Complex sentence: Situated west of Nome, Alaska, the powerful storm subsequently weakened and slowed on October 19.By October 20, the system filled to 980 mb (hPa; 28.95 inHg) low and reached a position west of Kotzebue, Alaska.
Split into simpler sentences: Situated west of Nome, Alaska, the powerful storm subsequently weakened and slowed on October 19. The weakening storm was last noted on October 20 as a 980 mb (hPa; 28.95 inHg) low approximately west of Kotzebue, Alaska.