Super Typhoon Surigae

14 April 2021 12:00 UTC-21 April 00:00 UTC

Region

Pacific Ocean, Philippines, Japan, South China Sea

Satellites

Himawari-8

Instruments

AHI

Channels/Products

IR10.4, Airmass RGB, Tropical Airmass RGB, Sandwich Product, Water Vapour

Super Typhoon Surigae was the strongest ever early season typhoon in the North Pacific, when it formed in April 2021.

Last Updated

10 June 2022

Published on

21 April 2021

By Jochen Kerkmann (EUMETSAT), Ivan Smiljanic (CGI) and HansPeter Roesli (Switzerland)

In late April Typhoon Surigae, known in the Philippines as Typhoon Bising, was a powerful tropical cyclone east of the Philippines. It became the strongest Northern Hemisphere tropical cyclone to form before the month of May, and one of the most intense tropical cyclones on record.

Surigae became annular on 19 April, following an eyewall replacement cycle, which created a very large eye that could still be clearly seen in a variety of satellite imagery (Figures 1 and 2).

Figure 1: One day animation of Himawari-8 IR10.4 imagery, 10-min time step, 20 April

Surigae strengthened at a pace that was double the rate needed to qualify for rapid intensification (jumping by more than 160km/h in a day and a half), and its 190mph peak winds were stronger than Hurricane Dorian, which ravaged the Bahamas at the start of September 2019. The threshold for Category 5 status is 156mph.

Figure 2: Himawari-8 Airmass RGB, 14 April 12:00-20 April 15:00. Source ePort.

The Tropical Airmass RGB of 21 April (Figure 3) shows the extremely big eye (over 100km diameter), plus the presence of different airmasses at mid to high levels of the troposphere north and south of Surigae (the red v blue hues).

Himawari-8 Tropical Airmass, 21 April 2021 — Figure 3: Himawari-8 Tropical Airmass RGB, 21 April 00:00 UTC.

Figure 4 is zoomed in on different wave formations on top of the convective cloud bands surrounding Surigae’s eye. These wave formations are detected both in the visible and temperature signals of the AHI sensor. These are different types of gravity waves that are a consequence of very dynamic (vertical) processes associated to typhoon’s convection. Some of these waves are very untypical, like the quasi-stationary one stretching from the typhoon’s centre towards (roughly) Taiwan, annotated by the blue arrows in water vapour imagery (Figure 5).

Himawari-8 Sandwich product — Figure 4: Himawari-8 sandwich product (VIS0.6 channel overlaid with temperature information of IR10.4 channel) showing different wave formations around the typhoon’s eye.

Figure 5: One day animation of Himawari-8 WV6.2 imagery, 10-min time step, 20 April. Outflow cirrus clouds detected in the temperature field. Untypical quasi-stationary wave annotated by blue arrows.

Another sign of intense vertical motions are the radial cirrus bands that emerge from the system at the tropopause level. These are seen better in the looping water vapour (WV) imagery (Figure 5), appearing as outward facing linear structures, around the typhoon’s eye. These also appear far away from the Surigae’s eye, as red linear clouds over South China Sea.