Wensum Park has been closed to the public since Saturday.
Since then, police, with the help of the fire service and coastguard, have been scouring the area looking for clues.
On Tuesday, Rosie Richards, a woman who lives nearby, said she saw a woman matching Ms Lord’s description in the park at about 16:00 on Friday.
She said: “It’s really upsetting… I’m just thinking of her friends and family, because she is a sort of similar age to my mum and that would be awful to be going through what they are going through right now.”
Police said Ms Lord’s family was being supported by specialist officers.
Ms Lord is described as white, 5ft 6in (1.67m) tall and with blonde, shoulder-length hair in a bob.
When she was last seen she was wearing a white shirt, yellow tank top, large olive-coloured coat and a scarf, police said.
