Typhoon Trami has remained a powerful system over the open waters East of Taiwan and is now expected over the coming days to make a turn to the North and then North East where a direct impact over Japan appears likely. Above image via RAMMB / CIRA.

 

After Trami reached Super Typhoon, Category 5 strength several days ago… the system became near stationary / quasi-stationary over open waters East of Taiwan. Models were holding this potential for a number of days in the lead up and its come to fruition. Despite being in a favourable environment of warm sea surface temperatures of 28-30ºc, very low to low vertical wind shear of less than 10kts, and in some cases less than 5kts… the churning of the ocean caused by the system over the same areas has diminished ocean heat content (heat with depth) and this meant the system has undergone some obvious weakening characteristics including the eye becoming quite large and ragged. 

Current JTWC Forecast track map for Trami

 

While the system is no longer a super typhoon, this shouldn’t change the mindset of people. Trami is still expected to make a landfall over the Ryukyu Islands as a powerful system with winds gusting to around 195-200km/h. As the system gets a move on, its expected to briefly intensify to around 220km/h before making a landfall over Southern Japan across the weekend. On top of the damaging to destructive winds, widespread heavy to torrential rainfall is likely and this is expected to cause widespread flash flooding, river and creek flooding across the Ryukyu Islands and the majority of Japan where falls of 100-200mm are likely and isolated falls of 400mm+ are possible. A storm surge is also likely over the Ryukyu Islands and Southern Japan which is expected to cause coastal inundations. Power failures, land slides, mud slides, roads and highways being cut by both debris and flooding, along with some building damage is all expected across Japan, especially Southern and South East Coastal areas which will be impacted the hardest before the system weakens quickly due to mountain interaction, land interaction and increased vertical wind shear.

Rainfall forecast for the track of Trami. Red > 100mm, pink >250mm, white >400mm. Image via Windy