Super Typhoon Yutu re-intensifies to Category 5
After making landfall in the Northern Mariana Islands on 24 October, Super Typhoon Yutu underwent eyewall replacement cycles that brought about a drop to Category 4 intensity on 25 October. However, during the day on 26 October 2018 the storm again re-intensified to Category 5 (ADT | SATCON). Himawari-8 “Clean” Infrared Window (10.4 µm) images (above) showed a fascinating variety of storm-top features: (1) outward-propagating gravity waves, (2) a quasi-stationary (in a storm-relative sense, with respect to the moving storm center) curved “notch” — resembling a hydraulic jump — within the eastern semicircle, and (3) periodic bursts of warm/cold couplets (black/violet enhancement) — resembling “hot tower” impulses — located well northeast of the storm center (forming around 19-20º N/137º W) that propagated quickly northwestward. In addition, cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels embedded within darker purple shades) were seen southern eyewall during the 18-19 UTC period (1834 UTC image).A comparison of Himawari-8 “Red” Visible (0.64 µm) and Infrared Window images during the few hours after sunrise (below) showed an eye that was partially cloud-filled with low-level mesovortices.
An animation of Himawari-8 Visible images from 2302 UTC on 26 October to 0632 UTC on 27 October (below) provides a more detailed view of the mesovortices and some of the storm-top gravity waves. As was seen on Infrared imagery, a train of quasi-stationary concentric waves formed along the “notch” feature, becoming especially pronounced around 0532 UTC. A comparison of DMSP-17 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images from the CIMSS Tropical Cyclones site (below) showed Yutu around 2130 UTC.