The incident on July 20 is one of several indecent exposure offences reported at the address in Pontefract, all of which are believed to involve the same man.
It happened when the 72-year-old victim was in the garden of her home in North Baileygate at around noon.
The man approached her and indecently exposed himself, but ran off after a few seconds when he was challenged by the woman.
PC Ian Heaslip, of Pontefract Neighbourhood Policing Team, said: “Enquiries remain ongoing regarding these serious, repeat offences and we would like to speak to anyone who can help us identify a suspect.
“The victim has been caused understandable distress and it is important we identify and catch this individual.”
Anyone with information is urged to call PC Ian Heaslip on 101 or Crimestoppers in confidence on 0800 555 111, quoting crime number 13170337816.