The first in a series of Winter storms hit Southwestern California. 18 inches).
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 LOX wrote it up.
The first in a series of Winter storms hit Southwestern California. This storm produced heavy rainfall with totals ranging between 2 and 8 inches (with San Marcos Pass topping out at 8.18 inches). In the mountains, significant snow fell above 5000 feet. Six to twelve inches of snow fell above 6000 feet with 1 to 3 inches down to 4000 feet. Along with the rain and snow, strong and gusty southerly winds developing with peak gusts up to 89 MPH. Numerous reports of nuisance roadway flooding as well as downed trees were reported.
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 Los Angeles, CA wrote its last area forecast discussion before the first event at Dec 13, 5:19 PM PST, 31 minutes earlier.
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
519 PM PST Mon Dec 13 2021
.SYNOPSIS...13/153 PM.
A strong storm system will slowly move over the region through
Tuesday. Rain, heavy at times, and high elevation snow will
develop later today and will continue through Tuesday. Gusty and
potentially damaging winds are expected over the area through
Tuesday. Another weak storm system will affect the region Thursday
followed by dry weather next weekend.
&&
.SHORT TERM (TDY-THU)...13/149 PM.
Overall, 12Z models in good synoptic agreement through the short
term period. Main features will be a strong upper low moving
across the area tonight/Tuesday, followed by a much weaker low
moving across the West Coast on Thursday.
Forecast-wise, main focus continues to be on a very strong storm,
moving across the area tonight and Tuesday. Overall, 12Z models
continue to advertise the same story, leading to a high confidence
forecast. Moderate/heavy rain (associated with a cold front) will
impact SLO/SBA this afternoon and tonight with the rain pushing
south and east tonight and Tuesday with moderate/heavy rain
across LA county on Tuesday. Behind the front, there will be some
lingering showers Tuesday night, mainly across the northern
slopes. Rainfall totals with this storm still look to range from
1-3 inches for coasts/valleys and 3-6 inches across the foothills
and mountains. Locally higher amounts will be possible in the more
favored upslope areas through Tuesday afternoon. Hourly rainfall
rates generally 0.33 to 0.66 per hour are expected with local
rates up to 1.00 per hour possible. With a strong jet moving
across the area on Tuesday, there will be a slight chance of
thunderstorms all areas during the day on Tuesday which could
enhance rainfall rates. Due to the potential for significant
rainfall and rainfall rates, a FLASH FLOOD WATCH has been issued
for burn scars in SBA and LA counties. Please see LAXFFALOX for
the latest details on timing/location.
With this system, snow levels will remain quite high through
Tuesday (above 6000 feet) as the heaviest rain moves through. So,
resort levels can expect anywhere from 1 to 3 feet of snowfall.
For lower elevations, snow levels will not drop until late Tuesday
afternoon/night when the rain will be tapering. So, snowfall
totals at lower elevations will be much less. However, there is a
possibility of 1-3 inches of snowfall Tuesday night down to the
Grapevine level. Please see LAXWSWLOX for the latest details on
WINTER STORM WARNINGs for the LA and Ventura mountains.
Finally, the third main hazard with this storm will be strong and
gusty winds. Gusty southerly wind will continue to increase
tonight and Tuesday across the area. Across the local mountains as
well as the interior valleys of SLO/SBA counties and Antelope
Valley, warning level wind gusts are likely and a HIGH WIND
WARNING remains in effect for these areas. Elsewhere, advisory
level wind gusts are likely and WIND ADVISORIES remain in effect
for all other areas. Please see LAXNPWLOX for the latest details
on the various wind products.
After a cool and dry Wednesday, another system is expected to
impact the area on Thursday. However, this system on Thursday is
much weaker than the current system. Initial rainfall estimates
with this system are for 0.25 inches or less with the "heaviest:
rainfall across the Central Coast.
.LONG TERM (FRI-MON)...13/150 PM.
For the extended, models exhibit good synoptic agreement through
the period. At upper levels, ridge will build in from the west
through the weekend. Near the surface, varying amounts of offshore
flow will develop.
Forecast-wise, this pattern will lead to dry conditions across the
area through the weekend. There may be some scattered high clouds
from time-to-time, but offshore flow will keep any stratus from
developing. So, mostly clear conditions can be expected. There
will be some gusty northeast winds through the period, but winds
are generally expected to remain below advisory levels. Despite
the ridge overhead and the offshore surface flow, temperatures,
albeit warmer, will still be a few degrees below seasonal normals.
&&
.AVIATION...14/0115Z.
At 2352Z at KLAX, there was a deep moist layer to 6100 feet.
Low confidence in all TAFs. Timing of cig, wind, and wx changes
could be off by 3 hours. Increasingly adverse conditions are
expected during the period. Ceilings will gradually lower tonight
into Tuesday morning with IFR ceilings and visibility quite
possible during the peak of the storm Tuesday morning. Winds will
be a big concern with this storm as the coastal sites could see
wind gusts to 40 knots. There is a slight chance of thunderstorms
late tonight and Tuesday.
KLAX..Low confidence in TAF. Steady rain and MVFR cig/vis could
arrive as early as 14/00Z. High confidence in an east component of
10 kts or greater through 19Z, and high confidence in south
component of 20 kts or greater from 04Z to 21Z. The strength of
the surface winds will be capable of generating LLWS and UDDFS.
