 Tropical Depression Nine @-@ E strengthened into Tropical Storm Hernan on July 21 while 684 mi ( 1 @,@ 100 km ) south of Cabo San Lucas . The tropical storm continued to strengthen and as it moved to the northwest , and became a hurricane late on July 21 . Hernan continued to strengthen and as it passed 145 mi ( 230 km ) southwest of Clarion Island . On July 23 , Hernan reached its peak strength of 155 mph ( 250 km / h ) and minimum pressure of <unk> mb ( 27 @.@ 4 inHg ) as the center of circulation was 207 mi ( <unk> km ) south @-@ southwest of Clarion Island . On July 24 , concentric <unk> ( one eyewall located inside another ) formed around the center of Hernan , which was the first time this pattern had been observed with an eastern Pacific hurricane . 
