Chino Hills, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

337
FXUS66 KSGX 150357
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
857 PM PDT Mon Apr 14 2025

.SYNOPSIS...
Low pressure will keep us cool and breezy this week. Cooler
weather will take hold by Wednesday through Friday as a deep
marine layer impacts the foothills to the coast where morning
drizzle can be expected over the next couple of days. The area of
low pressure will become stronger and push ashore for Wednesday
through Friday, leading to much cooler and windier weather for
inland areas. We may also see a chance of rain by Thursday and
Friday as well. After this passes, warmer and drier weather will
move in next weekend.

&&

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

This evening...The afternoon sounding shows the marine layer a
little deeper than yesterday with a weak inversion. Low clouds are
slow to develop and have not yet begun to increase in coverage,
although high-resolution models continue to show widespread low
clouds extending inland to the coastal slopes by early Tuesday
morning. These models are not initializing very well which casts
some doubt on the model solutions. As a result, confidence is not
very high for widespread low clouds with drizzle west of the
mountains tonight into Tuesday morning.

From previous discussion...
A stronger area of low pressure will begin to form off the coast
tonight into Tuesday morning. This feature will stick around
through the work week, bringing cooler and breezier conditions to
the region. Highs by Tuesday will sink a few degrees cooler than
where they were today.

As the low deepens and moves closer to our area on Wednesday and
Thursday, cooler and breezier weather will take hold. High
temperatures will go down another 5 degrees or so for inland
areas. West winds will strengthen across the mountains and
deserts. In terms of wind speeds, probabilities significantly
change from between 30 and 45 mph wind thresholds, strong winds
are looking more likely to occur. Thursday will be the coolest day
over all across the region with highs in the 60s west of the
mountains into the high desert. Some mountain areas near Big Bear
will stay in the 40s while the lower deserts stay near 80 degrees
or less. Though the exact track of this low is still uncertain, a
chance of showers is in the forecast as model ensembles show light
amounts of precipitation expected for Thursday into Friday.
Confidence is low on exact amounts, but not looking like anything
substantial. We will also have to monitor the chance for
thunderstorms during this time period as well, though current
guidance does not show a strong signal of this occurring.

Another area of low pressure is expected to drop in from the north
by later in the week as well. Depending on the exact track of this
system will see how long the cooler, breezier, and showery weather
sticks around. The latest NBM output shows greater warming and
less wind, aligning with ensemble models showing neutral by the
weekend.

&&

.AVIATION...
150400Z....Coasts/Valleys...Once again, after a day of efficient
clearing, current satellite shows the marine layer is very patchy
with little low clouds across the region and California Bight. Still
expecting cloud coverage to fill in some across the coastal basin
and perhaps into the inland valleys over the next several hours,
though confidence in this is quite low and clouds could very well
stay patchy through the night. If any CIGs do occur, cloud bases
will generally be at 1500-2000ft MSL with VIS restrictions limited
to where clouds intersect higher terrain. Timing out the best
chances for CIGs tonight is between 09-15z. Should more full/uniform
clouds form, they will clear back out from east to west 16-19z
Tuesday morning.

Clearing of these low clouds and DZ will occur at a similar time as
this morning, around 16-19z.

.Mountains/Deserts...Prevailing SCT-BKN clouds based 20,000ft MSL
through Tuesday. Periods of gusty winds through 12z Tuesday in the
mountains and Coachella Valley.

&&

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

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

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