The swelter that has settled in throughout California shows no sign of relenting this week, weather officials said. Temperatures are expected to soar into the upper 90s throughout the week in much of the lower elevations of western Nevada County, according to forecasts provided by the National Weather Service, Sacramento. "The temperatures will slowly, very slowly, trend downwards starting Wednesday," said Stefanie Hunter, meteorologist with the National Weather Service, Sacramento. The slow-cooling trend is expected to continue until Monday, when forecasts call for the extreme heat to break a little, as temperatures may dip below the 90 degree barrier. Currently, …