Winchester, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

044
FXUS66 KSGX 251635
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
935 AM PDT Fri Apr 25 2025

.SYNOPSIS...
Cool and cloudy with chances of rain and mountain snow through the
weekend. There is a 10% chance of thunderstorms for the mountains
westward Saturday afternoon. Gusty southwest to west winds for
the mountains and deserts this afternoon into Saturday evening
along and below the desert slopes of the mountains. Gradual
warming next week with highs near to slightly above normal.

&&

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

Visible satellite at 9 AM was showing low clouds from the beaches
to the coastal slopes of the mountains. Low cloud coverage was
starting to become less uniform, with the potential for areas of
sunshine to peak out this morning. Low clouds may clear from the
coast but the valleys and mountain slopes may stay mostly cloudy
this afternoon. High temperatures today will be 5 to 15 degrees
below normal. Gusty southwest to west winds will develop over the
mountains and deserts this afternoon and continue through Saturday
night when gusts to 45 to 55 mph will occur on the favored desert
slopes and below the passes.

An upper level low pressure system will dig south and east across
Southern California Saturday. This will bring increased chances of
precipitation, with the highest chances in Orange County, Inland
Empire, and the San Bernardino County mountains. There remains some
timing differences in when the main band of precipitation will move
across the region, with the HRRR showing an earlier passage in the
morning Saturday and our local WRF showing a later passage more in
the late afternoon/early evening. Areas of drizzle or light rain are
possible ahead of the main organized band of precipitation.
Rainfall rates will be mostly light to moderate. HREF chances of
hourly rainfall rates reaching or exceeding 0.25 inches per hour is
15 to 30 percent, with the higher chances on the coastal mountain
slopes. The cold core of the low is expected to move overhead
Saturday afternoon/evening. The cold air combined with some weak
instability will lead to a 10 percent chance of thunderstorms along
and west of the mountains. Rainfall amounts will generally be light
and decrease from north to south, isolated higher amounts are
expected where thunderstorms occur. Some areas in far southern San
Diego County may be left with nothing. Snow levels will fluctuate
between 5000-6000 ft with totals of 1 to 5 inches above 6000 ft,
highest near Mt San Antonio.

Weak troughing lingers across the region Sunday and Monday
maintaining cool weather with a deep marine layer. Highs remain
around 10 to 20 degrees below normal inland on Sunday, then
around 3 to 5 degrees below normal on Monday. Ensembles in good
agreement with an upper ridge trying to nudge in from the west on
Tuesday for more significant warming and highs returning to a
couple degrees above normal, then another weak wave developing and
sweeping southeasterly across the Western US around Wednesday and
Thursday which will moderate temperatures, then another ridge
trying to build in on Friday for minor warming. The marine layer
will become more shallow Tuesday and Wednesday with low clouds
confined to the coastal areas, then deepen again on Thursday -
right in time for May Gray to begin.

&&

.AVIATION...
251600Z....Coasts/Valleys/Coastal Mountain Slopes...Clouds based at
2500-3500 feet MSL with tops near 5500 feet have filled in across
the coasts and valleys this morning with VIS reduced 0-5SM in along
the coastal mountain slopes. Patchy -DZ possible  through 18z with
accompanying lower CIGs near 2000 feet MSL and lower VIS 4-5SM at
times. Clouds start to disperse 18-19z Friday with BKN clouds likely
persisting far inland and against the coastal mountain foothills
through the afternoon. Clouds (with similar bases/tops) increasing
again after 02z Saturday though may be somewhat patchy in the
evening, with a more uniform marine layer expected by about 09z
Saturday. Rainfall chances increase by 06z, increasing through
Saturday afternoon and evening. Rainfall amounts generally expected
to be light.

Mountains/deserts...West winds increase after 20z this afternoon,
gusting 35-45 kts, locally 50 kts, over ridges, through passes and
desert slopes. Strong up/downdrafts are likely, with isolated LLWS
and rotors in lee of mountains, such as vcnty KPSP. Rain chances
develop as early as 06z Saturday, increasing into the afternoon and
evening while gusty winds develop for similar locations with similar
speeds as Friday. Heaviest rain possible in the mountains, and a
thunderstorm threat will exist in the afternoon and evening. Gusty
and erratic winds along with heavy rainfall that may lead to reduced
visibility in any storm.

&&

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

&&

.BEACHES...
Elevated surf of 3 to 6 feet with occasional sets to 7 feet Saturday
through Tuesday, peaking Sunday night and Monday. Strong rip
currents expected.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 2 PM this afternoon to 11 PM PDT Saturday for
     Apple and Lucerne Valleys-San Diego County Deserts-San
     Gorgonio Pass near Banning.

PZ...None.

&&

$$

PUBLIC...CO/SS
AVIATION/MARINE/BEACHES...Zuber