- NEW: Bolaven has begun landfall over Okinawa
- NEW: It will likely be the strongest typhoon in five decades
- More than 400,000 people in the area live in elevations between zero and 50 meters
- Typhoon Bolaven's cloud field is about 20 times the length of Okinawa
Tokyo (CNN) -- A massive typhoon began to make landfall Sunday over Okinawa, bringing winds more ferocious than even the typhoon-weary Japanese island has seen in decades.
It will likely be the strongest since 1956, said CNN International meteorologist Tom Sater.
With a cloud field of 2,000 kilometers (1,250 miles), Typhoon Bolaven is 20 times larger than Okinawa's length.
"It's been very, very severe," said storm chaser James Reynolds, on the northwestern coast of the island.
Tree branches were flying through the air amid torrential rain, he said.
The infrastructure on Okinawa is designed to withstand violent storms. "Everything's made of solid concrete," said Reynolds.
"Utility poles are so wide you couldn't even put your arms around them," Reynolds said. "All the houses are built with concrete. There's no such thing as a beach house in Okinawa because it would just get destroyed by a typhoon."
Still, the power was out where he was Sunday.
On Sunday evening, Bolaven was carrying sustained winds of 213 kilometers (132 miles) per hour, with gusts reaching 259 kilomeers per hour (161 mph) -- the highest since Typhoon Naha in 1956.
Bolaven was traveling northwest at 15 kilometers per hour (9 mph).
The storm is on course to hit China and the Korean peninsula.
It's "roughly the size of France to Poland in land mass," said Sater.
"The typhoon is producing wave heights of 16 meters high, so the possibility is there for a storm surge of 8 to 10 meters high on the coastline. Wind gusts will be strong enough to not only uproot or down trees and power lines, but could flip automobiles.
"Okinawa is 100 kilometers (62 miles) long. The size of Bolaven's eye is roughly 30 kilometers (19 miles) in width. This means many residents could experience the eye passing over them; unfortunately, that means putting up with the strongest winds the storm can produce, followed by a calm period with a brief clearing of the skies overhead, then another chaotic period of damaging winds that will be blowing in the opposite direction of the previous winds."
Rainfall totals could top 500 mm (20 inches) in 24 hours, said Sater.
Storm surges are expected to be a major problem for Okinawa. Highways on low-lying barrier islands could be completely washed out, with surges at the coast expected at about 8 meters (26 feet) high.
More than 400,000 people in the area live in elevations less than 50 meters (164 feet).
Some low-lying areas have been evacuated.
"The storm will continue with typhoon strength into the East China Sea, then into the Yellow Sea with its eyes on the Korean Peninsula," Sater said.
Taiwan could be in for a pounding due to something called the Fujiwhara effect, he said.
Typhoon Tembin made landfall in southern Taiwan a few days ago, and was expected to work its way toward Hong Kong. But Bolaven, which is much stronger, has stopped Tembin's movement toward Hong Kong and has been spinning it around. Tembin is likely to make a second landfall in soutehrn Taiwan.
"As Typhoon Bolaven moves northward towards the Yellow Sea, it will drag Tembin toward the China coast very near Shanghai," said Sater. "That's an amazing change in direction."
CNN meteorologist Pedram Javaheri contributed to this report.
