Lake Forest, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

214
FXUS66 KSGX 062018
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
118 PM PDT Mon Apr 6 2026

.SYNOPSIS...
Widespread mid and high clouds today will clear from the west
overnight. Low clouds and fog will become more widespread each
night and morning through the week as the marine layer deepens.
Temperatures will fluctuate a few degrees each day through mid-
week, remaining around 5 to 10 degrees above normal. Much cooler
with gusty onshore winds and chances of precipitation for Friday
through the weekend.

&&

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

An upper level disturbance brought widespread mid and high clouds
to the region today some of which produced rain. Most of the rain
evaporated in the dry sub-cloud layer before reaching the ground,
although a trace of rain reached the ground in a few places. The
disturbance also weakened the marine layer inversion and mixed out
the boundary layer so there has been no low clouds or fog to
speak of today.

The disturbance will move east tonight taking the mid and high
clouds with it and a transient ridge of high pressure will
traverse the region through Wednesday. This will allow the marine
layer to return, with low clouds and fog in the coastal areas and
western valleys each night and morning. There will be only minor
day-to-day variations in temperature, with daytime highs remaining
about 5-10 degrees above normal each day.

Numerical models are in pretty good agreement through Friday with
respect to the evolution of the synoptic pattern. A vigorous low
pressure system, with a closed low at 500 mb, will likely impact
the region from Thursday through the weekend. Temperatures will
begin to lower, clouds increase and onshore flow strengthen on
Thursday. Daytime high temperatures will be near or a few degrees
above seasonal averages and westerly winds could be gusting to
35-40 mph in the mtns and on adjacent desert slopes.

For Friday through the weekend...model solutions begin to diverge
and there is increasing uncertainty in the details of the
forecast. In general, clouds will continue to increase through
Saturday and temperatures will continue to trend lower. Sunday
will likely be the coolest day, with high temperatures near or as
much as 10-15 degrees below seasonal averages. This low pressure
system will likely be vigorous enough to bring chances for
widespread measurable rainfall and some mountain snow. Saturday
will be the day with the best chances for precip and the greatest
accumulations. Snow levels will start out above 7000 ft before
lowering to around 6500 ft on Sunday as the precipitation begins
to taper off. The National Blend of Models currently shows a 65%
chance of 0.25 or more in the mountains, a 45%-55% chance in the
valleys and coastal areas, about a 25% chance in the high deserts
and a 10% or less chance in the lower deserts.

The low pressure system moves east by late Sunday and weak upper
level troughing remains over the Western US into Monday,
maintaining cool weather with highs near or a few degrees below
seasonal averages.


&&

.AVIATION...
061730Z...BKN-OVC high clouds above 15000 feet MSL through 18-20Z,
becoming mostly clear thereafter. Some of these mid level clouds
have become convective enough to produce -SHRA/Virga. Coastal low
clouds more likely after 05Z tonight along the immediate coastlines,
and then spreading into some of the inland valleys by 09-11Z
Tuesday. Bases will be similar to last night, although a little more
elevated at around 1000-1500 ft MSL along the coastal areas, then
falling to around 500 ft further inland with better coverage
expected further inland tonight, with patchy fog being possible for
portions of the inland areas. These clouds should begin to scatter
from east to west by tomorrow morning by 15-17Z Tuesday.

&&

.MARINE...
No hazardous marine conditions are expected through Friday. Wind
gusts in the outer waters could exceed 20 knots Wednesday night.

&&

.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...Stewey