San Diego Forecast Discussion
367
FXUS66 KSGX 190450
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
950 PM PDT Sat Jul 18 2026
.SYNOPSIS...
Near seasonal temperatures through the first half of the upcoming
week with an increase in both high and low temperatures for the
middle to end of next week. Chances for afternoon showers and
thunderstorms will decrease and remain confined to the higher
mountain peaks for much of this week, with the potential for more
widespread shower and thunderstorm activity for the latter half of
next week. The marine layer will remain mostly confined to the
coast, reaching into portions of the valleys at times.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
...UPDATED AVIATION DISCUSSION...
Highs today are forecast to be a few degrees warmer than yesterday
across the area which will bring conditions near to slightly above
average for this time of year. The broad ridge of high pressure over
the western United States has kept the door for moisture open,
indicated by the 1.65 inches of precipitable water on the 12Z KNKX
sounding. There remains chances for showers and thunderstorms over
area mountains this afternoon, but the lack of atmospheric forcing
may be a limiting factor. High resolution model guidance is showing
a few light showers developing over the San Bernardino mountains,
but chances of rainfall rates exceeding 0.50" per hour is less than
10 percent. Shower/thunderstorm chances will decrease into early
next week as upper level ridging shifts east, which will limit the
atmospheric moisture influx.
For the middle of next week, the ridge is forecast to shift south
over Texas and strengthen. There remains some uncertainty in the
ensembles on the position of the high and how far west the ridge
axis will extend. 20 percent of ensemble guidance has the ridge of
high pressure extending far enough west to allow for a moisture
increase. This would be the most favorable pattern for afternoon
showers and thunderstorms.
The position of the ridge will also influence how warm it will get.
Current forecast follows the NBM and has an increase in highs and
lows for the middle to end of the week. The current forecast
supports an increase in moderate HeatRisk west of the mountains and
areas of major HeatRisk in the deserts, mainly due to elevated low
temperatures. Limited overnight cooling will exacerbate impacts from
the heat, especially for vulnerable populations and those without
air conditioning.
&&
.AVIATION...
190430Z....Coast/Valleys...Low clouds based 1000-1400 ft MSL are
filling in off the coast, moving into OC after 07z and filling in up
to 20 miles inland by 11z. VIS restrictions where clouds intersect
terrain and in elevated eastern valley sites like KRNM. Low clouds
scatter out 15-16z with FEW-SCT clouds remaining above 10 kft MSL
and VFR prevailing. Low clouds with similar bases return to the
coast 02-05z Mon.
.Mountains/Deserts...VFR conditions expected through the period with
FEW-SCT mid-level clouds generally AOA 15,000ft MSL. FEW-SCT Cu
based 10-12 kft MSL may develop over the mountain ridgetops Sunday
afternoon, with a small (10%) chance for ISO SHRA/TSRA, most likely
after 21z through 01z Mon. Any storm that develop may produce
lightning, gusty winds, and vis reductions.
&&
.MARINE...
No hazardous marine conditions are expected through Wednesday.
&&
.BEACHES...
High amplitude southerly swell (4-5 ft with a period of 12-13
seconds) will build Sunday, bringing elevated to high surf and
strong rip and longshore currents for Sunday through at least
Tuesday. Highest surf, up to 7-8 ft, will be along south and
southwest-facing beaches. Further details can be found in the High
Surf Advisory. Surf falls a bit Tuesday and into Wednesday before
another southerly swell (4-5 ft with a period of ~14 seconds) brings
another round of elevated to high surf for the end of the week and
into the early weekend. The high risk for strong rip currents will
remain from Sunday through next week.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory from 5 PM Sunday to 11 PM PDT Tuesday for
Orange County Coastal Areas-San Diego County Coastal Areas.
PZ...None.
&&
$$
PUBLIC...PG
AVIATION/MARINE/BEACHES...Westerink
NWS SGX Office Area Forecast Discussion
