Cloudy and cooler through Monday, along with a slight chance of light showers for our southeastern regions through early Monday. The trough of low pressure moves through Southern California on Monday, bringing back the marine layer and breezy conditions to the mountains and deserts. Weak high pressure will then bring dry and warmer weather Tuesday into next weekend, with a shallow marine layer for coastal low clouds during the nights and mornings.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
This afternoon, Satellite imagery shows widespread mid and high clouds covering the region. These clouds are associated with the moisture plume from the weakening tropical cyclone Odalys. The moisture is being drawn into SoCal by the southwest flow aloft. Low clouds south and east of Orange County can't be seen in the satellite imagery but a few locations in the south-coastal areas of San Diego County are reporting patches of low clouds. Temperatures are generally lower than at this time yesterday with a few locations in the inland valleys and mountains as much as 10-15 degrees cooler.
Circulation around a low pressure system moving in from the northwest will maintain the southwest flow over SoCal until the upper low moves east late Monday night. Meanwhile, the mass of clouds moving in from the southwest will continue to bring slight chances for light precipitation into Monday. Not much accumulation is expected and will most likely occur in the mountains of San Diego County. Even there, rain totals are unlikely to exceed one tenth of an inch. This low pressure system will also bring cooler weather with stronger onshore flow. Monday will likely be the coolest day of the week, with daytime high temperatures near normal at the coast, 5-7 degrees below normal in the inland valleys and deserts, and as much as 10-15 degrees below normal in the mountains. The onshore flow will be strongest on Monday with westerly winds gusting 30-40 mph in the wind-prone areas of the mountains and adjacent deserts slopes. Onshore winds will weaken late Monday.
The upper low will move east on Tuesday and a drying and warming trend will begin as high pressure builds in from the west. Northerly flow aloft on the upstream side of the low will combine with weak offshore pressure gradients to produce a relatively brief period of offshore flow on Tuesday. The position of this low pressure system will keep any moisture from Polo well to our south and east.
The dry and warm weather will continue into next weekend as the high pressure ridge settles over the Southwest. Daytime high temperatures will return to above normal by Wednesday but the warmest day will likely be Saturday. High temperatures on Saturday will likely be 2 to 7 degrees above normal in the mountains and deserts, and as much as 15 degrees above normal in the inland valleys and coastal areas. The marine layer will be shallow and any low clouds will likely be restricted to the coastal areas during the nights and mornings.
271800z, Coast/Valleys, Layers of BKN-OVC mid/high clouds 15,000- 25,000ft MSL will continue for much of the TAF period. FEW-SCT patches of low clouds near 1,000ft MSL may linger near the coasts through the afternoon. These low clouds will remain very patchy the the overnight period, with very low chances for long duration CIGs at the coastal TAF sites. Mid/high cloud cover is set to decrease in coverage Monday afternoon.
Mountains/Deserts, VFR prevails with BKN-OVC clouds 10-20 kft through the period. Pockets of -SHRA possible between 00-14Z Monday. Little to no surface impacts expected, but some brief lower CIGs below 5000ft are possible. Best chance in eastern San Diego County.
Northwesterly flow gusting to 20-25 knots in the outer waters is expected Monday afternoon and evening. A Small Craft Advisory has been issued for this hazard. Additionally, choppy, mixed seas is expected Monday afternoon/evening. Winds and the choppy seas are set to diminish Sunday night into Monday. No hazardous marine conditions are expected Tuesday onward.
Southwesterly swell (3-4 ft at 13 seconds from ~200 degrees) from Hurricane Odalys persists today into Monday, bringing surf of 3-5 feet with sets up to 6 feet, highest along south and southwest facing beaches. A swell from Hurricane Polo (~4 ft at 12-13 seconds from 160-170 degrees) then increases on Monday. Given this direction, most of San Diego County beaches will be largely sheltered from this swell, but Orange County beaches (especially in north OC) should be impacted. Meanwhile, a northwesterly swell (3-4 ft at 7 seconds from ~280 degrees) arrives later today and Monday. Between these two swells, surf of 3-5 feet with sets to 6 feet looks probable along south/southwest facing beaches with surf 3-5 feet along west-facing beaches through Tuesday. With this elevated surf, there is a high risk for rip currents through Tuesday.
Tides are already observed over 6.8 feet and are expected to peak around 7.0ft for the late-morning high tides on Monday-Wednesday, highest on Tuesday. A Beach Hazard Statement remains in effect through tonight due to the risk of minor tidal overflow and minor coastal erosion. A Coastal Flood Advisory is in effect from early Monday morning through Wednesday afternoon to account for the highest tides combining with the expected elevated surf. Primary impacts during the morning high tides Monday-Wednesday will be minor coastal flooding in low lying areas in addition to coastal erosion.
Please note - listed tide predictions have been adjusted to reflect actual measured tide observations.
Ca, Beach Hazards Statement through late tonight for Orange County Coastal Areas-San Diego County Coastal Areas.
Coastal Flood Advisory from 5 AM Monday to 5 PM PDT Wednesday for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, Small Craft Advisory from 11 AM to 11 PM PDT Monday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
