A warming trend will continue through Wednesday when temperatures will reach about 10 degrees above average for inland areas. This will be followed by a cooling trend through Sunday, with high temperatures as much as 10 to 15 degrees below average for the higher mountains and portions of the inland valleys. A low pressure system from the northwest will bring increasing chances of showers for late Friday through Saturday along with a chance of thunderstorms on Saturday. Chances for additional showers will continue into late Sunday or Sunday night, but with lower confidence in the details. The chance of wetting precipitation from the coast to the mountains for the weekend is around 80 percent. There will be stronger southwest to west winds for the mountains and deserts on Thursday and Friday with gusts of 35 to 45 mph in the wind-favored areas. There could be another round of west to northwest winds of similar strength on Sunday. Then drier with a warming trend for early next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Skies are clear this afternoon under a transient ridge of high pressure. The marine layer is about 2000 feet deep with a moderately strong inversion. With the help of a weak coastal eddy, low clouds covered most of the coastal areas this morning and extended 10-15 miles inland before clearing out by about 11 am.
The upper level ridge will continue a warming trend for inland areas through tomorrow (Wednesday) where daytime high temperatures will be about 10 degrees above average. The marine layer will persist and may deepen a little with the help of the coastal eddy, allowing low clouds to spread a little farther inland tonight.
A cooling trend will begin on Thursday and onshore flow will start to strengthen as a cold and vigorous low pressure system approaches from the northwest. High temperatures on Thursday will mostly be a few degrees lower than on Wednesday. High temperatures on Thursday will range from around 70 near the coast to the mid 70s to lower 80s for the valleys with the lower deserts in the lower to mid 90s. The stronger onshore flow will drive low clouds farther inland as the marine layer deepens, potentially all the way to the coastal mtn slopes.
The low pressure system will bring increasing chances for showers late Friday through Saturday along with a slight chance of thunderstorms on Saturday. A reinforcing shortwave embedded in the mean northwest flow along the west coast could bring additional showers through Sunday or Sunday night but with greater spread in the model solutions and resulting forecast details.
Through Saturday night, chances for measurable precipitation range from around 65 percent toward the coast to 80 percent in the mountain with chances for one inch or more of rainfall in the mountains around 30 percent and for one-half inch or more for coastal areas around 20 percent. The snow level will lower to around 6500 feet late Saturday and 6000 feet on Sunday.
Dry and warmer weather is expected for early next week even though we will remain under the influence of broad troughing aloft.
071730z, VFR conditions currently dominate all coastal and inland TAF sites. Low clouds around 800-1200 feet MSL will develop after 06Z and expand through coastal areas overnight into Wednesday. These clouds should begin to scatter out tomorrow morning around 16-18Z from east to west.
Occasional wind gusts in the outer waters should exceed 20 knots Wednesday night. There is a 20% chance of thunderstorms Friday night and Saturday. Otherwise, no hazardous marine conditions are expected through Saturday.
Ca, None. PZ, None.
