Wildfire in California, September 1 to 5, 2022

Area Forecast Discussion
National Weather Service San Diego CA
919 PM PDT Wed Aug 31 2022

.SYNOPSIS...
A heat wave will continue into early next week. The return of
some monsoonal moisture is expected to bring a slight chance of
thunderstorms mainly to the mountains Friday into next week. Skies
will be mostly clear, with a few high clouds and periods of
patchy low clouds near the coast.

&&

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

.Evening Update...

It was quite a hot day out there today, with many locations
breaking or tying their daily temperature records. Anaheim (at 106
degrees) not only broke their high temperature record for the
day, but also broke their all-time high temperature record for the
month of August. The previous all-time August record was 105
degrees set back on August 18, 2020.

Temperatures on Thursday will more or less be the same as today
west of the mountains. Increasing moisture in the lower deserts
may shave a few degrees off their high temperature on Thursday
compared to today, but it will surely still feel just as hot as
today due to the increased humidity.

Slight cooling is expected west of the mountains on Friday due to
the development of a coastal eddy, but temperatures will still
remain quite warm. Temperatures will bump right back up on
Saturday as that coastal eddy weakens. Sunday and Monday still
look to be the hottest days during this heat wave.

The forecast remains on track, with Excessive Heat Warnings in
place for all areas. No changes were made to the forecast this
evening. See the previous discussion below for more details on the
heat wave and thunderstorm potential.

.Previous Discussion issued at 1:34PM...

The heat wave is still on track to continue into next week. Coastal
temperatures are expected to be a few degrees cooler Thursday and
Friday with the development of a coastal eddy. With the eddy, low
cloud coverage is expected to increase Friday morning. A low level
moisture influx into the lower deserts will act to moderate
temperatures there Thursday and Friday. That being said, highs there
will be mostly above 108 degrees. Even with the slightly cooler
temperatures, highs will still be 5 to 10 degrees above average
across the forecast area.

Saturday through early next week the high pressure over the Great
Basin remains in place and is expected to strengthen for Saturday
and Sunday. High temperatures Saturday through Monday will be 15 to
20 degrees warmer than average for the coast and western valleys, 10
to 15 degrees above average for the Inland Empire and eastern
valleys in San Diego, 7 to 10 degrees above average in the
mountains, and 5 to 10 degrees above average in the deserts.
Excessive heat may continue into Tuesday, with gradual cooling
expected for the end of next week. In addition to the daytime heat,
nights will be quite warm as well with low temperatures for the
coast and valleys mostly in the 70s to around 80 with the warmer
lows near the coastal foothills. In the lower deserts, low
temperatures will mostly be in the mid 80s to lower 90s.

At the coast, the potential development of a coastal eddy late in
the weekend is adding some uncertainty to the high temperature
forecast. NBM guidance for coastal areas is showing an 8 degree
temperature spread between the cooler and warmer high temperature
solutions. That uncertainty in high temperatures continues into
Tuesday for coastal areas.

Mid level moisture and easterly flow could bring more afternoon
clouds to the mountains beginning on Thursday with small chances for
an isolated shower or thunderstorm in the higher mountains during
the afternoon and early evening. Slight chances of thunderstorms in
the mountains each afternoon and early evening, possibly drifting
into the adjacent inland valleys will continue into next week.

&&

.AVIATION...
010400Z...FEW with bases near 1000 FT MSL will be possible late
tonight near the immediate coast, though cigs are not expected to
develop. On Friday, SCT Cu possible in the mountains, with bases
around 10,000 FT MSL. Otherwise...mostly clear through Thursday.

&&

.MARINE...
No hazardous marine weather is expected through Monday.

&&&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 8 PM PDT Monday for Apple and
     Lucerne Valleys-Coachella Valley-Orange County Coastal
     Areas-Orange County Inland Areas-Riverside County Mountains-
     San Bernardino County Mountains-San Bernardino and
     Riverside County Valleys-The Inland Empire-San Diego County
     Coastal Areas-San Diego County Deserts-San Diego County
     Mountains-San Diego County Valleys-San Gorgonio Pass Near
     Banning-Santa Ana Mountains and Foothills.

PZ...None.

&&

PUBLIC...Connolly(update)/CO(previous discussion)
AVIATION/MARINE...Brotherton