbar, with very low temperatures of -45.5 ° C. Checking these records, you will break the previous world record of 1089.4 mbar, which was also recorded in Mongolia, exactly 16 years ago.
But this value is still unofficial so far, as the World Meteorological Organization usually takes time to conduct a deep analysis of the environment, but it is also interesting to see that the surface temperature, which was around -45 ° C at Zetsen-Ull, at the time of recording The peak of surface pressure was close to those readings from the day the previous record was set (-44.8 ° C), which gives the 2020 readings a good possibility to confirm and officially acknowledge them.
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