(CNN) -- The Philippines could begin feeling the effects of a powerful typhoon churning toward the island chain as early as Sunday, forecasters said Saturday.
Typhoon Megi, also known as Typhoon Juan, is expected to make landfall by Monday in northern Luzon at or near super-typhoon strength with winds possibly in excess of 200 kph (124 mph), according to the Philippines' Science and Technology Secretary Mario Montejo.
Strong winds and storm surge were the largest concern.
As of 4 p.m. Saturday, Megi was located 820 km (510 miles) east of northern Luzon with winds of 140 kph (87 mph) with higher gusts, the Philippine Atmospheric, Geophysical and Astronomical Services Administration reported.
Montejo said the government is alarmed by the speed and strength of the typhoon. He warned of potentially devastating effects the storm may wreak in Luzon.
As the storm moves across the rugged terrain of Luzon, it is expected to decrease in intensity before moving out over the South China Sea. Megi is expected to dump large amounts of rainfall over the mountains, which could potentially trigger mudslides and localized flooding.
CNN's Judson Jones contributed to this report.