Johnstown, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

726
FXUS66 KSGX 020133
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
533 PM PST Sun Nov 1 2026

.SYNOPSIS...
Widespread light rain will continue this morning, becoming more
scattered during the day before tapering off this afternoon and
evening. Dry and warmer for the remainder of the week with highs
near to a few degrees below normal each day.

&&

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


...UPDATED AVIATION DISCUSSION...

As of 10 AM, the warm sector of the storm has pushed east and we
are now advecting relatively colder air aloft. Looking at GFS 18z
forecast soundings, there is some background instability only up to
700 mbs. The axis of the trough to the north is passing east of the
coastal basin, making showers increasingly more isolated this
afternoon through this evening throughout the coastal basin, with
perhaps a few leftover showers in SD County tonight before
completely drying out region-wide overnight into Monday. Given the
relatively shallow instability profiles, any showers that do develop
will be mainly light, with only a few brief showers of moderate
intensity.

Monday will begin with cold morning temperatures, especially in the
inland valleys (40s), high desert (mid/upper 30s) and mountain
valleys (20s/30s). Otherwise, expect sunny skies across the region
with light N/NE offshore flow over the mountains and deserts during
the day, then increasing mid and high level clouds during the
evening as another trough moves north of the region.

With the weak trough moving through Tuesday, some light rain or
drizzle cannot be ruled out for coastal and inland SD County though
the one model (ECMWF ENS) picking up on this possibility seems to
be backing off.

As a result of this trough and another trough Thursday, high
temperatures will remain rather steady Tue-Thu: mid- 70s across
the coastal basin (including the IE), upper 60s in the high
desert, 50s in the mountains and around 80F in the low deserts.

Friday through the weekend, an upper ridge builds over the Western
US. While the intensity of the ridge over SoCal remains uncertain,
the thermal trough likely sets up at the coast or a few miles
inland, increasing high temperatures to the low to mid-80s in the
coastal basin and lower deserts, while the mountains and high
deserts remain cool.

&&

.AVIATION...
011830...Multiple cloud layers 1500 to 10000 ft MSL this morning,
expect frequent cat changes throughout the coastal basin, especially
when -SHRA pass over a site. ISO -SHRA will linger through Sunday
evening in San Diego County and in the mtns but taper off elsewhere
after 22Z. As SHRA tapers off VFR conditions will become more
widespread. Increased W winds around 20 kt near the coast and 40-50
kt on desert mountain slopes, locally into the deserts 20Z Sun-03Z
Mon. Weak NE winds expected overnight into Mon AM.

&&

.MARINE...
Westerly winds increase this afternoon and evening with widespread
gusts 20-25 knots and rough, choppy seas through the outer coastal
waters, and gusts just under 20 knots in the inner coastal waters. A
Small Craft Advisory is in effect for the outer coastal waters
through 9PM today. Weaker winds expected Monday, followed by more
elevated onshore winds Tuesday afternoon and evening, with gusts in
the outer coastal waters potentially exceeding 20 knots.

&&

.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 Monday afternoon for Orange
     County Coastal Areas-San Diego County Coastal Areas.

PZ...Small Craft Advisory until 9 PM PST this evening for Waters from
     San Mateo Point to the Mexican Border Extending 10 to 60 nm
     out including San Clemente Island.


&&

$$

PUBLIC...CO
AVIATION/MARINE...Stewey