A warming trend will continue through through Monday, with a shallower marine layer. Night and morning low clouds will be restricted to the coast areas and adjacent valleys through this period. Temperatures will peak on Monday around 10 to 20 degrees above normal for inland areas with areas of moderate to high heat risk. A cooling trend with a deepening marine layer will return by the middle and end of next week as an area of low pressure approaches the West Coast.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
The marine layer continues to thin as inland extend was a bit less this morning than yesterday morning. Low clouds should slowly dissipate after sticking to the Orange County beaches currently. High pressure off the coast will begin to build through Monday, which will suppress the marine layer even further. This will keep low clouds and fog within 10-15 miles of the coast. This system will also bring a warming trend to the region through Monday. High temperatures will increase a couple degrees again on Sunday with greater warming on Monday. By Monday, model guidance is in fair agreement with high temperatures reaching 105 to 110 degrees across the lower deserts and 95 to 100 degrees across the Inland Empire. Heat alerts have been issued for these areas, so please take breaks and drink fluids if you are outdoors for long periods. Cooler weather will occur at the coast with a mix of clouds and Sun.
The area of high pressure will move east as low pressure system moves closer to California and Oregon. Models are still struggling with the exact path of this system, but confidence is high that this will bring a troughing pattern over the area, leading to cooler weather. By Tuesday, temperatures will drop about 5 degrees across the deserts and coast, up to 10 degrees for inland valleys. Inland areas will cool again into Wednesday as the system moves close to the region. Mountains and deserts can also expect increasing southwest and west winds near 25-45 MPH. There continues to be slight model differences by the latter part of next week. This will lead to temperatures near to slightly above average with continued dry weather expected.
090900z, Coast/Valleys, Low clouds 800-1200 ft MSL are covering the lowlands of Orange County and up to the foothills of SD County, beginning to reach into the Inland Empire. Vis reduced 0-5SM through eastern elevated inland valleys and increasingly through the Inland Empire (from BR/HZ). By 14z, IFR cig chances around 60% for KONT and 50% for KSBD. Scatter out this morning 16-19Z. Slightly lower clouds 600-1100 ft MSL will develop offshore Sat afternoon and move back into coastal areas after 02Z Sun, developing inland 04-08z Sun. With cigs, VIS 4-6SM at times for elevated coastal sites and inland valleys through the I-15 corridor (e.g. KCRQ, KSEE, ). VIS down to 0-3SM and patchy fog through eastern valleys and in parts of the Inland Empire near gaps in elevated coastal terrain.
Mountains/Deserts, Clear and VFR conditions through early Sunday. Breezy westerly winds with gusts 25-40 kts through mountain gaps and desert slopes 22-06Z. Northwest gusts generally 20-30 kts Sat evening over eastern parts of the Coachella Valley.
No hazardous marine conditions are expected through Wednesday.
Ca, Heat Advisory from 10 AM to 8 PM PDT Monday for San Bernardino and Riverside County Valleys-The Inland Empire.
Extreme Heat Warning from 10 AM Sunday to 8 PM PDT Monday for Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
