Expires:No;;570070
FXUS66 KSGX 281642
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
842 AM PST Sun Nov 28 2021

.SYNOPSIS...
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
COUNTIES...

.Morning Update...

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 
foothills.

.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 
mountain resorts.

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 
clouds. 

&&

.AVIATION...
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. 

&&

.MARINE...
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 
through Thursday.

&&

.FIRE WEATHER...
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 
farther inland. 

&&

.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,FIRE WEATHER/UPDATE...10/APR
AVIATION/MARINE...CO