Once Super Typhoon Sanba’s outer bands brought heavy flooding rains to the Philippines before the storm headed northwards. It then struck Okinawa in nearly the same location that Typhoon Bolaven did only weeks ago, and then continued northwards and is now threatening South Korea.
Sanba underwent rapid intensification, strengthening from a category 1 equivalent typhoon to a category 5 in just over a day. In fact, Sanba became the strongest tropical cyclone anywhere on Earth this year with top sustained winds at 175mph and an estimated minimum central pressure of 900mb by the Japanese Meteorological Agency’s Tropical Cyclone Information department. Like many powerful storms, Sanba went through the infamous eyewall replacement cycle where outer bands organize into a concentric outer eyewall, this causes the inner eyewall to collapse and the storm is left weaker but with a larger wind field because the outer eyewall had a larger diameter. This new eyewall can then contract and allow the storm to strengthen, but then it risks going through another eyewall replacement cycle.
Typhoon Bolaven on the left and Typhoon Sanba on the right; centered over the same location in Okinawa. You can clearly see the size difference with Bolaven’s eye about 10miles wide and Sanba’s eye 35miles wide.
This was a fortunate turn of events as Sanba then struck Okinawa head on as a category three equivalent typhoon with 120mph winds. Pressures below 940mb were likely observed at Nago in between hourly observations of 947.1mb, 942.0mb, and 954.5mb at the height of the storm.
South Korea is now on alert for a strong Typhoon with winds near 105mph. Heavy rains are already falling – the Korean peninsula has seen severe flooding from the previous three tropical cyclones that hit the region earlier in the summer. Unfortunately, similar flooding is very likely as 3-9″ of rain are expected to fall, mainly in South Korea, as the cyclone passes.
Below is a table of peak wind gusts in the Okinawa area: