The monster typhoon is seen switching from one form to the next as it continues to expel cold and hot air while creeping over the battered nation towards the Bering Sea.
The strange finding was shared on Twitter by Scott Cook.
Mr Cook said: “Typhoon Trami ECMWF 10 day forecast model for the West Pacific. 9/30 12 pm EST. Typhoon Trami has become subtropical over Japan as it moves NE. Then becomes extratropical as it moves quickly to the NE to the Bering Sea.”
The change in hot and cold air could be linked to the cyclone’s mounting pressure.
Extratropical cyclones are known for having cold air at their core and can occur over both land and ocean.
They derive their energy from the release of potential energy when cold and warm air masses interact.
Subtropical storms are cyclones that have hot air and can subsequently develop into a hurricane.
Examples of infamous subtropical storms are Gilda in 1973, Jose in 1981, Klaus in 1984, Allison in 2001, Lee in 2011, Humberto in 2013 and Tropical Storm Gaemi in 2018.
Trami barrelled towards the main island of Japan this afternoon and brought with it monsoon-like rain and winds of up to 136mph sparking power cuts and flight cancellations.
Trami has since been downgraded from Category 3 to 2 as it travels across Japan battering everything in sight.
Japanese media said the storm made landfall near the city of Tanabe.
State broadcaster NHK said residents had been advised to brace for “extremely strong winds and torrential rain”.
Kansai International Airport in Osaka, western Japan, which was heavily flooded by a typhoon last month, said it had closed its runways until Monday. The airport only fully reopened on September 21.
Airlines cancelled more than 1,100 flights, public broadcaster NHK said. And most of local trains and bullet trains in central and western areas suspended operations on Sunday, operators West Japan Railway and Central Japan Railway said.
Evacuation orders has been issued to 700,000 homes.