Japan, including Tokyo and the site of Saturday's deadly volcanic eruption, remains in the path of powerful Typhoon Phanfone.
Phanfone rapidly intensified on Thursday, local time, with its strength increasing from that of a Category 1 hurricane to a Category 4 hurricane in 12 hours.
The typhoon will remain in an environment conducive for further strengthening through the first part of the weekend, making it highly likely for Phanfone to approach or reach super typhoon status (maximum sustained winds of at least 240 kph or 150 mph).
Such strengthening may occur as Phanfone continues to track to the northwest before taking a turn to the northeast and threatening mainland Japan.
Phanfone is expected to take that turn prior to reaching the Ryukyu Islands. However, the powerful typhoon will still pass close enough to graze the islands from Amami northward with some rain and wind Saturday night through Sunday.
The island of Osumi and the nearby southeastern coast of Kyushu are at risk for damaging wind gusts of 130 and 160 kph (80 and 100 mph).
While some rain will arrive on Saturday night and Sunday morning across Shikoku and southern Honshu, conditions will deteriorate later Sunday through Monday in a west-to-east fashion as Phanfone heads to the northeast. Heavy rain will also eventually spread to northern Honshu on Monday.
The current projected path of Phanfone takes the typhoon over far southeastern Honshu late Sunday night or Monday. However, residents of mainland Japan still face dangers even if its center remains just offshore.
The most widespread impact from Phanfone will be flooding rain. Based on the forecast track of Phanfone, a general 100 to 200 millimeters (4 to 8 inches) of rain will inundate eastern Shikoku, as well as south-central and southeastern Honshu. This includes Hamamatsu, Shizuoka and Tokyo.
The worst of the storm will batter Tokyo Sunday night through Monday, when sustained winds of 65 to 95 kph (40 to 60 mph) will howl with higher wind gusts. Residents should prepare for widespread street flooding, tree damage, power outages and flight cancelations.
"There will even be 300 millimeters (a foot) or more of rain in the mountains," stated AccuWeather.com Meteorologist Adam Douty. That amount of rain is sure to cause not only flooding but also mudslides.
This includes at Mount Ontake, site of Saturday's deadly volcanic eruption. Japan's NHK World reports that 47 people have been confirmed dead since Saturday's eruption, the worst volcanic disaster in post-war Japan.
Debris flows resulting from the torrential rain and ash are a serious concern around the volcano, further hindering the search for additional victims.
Douty continued that the "southeastern coast of Shikoku and the southern coast of Honshu are at greatest risk of enduring typhoon conditions."
These areas will be subject to wind gusts between 130 and 160 kph (80 and 100 mph) despite Phanfone weakening. Such winds will lead to widespread tree damage and power outages, as well as damaging some structures.
Extremely dangerous seas will build over the ocean south of Japan with an inundating storm surge threatening the southern Honshu coast.
It is possible that Phanfone's center tracks just south of mainland Japan. While this scenario would lessen the wind and storm surge impacts across southern Japan, the same cannot be said for the flooding rain threat.
A track farther north and more inland than expected would also cause the damaging wind threat to also expand in a similar fashion. This scenario could put Tokyo at risk for wind gusts to 130 kph (80 mph) and the city's ports and communities that line the Tokyo Bay at risk for coastal flooding.
Residents throughout mainland Japan should continue to check back with AccuWeather.com for the latest updates on Phanfone and heed any evacuation orders that get issued.
Beyond Monday, Phanfone will lose its tropical characteristics across the northern Pacific Ocean.