National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KSGX 181951
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1251 PM PDT Thu Apr 18 2024

.SYNOPSIS...
A weak trough of low pressure will continue to move over the area,
bringing cooler temperatures, clouds, and breezy conditions. Low
clouds and fog will occur each morning as well. High pressure will
move into the area for the weekend, bringing warmer and sunnier
weather. A trough off the Pacific will move ashore next week,
brining cooler and windier weather to Southern California.

&&

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

.SHORT TERM (Today through Saturday)...
A weak trough draped across the eastern Pacific and SoCal is
leading to cloudier and cooler conditions today across the region.
GOES imagery depicts higher clouds beginning to thin from west to
east at this hour, where a better mix of clouds and sun will occur
this afternoon and evening. The marine layer will deepen further
as well, prompting low clouds and fog to fill much of the coastal
basin by Friday and Saturday mornings.

Southwest/west winds will begin to increase across mountains and
deserts later this afternoon, with mountain passes and deserts
seeing gusts 25-45 MPH. As the pressure gradient tightens as the
system passes over SoCal on Friday afternoon and night, winds will
become a bit stronger and more widespread with gusts 35-55 MPH
expected. High temperatures will also cool slightly more than
today with highs in the 60s and 70s for many, while the 90s hang
on in the lower deserts.

A weak ridge of high pressure will move into the area on Saturday,
leading to slightly warmer temperatures and calmer winds.

&&

.LONG TERM (Sunday through Mid-Next Week)...
The ridge will peak in intensity on Sunday, leading to the
warmest day of the next week for most. Though probabilities for
triple digit heat have slightly decreased, a modest (35-55%)
chance still remains for areas like Palm Springs to see 100
degrees by Sunday. Heat risk will also reach into the moderate
category for the lower desert regions, so stay hydrated and seek
shade if outdoors for long periods. The ridge will not stick
around for long, weakening by Monday as a trough enters the area
through next week.

Temperatures will still be well into the 90s for the lower
deserts Monday, but start to cool west of the mountains as
onshore flow increases. As it does so, winds will pick up across
the mountains and deserts Monday. As the trough draws near,
temperatures will continue to scale back with more marine layer
clouds and fog west of the mountains. Winds will continue to be
gusty as well through at least Wednesday, so hi-res guidance was
incorporated to increase winds during this period. Though
confidence on wind speeds remain low, many ensembles from the
ECMWF and GFS have winds nearing 40 MPH across the deserts.

The trough does have the potential to become a stronger closed
low type of system, so we will keep an eye on if it will also
bring any precipitation with it in the coming days.

&&

.AVIATION...
181930Z...Coast/Valleys...Low clouds and fog will continue with
bases 500-900 feet MSL and tops to 1200 feet. Vis 0-5SM over mesas
and higher coastal terrain. Low clouds to push ashore after
02-03Z this evening and into western valleys after 10Z Friday.
Bases should be around 1200-1600 feet MSL with local vis
reductions along inland extent. Low clouds should scatter out
between 19 and 21z, though clearing at the immediate coast may
only be brief or intermittent in spots.

Otherwise...BKN high clouds at/above 20000 feet MSL will continue
through 23Z, SCT thereafter. VIS will remain unrestricted.

&&

.MARINE...
No hazardous marine conditions are expected through Monday.

&&

.BEACHES...
A long-period swell from the Southern Hemisphere will continue to
bring breaking wave sets up to 7 feet this afternoon, especially on
south-facing beaches in Orange County, before gradually subsiding
thereafter. This will generate a high rip current risk.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement until 8 PM PDT this evening for Orange
     County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE...Adams