In late February 2019 Typhoon Wutip became the strongest February typhoon on record in the Northwest Pacific basin.
By Jochen Kerkmann (EUMETSAT)
After forming as a topical depression 18 February, Wutip intensified into a tropical storm on 20 February, before intensifying into a typhoon later the next day.
On 23 February, while passing Guam, Typhoon Wutip became the strongest February typhoon on record in the Northwest Pacific basin, when it intensified further, reaching its initial peak intensity as a super typhoon with maximum 10-minute sustained winds of 185 km/h (115 mph), 1-minute sustained winds of 250 km/h (155 mph), and a minimum pressure of 925 hPa (mbar).
After weakening slightly, it resumed strengthening and early on 25 February reached peak intensity with maximum 10-minute sustained winds of 195 km/h (120 mph), 1-minute sustained winds of 260 km/h (160 mph), and a minimum central pressure of 915 hPa (mbar) (Figure 1).
Over the following days it weakened, before dissipating on 2 March.
Figure 2 shows a comparison of the Himawari-8 AHI Natural Colour RGB and the Cloud Phase RGB (slider of attached images, source: EUMeTrain ePort).
On the Natural Colour RGB, ice clouds are normally shown in cyan colour and water clouds in pink colours. However, this only works for water clouds with small droplets (large reflectivity in the NIR1.6 band). Water clouds with large droplets (low reflectivity in the NIR1.6 band) have a cyan colour, very similar to ice clouds, which makes the discrimination of water and ice clouds over the oceans (pristine air, cumulus and stratocumulus clouds with large droplets) very difficult.
As shown in this comparison, the distinction between water clouds and ice clouds is much easier in the Cloud Phase RGB that uses the new 2.3 micron band on the green beam, instead of the 0.8 micron band. In this RGB, ice clouds are shown in cyan (small ice) or blue colours (large ice), and water clouds are shown in magenta colours.
On the western side of the eyewall, small ice particles can be seen. This is confirmed when we look at the Convection RGB that shows the cold ice clouds with small ice particles, yellow in colour, see the comparison of the Convection RGB and the IR-VIS sandwich product (Figure 3).