Popular Southland newscaster Jess Marlow will replace Keith Morrison as co-anchor on the 5 p.m. broadcast of KNBC-TV's "Channel 4 News," the station announced Monday. Marlow, recipient of six Golden Mike awards from the Radio and Television News Assn. of Southern California, left KNBC in 1980 for KCBS Channel 2, where he co-anchored the 5 p.m. news and the "Heart of the Matter" segment during the 6 p.m. news broadcast. He returned to KNBC last November as a news commentator. Morrison will remain as anchor on KNBC's 11 p.m. broadcast.