Super Typhoon Lekima scraped past Krosa, a concurrent typhoon, in the Western Pacific Ocean in August 2019. Lekima then went on to cause devastation in parts of China.
By HansPeter Roesli (Switzerland)
Starting as a tropical depression in the Philippine Sea (North Pacific Ocean) on 4 August, Lekima reached typhoon and super typhoon strength (tropical storm category 4) when passing between Taiwan and Okinawa on 8 August.
On the way to the Chinese mainland it weakened slightly to category 2 and made landfall just south of the Hangzhou Bay on 9/10 August. From there, following the coast northwards, it weakened to a tropical storm and then a depression. Its track ended on 11 August at 12:00 UTC where the coastline turns east.
The sequence of six-hourly images of band IR10.4 of Himawari-8, overlaid over the six-hour track points (Figure 2), shows the full life cycle of Lekima, from 4 August 00:00 UTC to 11 August 12:00 UTC. The numbers on the imagery indicate the typhoon category, from 1 (cyan) to 4 (red). The blue dots show the storm's positions prior to and after the typhoon phase.
Figure 2: Himawari-8 infrared animation, 4 Aug 00:00 UTC–11 Aug 12:00 UTC
Two other typhoons are visible in the animation — Franciso crossed south west Japan and dissolved over Korea on 7 August, and on 7 August Krosa entered the image sequence at the same latitude as Lekima, but further to the east.
The animation in Figure 3 shows the evolution of the Krosa-Lekima couple in the local day time on 8 August, side-by-side in True Colour RGB and false-coloured IR10.4 band from Himawari-8.
Figure 3: Himawari-8 True Colour RGB and infrared animation, 7 Aug 23:00 UTC–8 Aug 07:00 UTC
The closeness of the couple begged the question whether they would undergo the Fujiwhara effect, an example of the effect can be found in the case The Fujiwhara effect on extratropical cyclones. In fact, the distance at local noon (03:00 UTC) on 7 and 8 August was 1476 km and 1509 km, respectively (Figure 4), i.e. very close to the 1400 km point, below which interactions between tropical storms can occur. The movie does not show any sign of interaction; Super Typhoon Lekima just scraped past Krosa, with Krosa moving away untouched after the close encounter.
Super Typhoon Lekima in the West Pacific Ocean (CIMSS Blog)
Lekima – Northwestern Pacific Ocean (NASA Blog)
Typhoon Lekima Nears China (NASA Earth Observatory)
Lekima kills dozens and displaces millions in eastern China (AccuWeather)