Warmer through early next week with a shallower marine layer and periods of weak offshore flow. Warmest days are expected to be Sunday and Monday, with the strongest offshore winds on Sunday. Cooler conditions expected by the middle to end of next week. Cloudy, cooler, windier, and potentially wetter towards the end of next week, with low confidence in details.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
This morning, The marine layer is about 2500-3000 ft deep with widespread low clouds extending 15-20 miles inland. Sfc pressure gradients are weakly offshore with -4.7 mb SAN-TPH and trending stronger. At this time, diurnal slope winds are prevalent but weak offshore flow is expected to develop this morning. The clearing of low clouds today could be faster than yesterday as the offshore flow develops.
After the inland passage of a weak shortwave trough, a ridge of high pressure will build over the west coast. The ridge will reach maximum amplitude on Sunday. The ridge will combine with offshore flow to produce a warming trend through next Monday which will likely be the warmest day. Daytime high temperatures on Monday will likely reach the low 90s for the inland valleys and lower deserts, with upper 70s to low 80s in the coastal areas. These temperatures are as much as 12-17 degrees above seasonal averages. The ridge will also make the marine layer much shallower, confining the low clouds and fog to the immediate coastal areas. Strengthening offshore pressure gradients will produce locally gusty Santa Ana winds, mostly along the coastal mtn slopes and in the passes and canyons. The northeast to east winds will be strongest on Sunday when gusts of 30-40 mph are expected in the favored locations.
As the pattern amplifies, a deepening trough over the eastern Pacific will develop a closed upper low about 1400 miles west of San Diego on Sunday afternoon. This low will remain nearly stationary until Wednesday when a more vigorous low pressure trough will move out of the Gulf of Alaska and move towards the west coast. The two low pressure systems will merge as they move east, weakening the ridge and displacing it to the east. The resulting large low pressure system will bring cooler conditions, onshore flow, increasing clouds and the chance for widespread precipitation for next Thu-Fri. Forecast details are still very uncertain but an increasing number of ensemble members are beginning to favor a wet solution.
071030z, Coasts/Valleys, Low clouds based 800-1600 feet MSL and tops to 2000 feet will continue to cover coastal areas and infiltrate into parts of the inland valleys this morning. Low clouds will clear to the coast 16-18Z. Lower CIGs 600-1000 feet MSL will redevelop after 01Z in San Diego County and after 06Z in Orange County, but remain only in coastal areas. Vis reduced 3-5SM on higher coastal terrain.
Mountains/Deserts, Clear and VFR conditions today and tonight.
No hazardous marine conditions are expected through Tuesday.
West-northwest swell with a period of 14 to 15 seconds will generate surf of 3 to 6 feet, with sets 7 to 8 feet. Highest surf will be south of Del Mar this morning. Elevated surf combined with high tides could lead to minor tidal overflow. Check the Beach Hazards Statement for more details.
Ca, Beach Hazards Statement through late tonight for San Diego County Coastal Areas.
Beach Hazards Statement until 1 PM PST this afternoon for Orange County Coastal Areas.
PZ, None.
