*Annual Rainfall is based on the California Water Year,|
which runs from October 1 through September 30.
FXUS66 KSGX 281642
Area Forecast Discussion
National Weather Service San Diego CA
842 AM PST Sun Nov 28 2021
High pressure aloft, and prevailing weak offshore flow, will bring
fair and warm days, with cool nights all week. A weak trough along
the Southern California coast will keep some patchy low clouds and
fog over the coastal waters and nearshore, otherwise skies will be
clear. A cooling trend is expected to begin next weekend as high
pressure retreats and the marine layer rebuilds inland.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
As is typical with weak offshore flow patterns, another cool
morning occurred across the region. For inland areas, it all
depends on whether you're located in hilly terrain or in a deeper
valley. Some places saw temperature swings near 30 degrees within
a couple miles this morning due to the differences in terrain,
where wind sheltered valleys were much colder! This pattern is
also keeping clouds far offshore. Temperatures will warm rapidly
this morning, with many areas getting into the 70s and 80s by the
afternoon, while the mountains will stick mainly into the 60s to
near 70 degrees with lots of sunshine. Slight warming can be
expected through the middle of the week, with Santa Ana winds
becoming strongest on Wednesday across the mountains and
.Previous Forecast (As of 210 AM Sunday)...
Expect another sunny and mild day over coastal areas, and warm
inland with highs in the valleys in the 80s, and 60s at the
High pressure aloft, squarely over California today will weaken
slightly through Monday, and then rebuild along 40N latitude
midweek, with a weak upper low center just off the Baja coast. This
is a very stable pattern, locking the Polar Westerlies well to the
north. It won't break down fully until next week if the current
suite of global models has their way. There is at least a consensus
between deterministic GFS/ECMWF 00Z model runs now that the ridge
will retrograde westward, allowing a bulge southward in the
Westerlies. This adjustment will be critical for our weather going
forward. Based on the various ensemble members of these models, the
critical timeframe for this adjustment is early next week (Sun/Mon)
when solution spread jumps.
Based on the latest Control runs, the developing dip in the
Westerlies next week will occur too far inland to result in any
meaningful precipitation over SoCal. There has been a corresponding
shift to drier in the ensemble solutions as well next week.
With all that in mind, look for little change in our current weather
pattern. Continued fair and dry all week with warm days (above
average temperatures) and chilly nights. There will be an overall
weakening of the ridge aloft so, perhaps a better chance of some
patchy low clouds and fog visiting the coast over the next few days.
There will be a better chance for the marine layer to make
meaningful progress inland late in the week as the ridge aloft
weakens, which should be accompanied by more night and morning low
281615Z...Mostly clear skies with unrestricted vis today. Patchy fog
over the coastal waters could impact the beaches and a few miles
inland late tonight into Monday morning. If any cigs develop bases
expected to be 300-500 ft MSL with vis lowering to 3SM or less. It
is unlikely cigs and vis restrictions would impact coastal airports.
Patchy, locally dense fog will continue over the coastal waters
tonight. Visibility below 1 NM possible at times. Patchy fog will be
possible at times mainly during the nights and mornings through
Tuesday. Otherwise, no hazardous marine conditions are expected
Weak Santa Ana conditions will prevail this week. Local northeast
winds of 15-25 MPH in wind-favored areas will continue at times,
then increase around midweek to around 20-30 MPH (stronger gusts
below the passes). Near the coast, a shallow marine layer is
bringing some increase in humidity. This will oscillate along the
immediate coast without penetrating much inland until late in the
week. Given the dry conditions and above average daytime
temperatures, fire weather conditions will be somewhat elevated each
day, especially in the offshore, wind-prone areas along the coastal
slopes and foothills.
Late in the week, fire weather conditions will ease west of the
mountains as onshore flow pushes marine air and higher humidity
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.