SOUTHLAND A fair weather ridge will slowly weaken and push eastward this week, allowing a dip in the jet stream to develop. The result will be a slow cooling trend and a slight chance of rain in Southern California. Abundant high clouds cooled the Southland Sunday. But, sunshine should return Monday giving thermometers a boost ahead of a mid-week cool down and a 20 percent chance of showers by Thursday. Halloween looks to be sunny, breezy and a little warmer. That will carry over into the opening of November and the return of Pacific Standard Time.