今年第1号台风为何“姗姗来迟”?

Group 1 - The first typhoon of the year, "Butterfly," is expected to make landfall in the coastal area between Sanya and Dongfang on the morning of June 13, marking it as the first typhoon to land in China this year [1][2] - The average formation date for the first typhoon in the Northwest Pacific and South China Sea is March 25, but this year, "Butterfly" formed on June 11, indicating a significant delay [1][2] - Three main reasons for the late formation of the typhoon include lower than average sea temperatures in the South China Sea, a persistent strong subtropical high in the Western Pacific suppressing tropical convection, and abnormal activity of the tropical convergence zone and monsoon [1] Group 2 - The frequency of typhoons making landfall in Hainan Island in June has been increasing, with only one recorded from 1991 to 2012, compared to three from 2013 to 2020, averaging less than one every three years [2] - Typhoons that land in June are generally weaker, with an average intensity of strong tropical storm level, and the strongest recorded June typhoon reached typhoon level [2] - Since 1949, only one first typhoon, "Raccoon," made landfall in Hainan on April 18, 2008, making "Butterfly" potentially the second recorded first typhoon to land in Hainan Island [2]