Strengthening high pressure aloft into the weekend will bring very hot days for inland areas and warm humid nights except for the highest elevations in the mountains for Thursday into the weekend with record overnight warmth for many areas for Friday and Saturday. Monday and Tuesday will cool a few degrees each day, but high pressure as strong or stronger than late this week could return near the end of next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
(today through Friday), High pressure aloft will expand westward and strengthen across southern California into the weekend. High temperatures for coastal areas may cool a few degrees today while high temperatures in the mountains and Inland Empire warm 5 to 10 degrees. For Thursday, high temperatures will warm another 5 to locally 10 degrees for the valleys, the coastal slopes of the mountains, and inland Orange County.
High temperatures on Thursday and Friday will be around 5 degrees above average near the coast and around 10 degrees above average for inland areas with high temperatures ranging from around 80 near the coast to the upper 90s to 110 for the Inland Empire with 112 to 118 for the lower deserts. Low temperatures will be quite warm as well for Friday and Saturday, mostly in the 70s for the coast and valleys. in the upper 80s to upper 90s for the lower deserts, and in the mid 70s to mid 80s for the Apple and Lucerne Valleys. Most of the records that are tied or broken will likely be from warm overnight low temperatures with the days for the largest number of such records to be tied or broken on Friday and Saturday.
The marine layer will remain around 1500 feet deep with night and morning coastal low clouds spreading locally into the far western valleys at times late each night.
Precipitable water values will continue to decrease into tonight, increase for Thursday and Friday, then decrease into the middle of next week. On Tuesday afternoon, there were some clouds over the San Bernardino Mountains but the remaining mountains were mostly clear. With the increase in moisture for Thursday and Friday, there could be an isolated shower over the San Bernardino Mountains on Thursday afternoon with a slight chance of showers for the mountains in San Bernardino and Riverside Counties for Friday afternoon.
(Saturday through Tuesday), The beaches won't be as hot during the day as inland areas, but nights will still be warm and humid with low temperatures mostly in the lower 70s. The higher elevations in the mountains, mostly above 7000 feet, will be drier with cooler nights and days not as hot. Otherwise, most areas through the weekend will have hot days and warm humid nights through the weekend with only a few degrees of cooling for Monday and again on Tuesday of next week.
By the end of next week, high pressure as strong or stronger as the high pressure aloft for late this week could return.
221000z. Coast/Valleys, Low clouds will continue to fill in areas within 15 miles over the coast this morning. Patchy vis reductions (3-5SM) expected for elevated coastal terrain and western valleys. Clouds scatter back to the coast by 18-19Z, though there is a 50-60% chance for BKN cigs along the immediate SD County coast through the afternoon.
A weak coastal eddy may help to spin up low clouds after 06Z Thu. across San Diego County with bases near 1,000 ft MSL; increasing confidence cigs not reaching KSNA.
Mountains/Deserts, Mostly clear with VFR conditions prevailing through the TAF period.
Northwesterly winds with gusts 20-25 kts in the outer waters near San Clemente Island expected both Wednesday and Thursday afternoons. Additionally, a mixed swell will cause steep and choppy seas up to 6 feet on Thursday and Friday, especially in the outer waters.
Ca, Heat Advisory from 10 AM Thursday to 6 PM PDT Saturday for San Diego County Coastal Areas.
Extreme Heat Warning from 10 AM this morning to 8 PM PDT Monday for Coachella Valley-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
Heat Advisory from 10 AM this morning to 8 PM PDT Monday for Orange County Inland Areas-Riverside County Mountains-San Bernardino County Mountains-San Diego County Valleys-Santa Ana Mountains and Foothills.
Extreme Heat Warning from 10 AM Thursday to 8 PM PDT Monday for Apple and Lucerne Valleys.
PZ, Small Craft Advisory from noon today to 9 PM PDT Thursday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
