Cold, clear weather continued across the western U.S. Saturday as strong surface high pressure covered the region. Widespread single digit readings were reported again as cold arctic air remains in place over the western two thirds of the nation. The long-wave or meridional pattern of upper level winds and pressures can be very slow to shift, but prevailing high pressure over the eastern Pacific should slowly reposition itself, becoming centered along the U.S west coast toward the middle of next week.
In response to this, the cold, tight northerly flow aloft will gradually shift east and modify, allowing milder temperatures aloft to filter into the western U.S. weather picture. Subsequently, surface temperatures will follow suit, and by the middle of next week, moderate offshore (Santa Ana) winds will bring compressional warming to much of coastal southern California. Thermal low pressure along the California coast will result, but very cool temperatures will continue across mountain and desert areas, but in greater Los Angeles, daytime highs are expected to be in the low 70's beginning next Wednesday.
Long range indications are that significant change to a potentially moist westerly flow may introduce the possibility of some wet weather to the region during the last week of January.