Cold air trapped at low elevation is putting some extra chill in the air and challenging public works crews as they attempt to clear roads of snow that has compressed and turned to ice.“Crews have continued to plow what they could from major streets and some side streets,” said a statement from Vancouver Public Works on Saturday. “But at this point, what’s on the surface is so compacted and frozen that progress is limited.”With continued cold temperatures likely through Monday, that situation isn’t expected to change soon.“Given the compaction and temperatures, it’s very slow going, as is the thaw,” the statement said.Temperatures in Vancouver fell to 8 degrees Saturday for the second day in a row, despite forecasts that called for lows in the upper teens. National Weather Service meteorologist Evan Bentley explained that’s because east winds out of the Columbia River Gorge eased overnight, allowing cold air to settle close to the surface.“Winds coming out of the Gorge keeps the atmosphere mixed up,” Bentley said. “Winds went calm for one hour, and the temperature dropped 10 degrees.”Vancouver wasn’t the coldest spot in the metro area. That honor went to Hillsboro, Ore., which recorded a temperature of 4 degrees, breaking a record established in 1930.