The peak of the heat will occur through the weekend as an area of high pressure stays over the region. The weather system will weaken and push slowly eastward through the upcoming week, bringing a slight cool down and increasing winds across the mountains and the deserts. There will be increasing monsoonal moisture as well, but chances for rainfall in the mountains continues to look limited by the end of next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
The thin marine layer this morning allowed for only patchy clouds near the coast and far western valleys. The strength of the high pressure aloft is creating a larger inversion, where clouds may stick to the coast through the afternoon at times. This high has peaked near 600 dm, leading to the hottest temperatures of this heat wave. Temperatures were slightly increased for the afternoon based on yesterday's heating. High temperatures will be well into the 90s for coastal valleys, near 100-110 across the Inland Empire and San Diego foothills, and upper 80s and 90s in the mountain areas. The high pressure system begins to weaken on Sunday, allowing for a few degrees of cooling. With the hot weather this weekend, heat risk will be moderate to high, so please take proper precautions if going outdoors. Outdoor recreation is discouraged during the daytime!
The high weakens slowly, then stabilizes by Monday into the upcoming week. This will bring temperatures near to 5 degrees above normal with minimal day to day changes. Temperatures in the 90s to near 100 in the Inland Empire can be expected, with lower deserts seeing a slower cooldown with highs remaining over 110 degrees. Highs will be in the 80s for coastal valleys. Marine layer clouds will form each night and morning within 15 miles of the coast next week.
The high pressure system will eventually move eastward by Wednesday into the latter part of next week, bringing in greater monsoonal moisture. Pwat's rise over an inch in the mountain and desert regions, but rainfall does not seem likely over the mountains by Thursday and Friday with chances near 15% or less. Temperatures will stay relatively unchanged from the beginning of the week, with increased humidity across the entire region.
020100z. Coasts, Areas of low clouds based around 700-1000 feet MSL will gradually form after 06Z and overnight, but in somewhat random and intermittent fashion. Local vis 3-5SM on higher coastal terrain. Any cigs Sunday morning will scatter out by 16Z Sunday. Similarly patchy clouds with similar bases expected to again impact coastal areas after 06Z Mon.
.Valleys/Mountains/Deserts, Mostly clear and VFR conditions to continue through Sunday afternoon.
No hazardous marine conditions are expected through Wednesday.
Ca, Heat Advisory until 8 PM PDT Sunday for Orange County Coastal Areas-San Bernardino County Mountains-San Diego County Coastal Areas.
Extreme Heat Warning until 8 PM PDT Sunday for Apple and Lucerne Valleys-Orange County Inland Areas-Riverside County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains-San Diego County Valleys-Santa Ana Mountains and Foothills.
Extreme Heat Warning until 8 PM PDT Monday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
