A strengthening upper-level ridge
of high pressure is the culprit - or the benefactor, depending on your view of extremely hot weather - for the continued high temperatures.
The heat is the result of an upper-level ridge
of high pressure that began building Saturday and centered over Southern California, according to the NWS.
An upper-level ridge
of high pressure - a really strong one - has built up over us, moving basically from the southeast Nevada desert," said meteorologist Wanda Likens at the Weather Service office in Portland.
The explanation from the National Weather Service in Portland is that an upper-level ridge
of high pressure is building just off the Pacific Northwest coast, and is combining with a surface-level trough of low pressure near the coast to create a warm air mass.