A cold Winter storm impacted the mountains of Central and Southern California. Snowfall totals, ranging from 2 to 8 inches, and wind gusts up to 65 MPH created winter storm conditions across the mountains of San Luis Obispo, Santa Barbara, Ventura and Los Angeles counties.
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.
A cold Winter storm impacted the mountains of Central and Southern California. Snowfall totals, ranging from 2 to 8 inches, and wind gusts up to 65 MPH created winter storm conditions across the mountains of San Luis Obispo, Santa Barbara, Ventura and Los Angeles counties.
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 Jan 24, 10:14 PM PST, 3 hours 46 minutes earlier.
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1014 PM PST Sun Jan 24 2021
.SYNOPSIS...24/934 PM.
Another cold storm system with low snow levels will move over
the region through Monday. A cool, showery, and unsettled weather
pattern will be prevalent on Monday with gusty winds, potentially
damaging across the interior portions. Drier conditions are
forecast for Tuesday, then a wetter storm system will slowly move
over the region between Tuesday night through Thursday.
&&
.SHORT TERM (SUN-WED)...24/1013 PM.
The latest infrared imagery shows a cold upper-level trough
digging and elongated along the West Coast this evening. This
trough will dig into the area on Monday, bottoming out in the
Mojave Desert on Monday afternoon. The latest radar imagery shows
showers spreading south into Central Coast this evening with
vorticity maximum, and showers developing in a diffluent area on
the leading edge of the trough. A few lightning strikes occurred
in the San Gabriel Valley earlier this evening and showers
intensified briefly. An showery weather pattern will develop
through tonight and Monday as a cold air mass aloft spreads into
the area. PoPs and precipitation amounts look reasonable and no
update are planned at this time. Steepening lapse rates will
likely destabilize the air mass and bring another threat of
thunderstorms (a slight chance) to the area on Monday. 700 mb
temperatures dropping to between -11 degrees Celsius and -15
degrees Celsius will drop snow levels to between 1500 and 2000
feet. Snow levels this low could possibly bring a mix of rain and
snow for the foothill areas of southern California and the
potential for small hail or graupel to develop across the coastal
and valley areas.
A windy and cold pattern will spread into the region on Monday.
Gusty winds will mix with a cold air mass to make it feel colder
on Monday. The latest model solutions show strong wind support
moving aloft. 950 and 850 mb winds increase to near 45 and 50
knots. Gusty and potentially damaging winds will develop across
the interior portions of the area and the mountain areas. Wind
Advisories were added for the coastal areas and for coastal and
valley areas north of Point Conception. A Wind Advisory for the
Antelope Valley was replaced with a High Wind Warning. In the
mountains and the Cuyama Valley, gusty and potentially damaging
wind will mix with snow. A Winter Weather Advisory was added for
the Cuyama Valley and a Winter Storm Warning replaces a High Wind
Warning as snow and winds could mix at times to create treacherous
travel conditions.
***From Previous Discussion***
Overall, 12Z models in good synoptic agreement through the short
term period. At upper levels, a disturbance will move south into
the area tonight, forming an low on Monday/Monday night. On
Tuesday, a weak ridge will develop, but another much more potent
system will approach the area on Tuesday night and Wednesday.
Near the surface, gusty northwesterly flow through Monday with
flow turning southeasterly by Wednesday.
Overall, no major changes to anticipated active weather pattern
for the area through the week. The system moving through the area
tonight and Monday still looks on track with previous thinking. A
weakening frontal system will bring rain to the Central Coast this
evening with a shower threat developing all areas late tonight
through Monday night. Rainfall totals still do not look too overly
impressive. Through Monday night, the Central Coast as well as LA
county will receive 0.25-0.75 inches with the highest totals in
the foothills. For Ventura county, rainfall total will generally
range between 0.05-0.15 inches due to shadowing effect of
northwesterly winds. Also, interior sections of SLO/SBA counties
as well as the Antelope Valleys can expect around 0.10 inches or
less. One change with the forecast was to add the slight chance of
thunderstorms to all areas on Monday as plenty of cold and
unstable air filters into the area. Any thunderstorms that develop
could produce brief heavy showers, small hail and gusty winds. As
for snow levels, expect snow levels to drop around 2000 to 2500
feet tonight and Monday. In the SBA/Ventura/LA mountains, snow
accumulation between 2 and 8 inches is expected along with
northwest winds gusting around 60 MPH. So, will upgrade to a
WINTER STORM WARNING for these areas from 10 PM tonight through
10 PM Monday evening. Could be some very light snow accumulations
in the local foothills, so will need to watch those areas closely
overnight.