KBUR...Low confidence in TAF. Steady rain and MVFR cig/vis could
arrive as early as 14/00Z. The strength of the winds will be
capable of generating LLWS and UDDFS.
&&
.MARINE...13/1049 AM.
For the Outer Waters, moderate confidence in current forecast.
Gusty winds will start out southerly, reaching Gale Force sometime
this morning over northern portions of the waters. Winds shift to
a northwest direction Tuesday afternoon and night. Gale force
winds should linger over southern portions of the outer waters
into Tuesday evening. The current Gale Warning has been extended
into Tuesday night for the waters south of the Channel Islands.
SCA level seas may linger into Thursday.
For the Inner Waters north of Point Sal, moderate confidence in
current forecast. High confidence in SCA level wind and seas
remaining through Tuesday, with Gale force winds likely today and
tonight. By Wednesday, high confidence in winds returning to below
SCA levels, whereas SCA level waves may linger into Thursday.
For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. High confidence in winds
increasing to SCA levels today and remaining through Tuesday.
Gale force winds are likely this evening through Tuesday evening.
By Thursday, high confidence in winds and seas returning to below
SCA levels.
A storm system approaching from the northwest will bring
dangerous sea conditions with widespread gale force winds, seas up
to 12 to 15 feet, and steep waves, especially along the Central
Coast. There will also be moderate to heavy rain and the
potential for thunderstorms. Refer to the Marine Weather Statement
for more information. Mariners should remain in safe harbor
during these dangerous conditions.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 10 PM PST Tuesday for
zones 34-35. (See LAXCFWLOX).
Wind Advisory in effect until 6 AM PST Tuesday for zones
34>36. (See LAXNPWLOX).
High Wind Warning in effect until noon PST Tuesday for zones
37-38-51-52. (See LAXNPWLOX).
Wind Advisory in effect until 11 AM PST Tuesday for zone 39. (See LAXNPWLOX).
Flash Flood Watch in effect through Tuesday morning for zones
39-52. (See LAXFFALOX).
High Surf Advisory in effect from 4 AM Tuesday to 2 PM PST
Wednesday for zones 39>41-87. (See LAXCFWLOX).
Wind Advisory in effect from midnight tonight to 3 PM PST
Tuesday for zones 40-41-44>46-88-547. (See LAXNPWLOX).
Flash Flood Watch in effect from 3 AM PST Tuesday through
Tuesday afternoon for zones 46-54-59. (See LAXFFALOX).
Winter Storm Warning in effect from 11 PM this evening to 8
PM PST Tuesday for zones 53-54. (See LAXWSWLOX).
Wind Advisory in effect until 4 AM PST Tuesday for zone 59. (See LAXNPWLOX).
High Wind Warning in effect from 4 AM to 1 PM PST Tuesday for
zone 59. (See LAXNPWLOX).
PZ...Gale Warning in effect until 3 AM PST Tuesday for zones
645-670. (See LAXMWWLOX).
Small Craft Advisory in effect until 7 PM PST this evening
for zones 650-676. (See LAXMWWLOX).
Gale Warning in effect until 9 PM PST Tuesday for zones
650-676. (See LAXMWWLOX).
Small Craft Advisory in effect until 1 AM PST Tuesday for
zone 655. (See LAXMWWLOX).
Gale Warning in effect from 1 AM to 9 PM PST Tuesday for zone
655. (See LAXMWWLOX).
Gale Warning in effect until 3 PM PST Tuesday for zone 673. (See LAXMWWLOX).
&&
.HAZARD POTENTIAL OUTLOOK (THU-MON).
No significant hazards expected.
&&
PUBLIC...Thompson
AVIATION...Phillips/Sweet
MARINE...Sweet/Phillips/Lund
SYNOPSIS...RAT
weather.gov/losangeles3 high wind, 2 winter storm. Local standard time, as filed.
Strong and gusty southerly winds impacted the interior valleys of San Luis Obispo county. Some peak wind gusts include: Cholame (gust 67 MPH), Falcon Road (gust 64 MPH), Navajo Flats (gust 64 MPH) and Highway 46 (gust 59 MPH).
Winter storm conditions impacted the mountains of Los Angeles county. Snowfall totals of 6 to 12 inches were reported above 7000 feet with 1 to 3 inches down to 5000 feet. Along with the snow, strong and gusty southerly winds developed with gusts in excess of 70 MPH. The strongest gusts were reported at Magic Mountain Truck Trail (gust 89 MPH) and Sierra Pelona (gust 82 MPH).
Winter storm conditions impacted the mountains of Ventura county. Snowfall totals of 6 to 12 inches were reported above 7000 feet with 1 to 3 inches down to 5000 feet. Along with the snow, strong and gusty southerly winds developed with gusts between 60 and 70 MPH reported.
Strong and gusty southerly winds impacted the mountains of San Luis Obispo county. Some peak wind gusts include: Frilis Camp (gust 64 MPH), Carrizo (gust 62 MPH) and Mount Lowe (gust 62 MPH).
Strong and gusty southwesterly winds impacted the Antelope Valley. Some peak wind gusts include: Juniper Mesa Road (gust 63 MPH), SCE-3480 (gust 61 MPH) and Llano (gust 59 MPH).
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: 994649, 994646, 994647, 994648, 994650.