A low pressure system from the north will bring cool temperatures, gusty southerly winds and widespread precipitation to Southern California today. Clearing tonight leading into quiet weather and gradual warming through the weekend. Another low pressure system from the north will bring cooling early next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
The upper low can be seen moving down the California coastline this morning on satellite. Showers with moderate rainfall rates have already spread into the northwestern portions of the coastal basin and mountains. The cold front along with the heaviest precipitation is pushing through Los Angeles currently. High temperatures will range from 15 to 25 degrees below average for inland areas today.
As the front approaches this morning, gusty southerly winds associated with the LLJ will continue to ramp up for all areas. Widespread 25-35 mph gusts through the coastal basin with locally higher gusts in the mountains and deserts. Gusts locally to 50 mph for the High Desert. The main band of precipitaiton will push across the area today beginning shortly for northwestern parts of the area including OC and the western Inland Empire and pushing south and east through the day. Moderate to locally heavy rainfall rates expected for the coast to the mountains. Orange County, western Inland Empire and surrounding coastal slopes are particularly at risk for isolated rainfall rates 0.5-0.8" per hour. Elsewhere, rainfall rates 0.3-0.6" per hour locally from the coast to the mountains. A few embedded thunderstorms are possible, mainly north of San Diego County. Strong low level shear will allow for a marginal severe wind risk with any storms that develop in Orange County.
Total rainfall will range from 2-4 inches along the coastal slopes of the San Bernardino County Mountains, to less than a tenth of an inch for the lower deserts. 0.75-1.5" for most of the coastal basin except lower amounts ranging 0.25-0.75" for the eastern Inland Empire and the southern half of San Diego County. Accumulating snow for elevations above 7500 feet. No impacts expected at mountain resort levels.
Scattered post-frontal showers developing this evening across the coastal basin, but any additional rainfall should remain light with minimal impacts. Clearing expected from west to east across the area tonight as the low pressure system exits the region.
Much more benign weather will follow as a weak ridge builds into the southwestern US leading to dry conditions and gradual warming through the weekend. A surface high will move over intermountain west by Wednesday and should create enough of an offshore pressure gradient to prevent marine layer cloud development for a few days.
By early next week another upper level trough will swing across the western US. This should bring temperatures back to below average, but impacts beyond that are uncertain at this time.
141615z, BKN-OVC clouds continue to lower from north to south this morning with bases 2500-3500 ft MSL. -RA over northern areas will continue to push southward throughout the day. VCTY KSAN/KCRQ bases near 5,000 ft will lower after 18Z. SCT -SHRA will become steadier RA/+RA along with an iso TSRA from north to south late morning through the afternoon. Vis reduced 2-5SM in +RA. -SHRA becoming more intermittent 00-10Z, drying out there after with scattering clouds.
S/SW winds along the coast will gust up to 30 kts until 23Z. Gusts 30-40 kts in the mountains and desert slopes until 06Z Wed. MOD UDDFS and local LLWS or rotors in lee of mountains such as vcnty KPSP. Local vis reduced 3-5SM in BLDU in deserts through 22Z.
Strong southerly winds will continue this morning in advance of a front that will move west to east through the coastal waters from late morning through afternoon and create conditions hazardous for small craft (check the Small Craft Advisory for details). Weaker westerly winds will follow behind the front. Additionally, there is a slight chance of thunderstorms today. Any thunderstorm could produce briefly gusty, erratic winds, choppy seas, and lightning. No additional hazardous marine conditions are expected this evening through Saturday.
There is a slight chance of thunderstorms and lightning today, most likely in the afternoon. Surf today will be 3 to 5 feet, with occasional sets to 6 feet, highest in San Diego County. This will produce a high rip current risk.
Ca, Wind Advisory until 3 PM PDT this afternoon for San Diego County Coastal Areas-San Diego County Valleys.
Wind Advisory until noon PDT today for Apple and Lucerne Valleys- Orange County Coastal Areas-Orange County Inland Areas-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire.
Flash Flood Watch until 5 PM PDT this afternoon for Orange County Inland Areas-San Bernardino County Mountains-Santa Ana Mountains and Foothills.
PZ, Small Craft Advisory until 5 PM PDT this afternoon for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm-Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
