In the past month or so, Freddy, the "long-lived" cyclone of the southern Indian Ocean, has attracted a lot of attention - Freddy has wandered around the Indian Ocean and has experienced a long and wandering life. The World Meteorological Organization said the storm could become the longest tropical cyclone on record, following Hurricane John in 1994, which lasted 31 days in the Pacific. To this day, the circulation cloud system that weakened after Cyclone Freddy made landfall in Mozambique is still in Mozambique, and some forecasts suggest that it may strengthen again and continue to prolong this extremely rare and abnormal cyclone activity.
1. Unusual hurricanes west of Peru
In fact, this March, there was more than one abnormal weather event in the southern hemisphere, and even no less unusual than Cyclone Freddie, which had been active for more than a month - on March 11, 2023, due to heavy rainfall and flooding caused by Tropical Cyclone Yaku, seven regions of the country entered a state of emergency, and the national health system entered a state of red alert, according to a report by Peru's National Civil Protection. Extreme weather has caused extensive damage to homes, roads and arable land, leaving 592 districts of the country at risk and 34 ports temporarily closed until March 16.
Tropical Cyclone Yaku is a low-pressure system that develops in the southeast Pacific Ocean, and the name Yaku is given by Peru and means "water" in the Quechua language. Moving west along the equator, it reached its peak around March 7 and reached the northern coast of Peru on March 10.
The appearance of Tropical Cyclone Yaku brought rare torrential rains and floods to the coastal areas of Peru. Because the region is located on the western side of the Andes, it is one of the driest regions in the world under normal conditions under subtropical high-pressure downdrafts, offshore winds, and the cold Peruvian Cold Current, also known as the Humboldt Current. The Atacama Desert, for example, is located in the region. But when Tropical Cyclone Yaku approached, it carried a large amount of water vapor and formed a clear uplift with the mountains, resulting in strong convective precipitation. At the same time, "Yaku" also disrupted the normal circulation of sea and land winds and the distribution of cold currents, causing the sea temperature to rise by several degrees Celsius, and forming a land wind blowing inward along the coast, which together caused violent rainfall above normal in the coastal areas of Peru, triggering a series of secondary disasters.
According to the news released by the National Institute of Civil Defense under the Peruvian Ministry of Defense on March 11, local time, tropical cyclone "Yaku" has caused serious flooding in the northern coastal area of Peru and the capital Lima, 58 people have died, many houses have been flooded or collapsed, and the number of people affected has reached 23,000, and the Peruvian Ministry of Health once declared the national health system on red alert. In addition to Peru, the heavy rains brought by Yaku also affected Ecuador, also brought local floods, landslides and other disasters, and caused casualties in western Ecuador.
Tropical cyclones in the southeast Pacific are very rare
What is a tropical cyclone? Simply put, a tropical cyclone is a powerful rotating storm system that forms over low latitudes due to surface temperatures above 26.5 degrees Celsius. Depending on their maximum sustained wind speed, they have different names in different regions: typhoons in the northwest Pacific, hurricanes in the North and Northeast Pacific, cyclones in the northern Indian Ocean, and cyclones in the southern Indian and South Pacific Oceans.
Well, what about in the Southeast Pacific? Tropical cyclones almost never form here – in some areas of the world, tropical cyclones rarely occur: in the South Atlantic, for example, due to lower sea temperatures and strong vertical wind shear, only a few tropical cyclones have been found to form in the South Atlantic, the more famous being Cyclone Catarina that hit Brazil. For example, the Mediterranean, because the Mediterranean Sea is located in the temperate zone, and the summer in the region is relatively dry and has little precipitation (Mediterranean climate), and occasionally Mediterranean hurricanes form. In the southeast Pacific, due to dryness, low sea temperatures under the influence of the Peruvian cold current, and excessive vertical wind shear, no tropical cyclone has been detected before 2023.
Among the cyclone systems in the southeast Pacific, only subtropical storm Lexi in the 2017-2018 South Pacific tropical cyclone season is more famous - on May 4, 2018, a system identified as a subtropical cyclone formed east of 120 degrees west longitude, a cyclone system belonging to the southeast Pacific Ocean, just a few hundred miles off the coast of Chile, Australian researchers informally named the storm Lexi, and NOAA classified the cyclone system as a weak subtropical storm.
Third, El Niño is coming?
Peru is a country in South America, located on the coast of the southeast Pacific Ocean, with a diverse climate and different geographical areas such as coasts, plateaus and jungles. Peru's climate is influenced by two important marine phenomena, the Peruvian Cold Current, also known as the Humboldt Cold Current, is a cold current that flows from the Antarctic ice sheet to the equator, bringing a dry and cool climate to the Peruvian coast. Therefore, tropical cyclones here are a rare weather phenomenon that can be said to be "desert snow". But the system was formed in areas where there are no regional specialized meteorological centers, so it is not officially classified, and perhaps future meteorologists will refer to Yaku as a "hurricane", which is obviously a rather unusual weather event.
Then some netizens have to ask: Is the rare and abnormal tropical cyclone activity in the sky over the sea west of Peru a problem with the Peruvian cold current? Is it a precursor to El Niño? The Peruvian cold snap and El Niño are usually antagonistic to each other. When El Niño occurs, warm currents in the east-central equatorial waters counteract and push out cold currents, making the Peruvian coast humid and hot, and rainfall increased. This is a catastrophic change for Peru, as it can lead to serious damage to agriculture, fishing, water, transportation, etc. The strongest El Niño on record occurred in 1997-1998, when Peru experienced more than 10 times more than normal rainfall, leaving hundreds of thousands of people homeless and billions of dollars in economic damage.
So, at the beginning of 2023, is Peru facing the threat of a new round of El Niño? The answer may not be optimistic. According to the forecasts of meteorological agencies and experts in many countries, the risk of El Niño is increasing significantly in the second half of 2023 after the end of La Niña in the first half of the year. Put this into perspective, the recent unusual hurricanes near Peru may be only a fraction of the extreme weather of 2023.
#Weather##Cold Air##La Niña##El Niño##热带气旋弗雷迪 #