After a brief respite through Tuesday afternoon, next more potent
system will approach the area Tuesday night and Wednesday. 12Z
models continue to hang up this system across the Central Coast
Tuesday night and Wednesday. So, rain will overspread SLO and SBA
counties Tuesday night and Wednesday with the potential for heavy
rainfall Wednesday and Wednesday evening. For Ventura and LA
counties, there will be a chance of rain on Wednesday, but heavier
precipitation will hold off until Thursday or Thursday night.
Through Wednesday evening, SLO and SBA counties are expected to
receive between 2 and 4 inches of rainfall with amounts dropping
down to 0.10-0.25 inches across LA county. Strong southerly flow
ahead of the system will allow for snow levels to increase to
around 5000 feet on Wednesday. Additionally, these southerly winds
could exceed 60 MPH in some areas across SLO and SBA counties and
will need to be watched closely.
.LONG TERM (THU-SUN)...24/152 PM.
For the extended period, focus continues to remain on very potent
storm system Thursday and Friday. As mentioned in the short term
discussion, the front hangs up over the Central Coast on Wednesday
and remains hung up over the Central Coast through Thursday
morning. So, moderate to heavy rainfall will continue across SLO
and SBA counties with lesser rainfall across Ventura and LA
counties. By Thursday afternoon (ECMWF) or Thursday evening (GFS),
the front will begin to move southward with heavier precipitation
developing over Ventura and LA counties Thursday night/Friday
morning with the rain tapering off by Friday evening. Despite the
timing differences, either solution will result in a very
significant precipitation event. Overall, rainfall totals from
Tuesday night through Friday evening are expected to range from
4-8 inches across SLO/SBA counties to 1.50-4 inches across Ventura
and LA counties. Southerly flow ahead of the system will keep snow
levels around 5000-5500 feet on Thursday and Friday. So, higher
mountain elevations can expect some significant snowfall
accumulations (1-2 feet potentially) if not a little more at the
highest elevations. Additionally, the southerly winds associated
with this system look to be pretty strong. So, widespread advisory
level winds are likely in many areas with the potential for
warning level winds.
There will be a myriad of hazards across the area Tuesday night
through Friday. Rainfall amounts and intensities could produce
debris flow problems in and around recent burn area. Dangerous
winter weather conditions are likely in the mountains. The
combination of gusty southerly winds and a rain-soaked ground
could result in some down limbs or trees. Overall, this is a very
significant weather event on tap for our area.
On Saturday and Sunday, there is the potential for a weak storm
to impact the area. At this time, rainfall amounts look to be very
sparse. However, enough of a precipitation threat to warrant
chance or slight chance POPs for the area.
&&
.AVIATION...25/0040Z.
At 2330z at KLAX... There was no marine inversion.
Overall... Moderate to high confidence in the current TAFs. MVFR/low
VFR CIGs will develop in most areas this evening and continue
overnight as showers move through the region. Strong and gusty
west to northwest winds will also develop across the region
tonight and overnight and will be particularly strong in the
Antelope Valley. Otherwise and elsewhere, VFR conditions will
prevail.
KLAX...Moderate to high confidence in the current TAF. MVFR/low
VFR CIGs will develop this evening and continue overnight as
showers move through the region. Gusty west to northwest winds
will also develop tonight and continue overnight. The winds could
gust over 35 knots after 12z. Otherwise, VFR conditions will
prevail. There will not be any east winds greater than 8 kts
during the forecast period.
KBUR...Moderate to high confidence in the current TAF. MVFR/low
VFR CIGs will develop this evening and continue overnight as
showers move through the region. Strong and gusty winds will also
develop overnight. Otherwise, VFR conditions will prevail.
&&
.MARINE...24/850 PM.
