The marine layer will stay thin through the upcoming weekend, where night and morning low clouds will cover the coast each day. High pressure will strengthen across the region through the weekend as well, where areas of mostly moderate to major heat risk will occur across much of Southern California. Slight cooling with an increase in monsoonal moisture will lead to continued humidity, but a limited chance of rainfall in the mountains and deserts.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
The marine layer was not as deep this morning as high pressure over the Desert Southwest begins to squash the layer. Low clouds will continue to cover areas mainly within 10 miles of the coast each night and morning through the weekend. Slightly warmer conditions will be felt today as the high over New Mexico slowly expands. 850mb temps rise more significantly by Friday, so temperatures will warm another 3-5 degrees for most areas. This will bring temperatures near 105 degrees from the Inland Empire into the metropolis of the High Desert, as well as highs in 80s/90s for coastal valleys and mountains.
For the weekend, the area of high pressure peaks in strength on Saturday. This is when we can expect the hottest temperatures. Temperatures will be well into the 90s for valleys and mountains of Orange and San Diego Counties and over 115 degrees across the lower deserts. The high weakens slightly on Sunday, but temperatures only knock down a degree or two. All mountains will remain hot as well. Please severely limit or postpone outdoor recreation in these areas, since temperatures will be well into the 70s and 80s by the mid-morning hours. For those without A/C, make sure to go to air conditioned areas and drink plenty of water. Warm and humid nights in the 60s/70s/80s will lead to less relief from the heat as well.
By early next week, the high weakens subtly and shifts back to the east. This will bring a degree or two of cooling for inland areas each day, but warm temperatures will still remain. Temperatures will stay near to slightly above normal by Wednesday of next week. The high may go into a position that will bring in a subtle return of monsoonal moisture and greater humidity to the region, but rain chances still seem slim.
301800z. Coast/Valleys, Low clouds based around 800-1200 feet MSL will develop and move locally inland again after 01Z. They will not reach as far inland as they were this morning. Vis restrictions 0- 5SM in western valleys. Scatter out Friday by 15-16Z.
Mountains/Deserts, Mostly clear through Friday morning.
No hazardous marine weather is expected through Monday.
A southerly swell from Hurricane Genevieve will continue to generate elevated surf through Friday before diminishing over the weekend. Surf of 4-7 feet with sets up to 9 feet will continue, highest on south facing beaches. This will create conditions hazardous for inexperienced swimmers. In addition, high tides each evening will exceed 6 feet. The combination of high tides and high surf increases the risk of coastal flooding. Further information on all these hazards is found in the Coastal Hazard Message.
Ca, Coastal Flood Advisory until 3 AM PDT Saturday for Orange County Coastal Areas-San Diego County Coastal Areas.
High Surf Advisory until 5 PM PDT Saturday for Orange County Coastal Areas-San Diego County Coastal Areas.
Heat Advisory from 10 AM Friday to 8 PM PDT Sunday for Orange County Coastal Areas-San Diego County Coastal Areas.
Extreme Heat Warning until 8 PM PDT Sunday for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
Extreme Heat Warning from 10 AM Friday to 8 PM PDT Sunday for Orange County Inland Areas-San Diego County Valleys-Santa Ana Mountains and Foothills.
Heat Advisory until 8 PM PDT Sunday for San Bernardino County Mountains.
PZ, None.
