Wildfire in California, June 27 to 29, 2023

Area Forecast Discussion
National Weather Service San Diego CA
156 PM PDT Tue Jun 27 2023

.SYNOPSIS...
A trough of low pressure over the western states will maintain
below average high temperatures through Wednesday with night and
morning coastal low clouds spreading farther into the valleys.
A developing upper ridge over California and Nevada will bring
inland heat this weekend into early next week with temperatures
around 10 degrees above average for the deserts and around 5
degree above average elsewhere. That would put high temperatures
in the lower deserts around 115 over the weekend and around 105 in
the Apple and Lucerne Valleys. The coast will remain mild under a
continued marine layer influence.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Forecast Highlights:

* Heat wave over the deserts this weekend into early next week
* High heat risk developing deserts; Moderate risk inland valleys

The persistent trough over the region will hold through early
Thursday and this will continue to lead to cooler than normal
temps and little day to day changes. However, the trough will exit
to the east with an upper ridge building in from the west and over
California for the upcoming weekend into early next week. The
building ridge will lead to significant warming for inland areas.
In fact, a full fledged heat wave is likely over the deserts this
weekend into at least early next week.

Highs will reach to near 115 over the lower deserts during this
time period and around 105 over the high desert. The heat risk
will be high Saturday through Monday over the deserts. Highs this
weekend will reach well into the 90s to near 100 over the Inland
Empire and in the upper 80s to mid 90s across the inland valley
of San Diego County/moderate heat risk. However, the coast will
stay moderated by a shallow marine layer.

Look for abundant sunshine throughout the week. Clouds will lie
along the coast at night and in the morning. The marine layer
slowly deepens through Wednesday before becoming shallower
towards the end of the week.

After the intense desert heat Saturday through Monday, the
formidable heat wave could tame July 4-6 per especially EPS. A
downward trend in temps is most likely during this period.

&&

.AVIATION...
272030Z...Coast/Valleys...Mostly clear skies this afternoon. Low
clouds will begin to move inland after 02Z. Bases of 1000-1800 ft
MSL expected. Areas of vis 3-5 SM in BR/HZ with local terrain
obscurations. Low clouds expected to spread 20 miles from the coast
by 10Z Wed. SCT conditions expected 17-19Z Wed.

Mountains/Deserts...Mostly clear skies with unrestricted vis will
continue through tonight. Areas of west surface winds 15-30 kt with
gusts 40-50 kt will occur again 23Z today-13Z Wed, mainly from the
mountain crests through the desert slopes and locally into the
deserts. Winds will increase again after 18Z Wed, with similar
speeds.

&&

.MARINE...
West to northwest winds will locally gust around 20 kt over the
outer coastal waters (30-60 NM) each afternoon and evening through
tomorrow.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

PUBLIC...Gregoria
AVIATION/MARINE...CO