Typhoon Haishen (2020)
Typhoon Haishen, known in the Philippines as Super Typhoon Kristine, was a powerful tropical cyclone that became the first super typhoon of the 2020 Pacific typhoon season. Haishen, which is also the season's tenth named storm and the fifth typhoon, originated from a disorganized low-pressure area situated near Guam. As the disturbance tracked southwestward and quickly organized, the Joint Typhoon Warning Center issued a Tropical Cyclone Formation Alert on the system, and a day later, on September 1, the system intensified into a tropical depression. Then, the Japan Meteorological Agency upgraded the system to a tropical storm, naming it Haishen as it moved southwestward. At about 12:00 UTC on September 2, the Philippine Atmospheric, Geological and Astronomical Services Administration indicated that Haishen had entered the Philippine Area of Responsibility and assigned the local name Kristine. Later that day, Haishen became a typhoon. On September 3, while drifting northwestward into extremely favorable conditions, Haishen underwent significant intensification, becoming a Category 3-equivalent typhoon and developing a pinhole eye before entering an eyewall replacement cycle. Strengthening resumed shortly afterward, and the JTWC estimated peak sustained winds at 155 mph as the storm reached Category 4 super typhoon status with a new, symmetrical, and clear eye.
Traversing northward toward land while gaining latitude, ocean heat content became unfavorable for supporting such a strong system, and while the central pressure decreased, the system's wind speeds began decreasing, as the structure began degrading. The eye's former shape was no longer present as it appeared ragged on satellite imagery, and Dvorak analysis indicated that Haishen was beginning to weaken steadily. On September 5, Haishen began to lose its eye as its inner eyewall began contracting, and it subsequently weakened to a category 3-equivalent typhoon. On September 6, Haishen made landfall on Japan and South Korea as a strong category 2-equivalent typhoon.
Haishen was the third typhoon within a span of two weeks to make landfall in the Korean Peninsula, the others being Bavi and [Typhoon Typhoon Maysak (2020)|Maysak (2020)|Maysak].
Meteorological history
On August 29, the JTWC began tracking a very disorganized tropical disturbance situated a couple hundred miles northeast of Guam. By the next day, the disturbance had quickly organized, and the JTWC issued a Tropical Cyclone Formation Alert for the low-pressure area. By the next day, it intensified into Tropical Depression 11W. Traversing generally south-westward, the depression quickly intensified into a tropical storm. The JMA soon followed and upgraded the system into a tropical storm as well, and was given the international name Haishen. Later that day, Haishen became a severe tropical storm as it headed southwest into the Philippine Sea. Intensification on September 3 was significant - with Typhoon Haishen acquiring a pinhole eye early in the day, but it later underwent an eyewall replacement cycle. The cycle completed quickly, however, and strengthening resumed almost immediately. Then, the JTWC noted the possibility of Haishen becoming a Category 5 super typhoon in one of their advisories.Entering the Philippine Area of Responsibility, the Philippine Atmospheric, Geological and Atmospheric Services Administration named the system Kristine. Early on September 4, the JTWC assessed that Haishen became a Category 4-equivalent super typhoon - with 1-minute sustained wind speeds of, with a clear, symmetrical eye visible on satellite imagery. On September 5, as Haishen's latitude increased, the ocean heat content in the area decreased, which disrupted the system's core and caused its eye to appear ragged on satellite imagery, subsequently indicating weakening, and dropping below super typhoon status.
Later that day, the system left the PAR and PAGASA issued its last bulletin on the typhoon. As the system continued its northward track toward the Japanese archipelago, it continued to weaken and became a category 3 typhoon as Haishen made another eyewall replacement cycle, and not too long after it dropped to a category 2 typhoon as it neared the Southern Ryukyu Islands of Japan. A mandatory evacuation order was issued for western Japan as millions of people evacuated accordingly. Haishen made landfall in Ulsan, South Korea at around 09:00 KST on September 7, with 10-minute maximum sustained winds at and the central pressure at. Shortly after, Haishen entered the Sea of Japan as a high-end tropical storm; due to the low-sea surface temperatures, Haishen quickly weakened and made landfall in the South Hamgyong Province, North Korea with 10-minute maximum sustained winds of and a central pressure of 980 hPa. Soon afterwards, JTWC issued its final warning on Haishen, as it moved further inland into North Korea. At 18:50 UTC, JMA issued its last advisory on Haishen, and declared it an extratropical low as it moved near the China–North Korea border.