The early part of the month brought a large area of high pressure and a shallow marine layer, which led to widespread dense fog for the coast and western valleys.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SGX wrote it up.
The early part of the month brought a large area of high pressure and a shallow marine layer, which led to widespread dense fog for the coast and western valleys.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before the first event at Dec 1, 8:30 PM PST, 3 hours 30 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
830 PM PST Wed Dec 1 2021
.SYNOPSIS...
Areas of dense fog will impact the coastal and western valley areas
tonight through Thursday morning. While Thursday and Friday will be
a couple of warm days, they won't be quite as warm as Wednesday.
Night and morning low clouds and fog will become a little more
widespread Friday and Saturday. Santa Ana winds will bring warmer
weather and gusty offshore winds to the mountains and
foothills Sunday and Monday.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EVENING UPDATE: Fog returned to the coastal zones this evening and
had spread into some of the San Diego County western valleys at 8
PM. Here were some visibilities:
Santa Ana.......1/8 mile
Newport Beach...1/4 mile
Long Beach......1/4 mile
Fallbrook.......1/4 mile
Brown Field.....1/2 mile
Carlsbad........2.5 miles
San Diego.......3 miles.
A Dense Fog Advisory is in effect for the San Diego and Orange
County coastal and valley zones through 10 AM Thursday. Dense fog is
likely to impact the morning commute in these areas.
*From Previous Discussion*
The ridge of high pressure that is centered across the western US
and a low pressure system to the southwest approaching Baja
California will begin to move east today. Southern California will
become more influenced by the low, increasing onshore flow starting
Thursday. Onshore flow will prevail through Saturday, spreading
cooler conditions inland and bringing coastal low clouds and fog
into portions of the valleys through Saturday.
The pattern changes for Sunday and Monday, bringing another round of
Santa Ana winds to Southern California. Gusty northeast to east
winds, above average temperatures, and dry conditions expected.
ECMWF global ensemble members on the 12Z run Wednesday are trending
weaker in wind speed for Sunday and Monday compared to the 00Z run
Wednesday. Global ensembles continue to show a significant warm up
on Sunday and Monday. Early next week, the pattern shifts again as a
longwave trough pushes into the Pacific Northwest Monday, with the
influences reaching Southern California by Tuesday. Winds will turn
back onshore and temperatures will fall noticeably for Tuesday.
&&
.AVIATION...
020355Z...Coast/Valleys...Low clouds with bases 200-700 ft MSL and
vis 3SM or less in BR/FG continuing to fill in along the coast and
up to 15 mi inland tonight. Areas of vis below 1 SM likely at times
in Orange County and over the higher coastal terrain/coastal mesas
of San Diego county through 15Z Thu. Clouds clearing to the coast 16-
18Z though vis of 3-6 SM in HZ likely to prevail through much of the
afternoon. Areas of low clouds with bases closer to 500-800 ft MSL
spreading back inland Thu evening.
Mountains/Deserts...A few high clouds at/above 20,000 ft MSL and
unrestricted vis through Thursday evening.
&&
.MARINE...
Areas of dense fog will continue tonight into mid-morning Thursday
with visibility below 1 NM. Patchy fog may redevelop Thursday
evening into Friday morning. Otherwise, no hazardous marine weather
conditions are expected through Monday.
&&
.BEACHES...
Morning king tides near 7 feet Friday through Sunday could lead to
minor coastal flooding, mainly for low lying beach parking lots and
boardwalks. Surf will remain relatively small.
&&
.FIRE WEATHER...
Weak Santa Ana winds will continue diminish through the afternoon.
Very dry conditions will continue this afternoon with minimum
relative humidity values 10-20%, leading to elevated fire weather
conditions across the mountains and valleys.
Winds will turn onshore on Thursday, with cooler temperatures and
higher relative humidity values spreading inland through Saturday.
Santa Ana winds will redevelop for the second half of the weekend
into early next week, with elevated to near critical fire weather
conditions possible for the mountains, valleys and inland Orange
County.
&&
.SKYWARN...
Skywarn activation will not be needed Thursday.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory through 10 AM Thursday for
Orange County Coastal Areas-Orange County Inland Areas-
San Diego County Coastal Areas-San Diego County Valleys.
PZ...NONE.
&&
EVENING UPDATE: Moede
PUBLIC/FIRE WEATHER...CO
AVIATION/MARINE...SSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
644 PM PST WED DEC 1 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0634 PM DENSE FOG SANTA ANA 33.67N 117.87W
12/01/2021 ORANGE CA AWOS
ONE QUARTER MILE VISIBILITY AT JOHN WAYNE
AIRPORT.
&&
MOEDEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
706 PM PST WED DEC 1 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0655 PM DENSE FOG FALLBROOK 33.35N 117.25W
12/01/2021 SAN DIEGO CA AWOS
ZERO VISIBILITY AT FALLBROOK AIRPARK.
&&
MOEDEThe national radar mosaic for the moment the first event began.
3 dense fog. Local standard time, as filed.
Zero visibility at Fallbrook Airpark AWOS.
One quarter mile visibility reported at times at Los Alomitos Airfield and John Wayne ASOS sites.
Storm spotter reports going on a walk at 7:30 under clear skies. By 8:15 the fog rolled up the hill from the ocean completely obscuring the sky. Within minutes, visibility was reduced to less than one block. There were sections of less than 100 yard visibility measured by using known distances between houses, etc.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, December 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 996227, 996228, 996226.