In what is turning out to be an unusually cold and dry season; the latest medium to long range forecast is for more of the same for much of California and the West.
Strong high pressure probably resulting from below normal ocean temperatures along and off the western coast of North America is likely to continue its influence from the Rocky Mountains westward for at least the next 10 to 14 days. The net result is that storm centers which normally might spread needed and significant rain into California are being diverted—away from and east of the Los Angeles area.
The storm track is expected to continue to be such that waves of energy dropping south and eastward from the Gulf of Alaska fail to intensify until they are east of Southern California. The all-too-familiar “inside slider” weather pattern is for the most part a dry one, until each disturbance is affected by the topographic uplift of higher mountainous terrain in the Great Basin and Rocky Mountain states.
Winds aloft continue to be from the northwest and north, spreading frigid arctic air at mid to upper levels which mixes down to the surface and is further reinforced with each passing minor “short-wave” disturbance.
This overall pattern is expected to persist for another 10 to 14 days, with the next disturbance expected into Southern California this Thursday, January 10th. This cold upper level low pressure system and associated surface low over Nevada should bring another round of cold, showery weather to the Southland, with low mountain snow levels once again. Amounts will likely be light, and strong northwest winds can be expected across much of Southern California and adjacent regions.
Current models suggest this disturbance may be multiple in nature, with two additional minor waves serving to amplify the system, rotating in behind Thursday's initial disturbance. This will serve to maintain a strong, cold northerly flow at all levels, and keep cold Arctic air “locked in” across the entire western U.S. until mid-January, when higher pressures surface and aloft may build in to introduce a stable and warmer air mass.
Regional winter weather/storm advisories, watches/warnings are a good bet starting around mid-week for much of California and parts of neighboring states. Frost and freeze warnings will be equally likely.