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West Pacific Super Typhoon Trami

By Scott Bachmeier •

Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play animation | MP4]

Himawari-8 “Clean” Infrared Window (10.4 µm) images (above) showed Typhoon Trami at Category 4 intensity during the 23-24 September 2018 period. The typhoon was going through an eyewall replacement cycle during this time — as seen on the MIMIC-TC product — which halted the period of rapid intensification that began early on 23 September (ADT | SATCON). Note the significant trochoidal motion (wobble) of the storm during the first half of the animation.

With the arrival of daylight late on 24 September UTC (25 September local time), the satellite presentation of then Category 5 Trami was quite striking, with surface mesovorticies within the large eye seen on both Visible and Infrared rapid-scan (2.5-minute interval) images (below). The deep-layer mean steering flow was also very light, allowing the forward motion of Trami to slow considerably.

Himawari-8

Himawari-8 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.4 µm, right) images [click to play animation | MP4]

Trami was in an environment characterized by low values of deep-layer wind shear, as shown in an animation of Himawari-8 Infrared Window (10.4 µm) images from the CIMSS Tropical Ctclones site (below).

Himawari-8 Infrared Window (10.4 µm) images, with deep-layer wind shear analysis at 00 UTC [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) images, with deep-layer wind shear analysis at 00 UTC [click to enlarge]

After nightfall on 25 September, and overpass of NOAA-20 provided VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images of Trami at 1634 UTC (below; courtesy of William Straka, CIMSS). Due to the very slow motion of the typhoon, strong winds had induced upwelling of cooler water from below the ocean surface — which in turn brought a gradual weakening of the storm to a Category 4 intensity. Ample illumination from a Full Moon demonstrated the “visible image at night” capability of the Day/Night Band.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]


Though the eye had become more cloud-filled, distinct surface mesovortices were still present — captured in stunning detail by an astronaut on the International Space Station:


Categories: Himawari-8, Microwave, NOAA-20, Satellite winds, Tropical cyclones, VIIRS