Two cyclones appear in the Western Pacific creating a weird interaction called the Fujiwhara effect
Currently, Typhoons Noru and Kulap are both spinning well to the east of Japan. The westernmost one is Noru, with Kulap about 800 miles to the east-northeast of Noru. Another Typhoon in the west Pacific, Sona or more correctly a tropical storm is expected to die out near China’s Hainan Island by Monday.
Noru is much more impressive looking than Kulap on satellite right now. In fact, one could argue Kulap has been absorbed into an upper-level low. Various numerical forecast models have suggested Noru and Kulap may, essentially, pinwheel around each other, something meteorologists call the Fujiwhara effect. The Fujiwhara effect details how two tropical cyclones 800 to 900 miles apart rotate counter-clockwise about one another.
Typically, the stronger storm will dominate the weaker, either fizzling it or merging with it altogether. In this case, Noru is expected to be the stronger “survivor” of this. This will stay in place for some time. Regardless, this long-lasting tropical cyclone will churn up impressive swells that may reach not just Japan’s east coast, but may also propagate farther south and west.