128
FXUS66 KSGX 272045
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
145 PM PDT Mon Jul 27 2026

.SYNOPSIS...
A slight cooling trend begins today and continues through
Wednesday, bringing temperatures down to around 5 degrees above
average by midweek. Daytime temperatures rise again for Thursday
through next weekend and we could see the highest temperatures of
this summer so far by Saturday. Some monsoonal moisture aloft
later in the week into the upcoming weekend may also provide a
slight chance of afternoon showers and thunderstorms for our
mountains and deserts.

&&

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

This afternoon...Temperatures range from a few degrees higher to a
few degrees lower than at his time yesterday. There was a weak
coastal eddy last night and low clouds from a shallow marine layer
are persisting at the beaches of San Diego County. High resolution
models indicate that a weak coastal eddy will likely return
tonight.

A shallow marine layer will persist through the forecast period
with night and morning low clouds mostly restricted to the coastal
areas and western portions of the San Diego County valleys.

The large-scale pattern will remain quite stable, with high
pressure centered over the southern Rockies/Desert Southwest and
low pressure centered over the Gulf of Alaska. Through Wednesday,
the high pressure over SoCal will weaken slightly in response to a
vigorous shortwave trough moving inland to our north. The
resulting height falls and weak cyclonic flow aloft will allow the
marine layer to deepen a little and the low clouds to spread a
little farther inland during the nights and mornings. Temperatures
will be generally lower across the region but will be more
noticeable nearer to the coast. By Wednesday, temperatures will
range from a few degrees below normal in some locations west of
the mtns to around 5 degrees above normal in the low deserts.

For Thursday through next weekend...The high pressure center
will shift to the southwest and build over the Desert Southwest.
This will bring significantly warmer conditions to SoCal, we are
likely to see the highest temperatures so far this summer. Models
indicate that Saturday will likely be the hottest day, with
daytime temperatures ranging from 5-10 degrees above normal in the
coastal areas to about 15 degrees above normal in parts of the
inland valleys and deserts. Temperatures will range from the high
70s to the mid 80s near the coast, the low 90s to low triple
digits in inland OC and SD County, low triple digits to about 110
in the IE, 80s to low 90 in the mtns, up to 113 in the high
deserts and up to around 120 in the low deserts. The building high
pressure will also make the marine layer shallower and restrict
the low clouds to the immediate coast during the nights and
mornings. The heat will likely abate slightly for next Monday as
the high pressure weakens. Confidence in the coming high
temperatures is relatively high due to the stable pattern and good
agreement among model solutions.

&&

.AVIATION...
271800Z....Coast/Valleys...Low clouds that filled in earlier this
morning have since cleared out to the coast but will likely
remain stuck to the beaches and immediate coastline through the
afternoon. Any clouds that do clear out through the afternoon will
redevelop and push back ashore after 00z Tuesday, with CIGs expected
at the coastal TAF sites through the night. Bases look to generally
be similar to last night, though perhaps a touch higher, around 1000-
1300ft MSL. Expected a similar inland extent of around 10-15
miles with VIS restrictions limited to coastal mesas and higher
coastal terrain. Low clouds likely scatter back to the coasts around
16-17z Tuesday.

Mountains/Deserts...VFR prevails throughout the day with a few Cu
based AOA 12,000ft possible over the mountains in the afternoon.

&&

.MARINE...
Calm conditions into the early half of next week with waves 3 to 5
feet and afternoon wind gusts near 15 kts or less through Tuesday.
Waves increase in the outer waters mid to late week with waves
expected around 5 to 6 feet.

&&

.BEACHES...
A persistent long-period southwesterly swell (2-3 feet at 17-19
seconds) keeps surf elevated at around 3-5 feet with sets to 6 feet
into Wednesday. A Beach Hazard Statement remains in effect through 5
PM Wednesday for the elevated surf, rip current risk, and concern
for minor tidal overflow.

By Wednesday afternoon/evening, a much higher amplitude swell
associated with Hurricane Genevieve is set to build. Some
uncertainty exists in exactly how strong this swell will be as
it depends on the strength and track of Genevieve, but current
guidance suggests the swell could be around 5 feet, with a period
around 14 seconds. With this, breaking waves of 5-8 feet are
expected, with set up to 9 feet for south-southwest facing
beaches. The swell builds overnight Wednesday into Thursday, with
highest surf expected on Thursday. With this, a High Surf Advisory
has been issued for 5 PM Wednesday through 5 PM Saturday for
dangerous swimming conditions brought about by large breaking waves
and strong rip currents.

In addition to elevated surf, tides are expected to increase to a
height of 6.0 to 6.5 feet MLLW for this evening`s high tide and
continue at that height through most of the week. The combination of
elevated/high surf and tides will likely result in at least minor
tidal overflow during the evening high this evening and
Tuesday evening. More notable coastal flooding is likely for
Wednesday through Friday when the high tides combine with the high
surf brought with Genevieve`s swell later this week. It is worth
noting, that with the effects from this year`s El Nino, observed
tides have been consistently about 0.3-0.5 feet below many baseline
predictions. A Coastal Flood Advisory has been issued for 5 PM
Wednesday through 3AM Saturday for this risk of coastal flooding
associated with the evening high tides.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Wednesday afternoon for Orange
     County Coastal Areas-San Diego County Coastal Areas.

     Heat Advisory until 8 PM PDT this evening for 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 Mountains-San Diego
     County Valleys-Santa Ana Mountains and Foothills.

     Coastal Flood Advisory from 5 PM Wednesday to 3 AM PDT Saturday
     for Orange County Coastal Areas-San Diego County Coastal
     Areas.

     High Surf Advisory from 5 PM Wednesday to 5 PM PDT Saturday for
     Orange County Coastal Areas-San Diego County Coastal Areas.

     Extreme Heat Warning until 8 PM PDT this evening for Apple and
     Lucerne Valleys-Coachella Valley-San Diego County Deserts-
     San Gorgonio Pass near Banning.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE/BEACHES...Munyan

NWS San Diego (SGX) Office