Below average temperatures with marine layer low clouds and fog reaching into portions of the valleys this weekend. For the first half of the week, widespread moderate to areas of major HeatRisk possible for the deserts and widespread minor to locally moderate HeatRisk for inland Orange County, valleys, and mountains. The marine layer will become shallower next week, staying confined to coastal locations. Gradual cooling expected for the second half of the week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
At 11:30 AM, temperatures were running 3 to 7 degrees warmer than yesterday in the Inland Empire, San Bernardino mountains, and inland Orange County with temperatures similar to a few degrees cooler than 11:30 AM yesterday elsewhere. Visible satellite is showing partial clearing along the immediate coast, with the potential for widespread clearing this afternoon. Low clouds are expected to reach into portions of the valleys again overnight into Sunday morning. Highs Sunday are expected to remain below average but will trend a few degrees warmer than today.
Additional warming is expected into the middle of the week as a ridge of high pressure builds aloft from the south. Current forecast has high temperatures for inland locations 5 to 10 degrees above average with localized areas of moderate HeatRisk away from the coast and areas of major HeatRisk in the low desert by Wednesday. The forecast has trended cooler by a few degrees for Tuesday through Thursday, which has limited the geographic extent of moderate HeatRisk in the valleys and major HeatRisk in the low desert. Based on the current forecast, hottest day is expected to be Wednesday with Tuesday and Thursday a few degrees cooler than Wednesday.
Guidance continues to indicate an increase in precipitable water for the middle to end of next week. This will most likely result in limited daytime heating, warmer than normal overnight low temperatures, and more humid feeling conditions. As far as the marine layer goes, the building high pressure and influx of moisture will result in a shallower marine layer and limited low cloud development. While the most likely scenario is for dry conditions to prevail, there is a 10-15 percent chance showers or thunderstorms may develop over area mountains Wednesday afternoon.
Most ensemble solutions are now on board with a shortwave trough moving into the Pacific Northwest by Thursday. This will displace the ridge aloft and result in a gradual cooling. By next Saturday, conditions are expected to be within a few degrees of normal.
201800z, Coast/Valleys, Low clouds have be scattering out more efficiently across coastal San Diego County this morning compared to Orange County, with CIGs likely to persist at KSNA until 19-20z. VFR prevailing into the afternoon with low clouds set to redevelop and fill back ashore around 01-03z Sunday, initially at KSAN/KCRQ, eventually spreading to Orange County (KSNA) and the inland valleys by 09z. Higher chance for CIGs to spread into the Inland Empire compared to this morning, with a ~60% chance for CIGs at KONT between 12-16z and a ~30% chance at KSBD. Cloud bases will be similar to last night/this morning, likely 1700-2000ft MSL during the early overnight hours, then lifting to 1900-2300ft MSL around 12z. Clouds set to scatter back to the coasts around 17-18z Sunday.
Mountains/Deserts, VFR conditions expected through the TAF period. Westerly wind gusts of 25-40 kts pick up through mountain passes into deserts after 20z this afternoon. Local VIS reductions 4-6 SM in BLDU during periods of strong gusts and moderate up/downdrafts in lee of mtns.
No hazardous marine conditions are expected through Thursday.
Elevated surf and strong rip currents are set to continue through this weekend with a persistent long period southwesterly swell. Surf of 3-5 feet with local sets to 6 feet are expected at southwest- facing beaches. Expect locally hazardous swimming conditions with high rip current and longshore current risk. See the Beach Hazards Statement for more details.
Ca, Beach Hazards Statement through Sunday evening for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
