Yale Climate Connections

Even as South Korea endured the landfall of Typhoon Maysak on Wednesday night, September 2, a developing tropical storm in the Northwest Pacific posed the spectre of another potential typhoon – one perhaps even stronger than Maysak – threatening the nation by late this weekend.

Maysak reached the South Korea coast shortly after Thursday morning local time (around 1 p.m. EDT Wednesday). Landfall was just west of Busan, the nation’s second-largest city and the world’s fifth-largest port. Maysak’s broad wind field likely pushed a substantial storm surge into a wide swath of coastline, including Busan.

About four hours before landfall, the Joint Typhoon Warning Center pegged Maysak’s top winds at 105 mph, the equivalent of a strong Category 2 storm. Sustained winds by the time of landfall were likely lower than this value. At 1:01 a.m. local time Thursday, the sea-level pressure at a station on the south end of Geoje Island dipped to 952.5 mb, just above the all-time national record of 951.5 mb recorded in Busan during catastrophic Typhoon Sarah (1959), and just below the 954.0 mb recorded during Typhoon Maemi (2003). The Korea Meteorological Administration estimated Maysak’s lowest pressure at landfall at 950 mb.

Sarah and Maemi are two of just five typhoons on record to affect mainland South Korea as Category 2 or stronger equivalents. All but one of these struck the nation’s southeast coast near or west of Busan.

A livestock carrier was reported missing on Wednesday just west of Maysak’s track over the East China Sea, as noted by marinetraffic.com. A search for the Gulf Livestock 1 carrier was under way but hampered by weather. The carrier had a crew of 43 and some 5,800 livestock on board, according to Marine Insight.

Right on Maysak’s heels: Typhoon Haishen

Persistent steering currents from an upper low over northeast Asia may force the next Northwest Pacific system, Typhoon Haishen, to head toward South Korea. The rapidly intensifying Haishen is expected to reach Category 3 or 4 strength by Thursday as it heads northwest toward Japan’s Kyushu Islands.

Haishen will track farther east than Maysak for most of its life, thus avoiding the cold wake left by Maysak until this weekend, when models project it will be approaching the south coast of South Korea from the south-southeast. It’s too soon to be specific about landfall strength and location for Haishen, but intensity models are projecting that it may be even more powerful than Maysak as it passes over the Kyushu Islands.

Light to moderate wind shear of around 10 knots into Thursday should not pose much of an impediment to Haishen. Fueling Haishen’s strength will be a moist mid-level atmosphere, and sea surface temperatures along its track south of Japan at record or near-record levels (around 30°C or 86°F). Dozens of all-time heat records for September were set on Tuesday and Wednesday in Japan, which has just endured its third-hottest August on record, according to international weather records expert Maximiliano Herrera. Taiwan set its all-time September heat record on Wednesday – 39.4 degrees Celsius (102.9°F) at Donghe. It’s common for intense heat to develop in the sinking air just beyond the periphery of a strong hurricane or typhoon.

Tropical Storm Nana may reach Belize as a hurricane

Churning across the western Caribbean, Tropical Storm Nana was on track Wednesday to skirt past the north coast of Honduras before making landfall in Belize, perhaps not far from Belize City, on Thursday morning. A hurricane warning was in effect for Belize, as it’s possible (though not certain) that Nana will intensify to hurricane strength before it arrives.

Nana’s compact size and steady motion will help limit its impacts. The storm’s stronger right-hand (north) side will remain over water until Nana reaches Belize, thus sparing Honduras from the heaviest rains and high winds. Torrential rains will accompany Nana into Belize and spread into northern Guatemala and southern Mexico, with localized amounts of five to 10 inches capable of triggering flash floods and mudslides. Major storm surge is not expected, but water levels could reach three to five feet above astronomical tides near and just north of Nana’s center.

Short-lived Omar passing harmlessly through Northwest Atlantic

This year’s cavalcade of Atlantic systems was joined by Tropical Storm Omar on Tuesday, September 1. Omar is noteworthy as yet another record-setting early developer in this busy season (see below), but it won’t be a memorable storm in itself.

Heading into the open Atlantic well east of U.S. shores and northwest of Bermuda, Omar was clinging to life as a minimal tropical storm on Wednesday morning, with sustained winds of just 40 mph. Throughout its life, Omar’s showers and thunderstorms have been pushed far east of its center by strong upper-level winds. That process should lead to Omar’s demise in the next day or two, with only a remnant low persisting.

Omar’s arrival on September 1 marks the earliest date, in records going back to 1851, that any Atlantic season has produced its fifteenth tropical storm. This tops the record held jointly by Ophelia from September 7, 2005, and Nate from September 7, 2011. The earliest sixteenth named storm is Philippe from September 17, 2005. Only six more names remain on the 2020 Atlantic list before the National Hurricane Center will have to turn to the Greek alphabet, a last resort that’s been used only in 2005. That unforgettable year produced tropical storms Alpha, Beta, Gamma, Delta, Epsilon, and – on December 30 – Zeta.

Ocean heat as ‘fuel’ for hurricanes

The next system ripe for development is a large, loosely organized tropical wave now moving off the coast of West Africa. As it heads west, this wave will likely encompass a smaller system midway across the Atlantic. In its tropical weather outlook issued Wednesday afternoon, NHC gave this new system only a 10% chance of development by Friday, but a 60% chance by Monday.

With conditions overall still exceptionally favorable for development, it wouldn’t be a shock to see 2020 rivaling or exceeding 2005’s pace all the way to the Greek alphabet.

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Posted on September 2, 2020 (4:29pm EDT).