 Upon entering the western North Pacific Ocean , tropical cyclone warning duties transferred from the CPHC to the Japan Meteorological Agency ( JMA ) , and the JMA first assessed Paka as a 65 km ( 40 mph ) storm . The Joint Typhoon Warning Center ( JTWC ) unofficially assumed warning duties for interests in the United States Department of Defense . Paka continued to intensify after crossing the date line , and from late on December 7 through early the following day it remained a strong tropical storm . However , upper @-@ level wind shear increased , and it again weakened . At 1200 UTC on December 9 , the JTWC assessed Paka as an 85 km / h ( 50 mph ) tropical storm and forecast it to continue weakening . By December 10 , the shear had begun to decrease as the storm moved through the Marshall Islands , and that night the JTWC upgraded Paka to typhoon status . Paka officially attained typhoon status when JMA classified it with winds of 120 km / h ( 75 mph ) at 0000 UTC on December 11 . 
