Patchy marine layer low clouds and fog can be expected overnight and in the morning as high level clouds from Tropical Cyclone Marie move over the area this weekend. Periods of light to locally moderate precipitation are possible, highest chances on Sunday. There is a slight (5-10%) chance of thunderstorms, mainly over the San Bernardino Mountains and High Desert on Sunday afternoon. Warming high and low temperatures through the middle of next week. Slight chance of mountain showers and thunderstorms return for mid-week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Tropical Cyclone Marie is about 800 miles south of San Diego, CA this morning. A swath of high clouds and moisture from the cyclone have made their way into Southern California. The only radar returns over SoCal as of 11 AM were in Imperial County. As Marie continues to track north and west this weekend, additional moisture will be pushed into the area increasing chances of showers. The highest chances are tomorrow north of San Diego County. Total rainfall amounts may reach over a half an inch over the San Bernardino Mountains, and generally 0.20 to 0.30 inches for the Inland Empire, with slightly lesser amounts to the coastal areas of Orange County, tapering off to lesser amounts over San Diego County. It's possible some areas in southern San Diego County may not see any accumulating rainfall. There is a 5 to 10 percent chance of thunderstorms over the San Bernardino Mountains and High Desert Sunday afternoon. Drier conditions expected for Monday and Tuesday.
For this weekend, high temperatures will remain below average inland with highs near the coast running a few degrees above average. Overnight lows will also return to above average for this time of year by Sunday. By Tuesday, high temperatures will be within a few degrees of average for the mountains and deserts and 3 to 8 degrees above average for the coast and valleys. Above average low temperatures will be maintained into next weekend. Widespread minor to moderate HeatRisk is expected for inland areas Wednesday and Thursday. Temperatures will peak on Wednesday and gradually cool into Friday.
The upper level flow turns southeasterly Wednesday and Thursday, which may allow for some additional moisture to creep into the area. There still remains some uncertainty in the upper level pattern with the position of the upper level ridge over the southwestern US and a trough off the US West Coast. A more easterly position of the trough would result in drier conditions with a more westerly position of the ridge allowing more moisture into the area. Current forecast follows the NBM which has 20 to 40 percent chance of showers and a 15 to 20 percent chance of thunderstorms over the mountains Wednesday and Thursday afternoon.
051800z, Coast/Valleys/Mountains, Mid and high level clouds around 10,000-15,000ft MSL continue to stream into the area associated with Hurricane Marie. SCT-OVC of these high clouds will continue for much of today and tomorrow. -SHRA or VCSH generally after 03z Sun for Orange County, increasing in coverage to most locations after 11z. Brief periods of 4-6SM and BR as well as BKN-OVC at 5000ft MSL or lower with any SHRA. Marine layer clouds will struggle to develop due to the moisture encroaching from the southwest, but there may be some localized spots of lower level clouds around 2500ft MSL, likely near the coast, overnight tonight. In the mountains, TSRA may briefly occur, especially in the San Bernardino Mountains 18z-00z Sun.
Deserts, Breezy southwest winds increase around 20z today, with intermittent gusts up to 35 knots on the desert slopes of the mountains. Winds weaken after 03z Sun. Mid-level clouds AOA 10,000ft MSL increase this afternoon, becoming BKN by late evening/early Sunday. VCSH for much of Sunday with brief -SHRA. Otherwise, VFR with no significant impact expected.
No hazardous marine conditions are expected through Wednesday.
A large south swell from Hurricane Marie will move into the region today, peaking Sunday into Monday, before gradually diminishing Tuesday. This will result in elevated to high surf and strong rip and longshore currents at majority of beaches. Additionally, waves will occasionally run much farther up the beach than expected, especially during increasing and high tides.
For south and southwest-facing beaches, expecting high surf 6-10 feet. This includes Orange County and north San Diego County beaches. For west-facing beaches, expecting elevated surf 4-7 feet. This includes most of southern San Diego County beaches.
High surf combined with high astronomical tides 6.2 to about 6.8 feet will lead to tidal overflow and coastal flooding through Tuesday during evening high tides, especially for those south and southwest-facing beaches as well as low-lying areas.
Ca, Coastal Flood Advisory until 11 PM PDT Tuesday for Orange County Coastal Areas-San Diego County Coastal Areas.
High Surf Advisory until 11 PM PDT Tuesday for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
