Blustery conditions expected; rain possible, snow in higher elevations.
Strong high pressure over the western U.S. will give way to a developing cold upper level storm system by mid-week if current forecast models verify.
Above normal temperatures and dry conditions this weekend will gradually be replaced by cooler temperatures and an onshore flow as surface low pressure develops over the U.S. western interior beginning late Tuesday.
Upper air prognostics suggest that a fast-moving cut-off low or “inside slider” will drop south over the California Sierras beginning Wednesday morning, and be located over western Arizona by Thursday. Available moisture tends to be limited with this type of pattern, precipitation is generally expected to be light and scattered.
The system is however, expected to be a cold one, with strong west and northwest winds from the surface up through 30,000 ft. Snow showers will be likely in the higher elevations of California's Sierra Nevada and the mountains of Nevada, Utah and north central Arizona. Snow levels are typically near 5-6,000 ft with these systems, and winter weather watches and advisories may be needed in these areas beginning late Wednesday.
For Los Angeles, expect a deepening marine layer beginning Tuesday, with much cooler temperatures by mid-week, along with a chance of scattered showers. Wind advisories may be needed by Wednesday in mountain and desert areas as surface pressure gradients tighten, supported by increasing westerly winds aloft.