***There will be very dangerous wind and sea conditions across
the entire coastal waters tonight through early Tuesday***
West to NW winds and seas will increase significantly and quickly
tonight, with widespread Gale force winds developing in most
areas by late evening. Gale force W to NW winds will continue
through Tuesday morning then diminish somewhat before increasing
again on Wednesday.
There is a thirty percent chance that wind gusts could reach
STORM WARNING levels of 50 knots in some areas Monday and early
Monday night anywhere in the coastal waters, even near the coast.
Seas will build rapidly tonight and become extremely dangerous
due to the size and steepness. Seas will peak at 15 to 20 feet
across the outer waters and the inner waters along the Central
Coast Monday and Monday night and at 10 to 14 feet across the
inner waters south of Point Conception, including the Santa
Barbara Channel. This will be a particularly dangerous episode of
winds and seas across the coastal waters.
Winds will diminish midday Tuesday and may even drop below SCA
levels for a while. However, winds will shift to the south and
increase again Tuesday night, reaching SCA levels in most areas
late Tuesday night through Thursday, with Gale force winds
possible in the outer waters and the inner waters along the
Central Coast on Wednesday.
&&
.BEACHES...24/851 PM.
Surf will build to 8 to 12 feet on the Central Coast overnight and
peak at 14 to 18 feet with local sets to 20 feet Monday into
Monday night. On west facing beaches south of Point Conception,
surf will build to 8 to 12 feet with local sets to 14 feet on
Monday and Monday night. Surf will slowly subside on Tuesday
before increasing again on Wednesday.
There will be minor coastal flooding Monday through Tuesday
morning, especially near high tide. There will be strong and
dangerous rip currents on all area beaches through Tuesday.
&&
.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 10 PM PST Monday for zones
34>36-39-59. (See LAXNPWLOX).
Wind Advisory in effect from 4 AM to 10 PM PST Monday for
zone 37. (See LAXNPWLOX).
Winter Weather Advisory in effect until 10 PM PST Monday for
zone 38. (See LAXWSWLOX).
High Surf Advisory in effect from 6 AM Monday to 6 PM PST
Tuesday for zones 39>41-87. (See LAXCFWLOX).
Wind Advisory in effect from 8 AM to 10 PM PST Monday for
zones 40-41. (See LAXNPWLOX).
Freeze Watch in effect from late Monday night through Tuesday
morning for zones 44-45-88. (See LAXNPWLOX).
Winter Storm Warning in effect until 10 PM PST Monday for
zones 51>54. (See LAXWSWLOX).
High Wind Warning in effect until 10 PM PST Monday for zones
59-549-550. (See LAXNPWLOX).
Wind Advisory in effect until 3 AM PST Tuesday for zone 87. (See LAXNPWLOX).
PZ...Gale Warning in effect until 3 PM PST Tuesday for zones
645-650-655-670-673-676. (See LAXMWWLOX).
&&
.HAZARD POTENTIAL OUTLOOK (WED-SUN).
Moderate to heavy rainfall and mountain snow is likely Wednesday
through Friday. Rainfall intensities could result in debris flow
issues for the recent burn areas. Gusty southerly winds could
result in downed limbs, trees and power lines.
&&
PUBLIC...Hall/Thompson
AVIATION...Kj
MARINE...Kj
BEACHES...Kj
SYNOPSIS...Hall
weather.gov/losangeles4 winter storm. Local standard time, as filed.
Winter storm conditions impacted the mountains of San Luis Obispo county. Although snowfall totals were light (between 1 and 2 inches), southerly wind gusts up to 65 MPH created hazardous winter storm conditions.
Winter storm conditions impacted the mountains of Santa Barbara county. Snowfall totals of 1 to 3 inches combined with southerly winds, gusting up to 67 MPH, to produce hazardous winter weather conditions.
Winter storm conditions impacted the mountains of Ventura county. Snowfall totals between 3 and 6 inches and southerly wind, gusting up to 65 MPH, combined to produce hazardous winter weather conditions.
Winter storm conditions impacted the mountains of Los Angeles county. Snowfall totals between 3 and 8 inches combined with southerly winds, gusting up to 65 MPH, to produce hazardous winter weather conditions.
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, January 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: 942736, 942737, 942738, 942739.