Police requested motorists using the Southern Expressway to be cautious over misty conditions between Pinnaduwa and Welipenna interchanges.The Police Spokesmans Office states that thick misty conditions had been observed between the Welipenna interchange and the Pinnaduwa interchange on the Southern Expressway during the morning over the past couple of days as well as today.Therefore, motorists passing through that area are advised to remain cautious and avoid traveling at high speeds, police said.