Big Bear City, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

352
FXUS66 KSGX 021039
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
239 AM PST Thu Jan 2 2025

.SYNOPSIS...
Fair and warmer weather will prevail today under a ridge of high
pressure and weak offshore flow. Areas of coastal low clouds and
dense fog will occur again this morning along the coast and up to
a few miles inland. Onshore flow will develop Friday into Saturday
morning, with cooler weather and more clouds. High pressure and
offshore flow will return by Saturday afternoon and continue into
early next week for gradual warming. An inside slider may bring
cooler weather with stronger Santa Ana Winds towards the middle
part of next week.

&&

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

Areas of low clouds and fog have developed over the coastal waters
and have locally spread into parts of Orange County. Surface
pressure gradients remain weakly offshore, around -2.5 mb SAN-DAG
and -0.4 mb SAN-IPL. The continuation of weak northeast to
easterly winds will prevent any low clouds and fog from spreading
more than a few miles inland through the morning. Otherwise there
are some thin high clouds moving overhead.

Today will be the warmest day of the weak under offshore flow and
an upper level ridge of high pressure moving over the region.
Highs in the valleys will approach the low 80s, and in general
highs will be around 7-15 degrees above normal away from the
coast. Onshore flow returns on late tonight as the upper ridge
moves inland and an upper level trough approaches the West Coast.
The marine layer remains shallow tonight, though the return of
onshore flow and the development of a very weak eddy will help
spread low clouds and dense fog into the coastal areas by Friday
morning. This change in the pattern will bring several degrees of
cooling west of the mountains on Friday. The main trough axis
passes Friday night, generating gusty southwest to west winds
across the mountains and deserts with local gusts of 30-45 mph on
the wind prone desert slopes and below the passes. The marine
layer will deepen Friday night with the passage of the trough with
low clouds spreading into the western valleys.

We make a quick flip back to weak offshore flow by Saturday
afternoon as surface high pressure builds over the Great Basin
behind the departing trough. High temperatures will actually be
near normal Saturday, but that is short-lived as continued weak
offshore flow and upper ridging to the west bring highs back to
several degrees above normal Sunday and Monday.

The pattern becomes highly amplified and more volatile (low
predictability) beyond Monday. An upper level short wave trough
is progged to drop south through the eastern flank of the ridge
and somewhere into the Southwest on Tuesday. Ensemble solutions
are split 50/50 on the trough digging towards SE California or
further inland towards the Four Corners region. The 00Z
deterministic EC and GFS remain on the western extreme of these
solutions, the EC even bringing some moisture and precipitation
with it, though the precipitation part isn`t supported by the vast
majority of the ensembles, so the forecast remains dry. Around 42
percent of the ensemble space, as well as the deterministic
models, have a closed low developing somewhere in the vicinity on
Wednesday, then closing off and retrograding westward as it begins
to undercut the ridge off the coast, while the remaining
solutions keep it as an open wave and eventually progressing
eastward. While all of these scenarios result in Santa Ana Winds
for at least Tuesday through Thursday of next week, just where the
low tracks will have big implications on the strength of the
winds as well as temperatures. By Tuesday there is a 20% chance of
a moderate Santa Ana event with the potential for further
strengthening on Wednesday and/or if the low takes the more
westward track and remains to our south or southwest. Winds would
be weaker with warmer weather in the more inland/progressive
scenarios.

&&

.AVIATION...
021030Z...Coast...Low clouds and fog will cover most coastal areas
through sunrise. LIFR conditions, with bases 100-300 feet MSL, tops
to 500 feet and vis 0-3SM. Scatter out expected by 16-17Z. Low
clouds with bases around 300-600 feet MSL with areas of vis 1-5SM to
move ashore after 02Z and into western valleys by 12Z Friday.

Otherwise...FEW-SCT clouds at/above 25000 feet MSL and unrestricted
vis today and tonight.

&&

.MARINE...
Patchy dense fog expected this morning with visibility 1 NM or less,
otherwise no hazardous marine conditions are expected through
Monday.

&&

.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...SS
AVIATION/MARINE...MM