A low pressure system from the north moved into Southern California, bringing rain, mountain snow and gusty winds. The San Bernardino Mountains received a few inches of snow, heaviest overnight on the 30th.
Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
A low pressure system from the north moved into Southern California, bringing rain, mountain snow and gusty winds. The San Bernardino Mountains received a few inches of snow, heaviest overnight on the 30th. Snow Summit received 4-6 inches, Big Bear City received 4 inches, and Big Bear Lake received 2-3 inches. Winds were a big impact with this storm, especially in the mountains and passes. The Cajon Pass (I-15) had numerous big rigs overturned due to strong winds. A fatality occurred on highway 79, where the driver drove the car into a downed tree over the highway.
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 29, 9:16 PM PST, 2 hours 44 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
916 PM PST Sun Dec 29 2019
.SYNOPSIS...
A cold storm will drop south along the California Coast tonight
through Monday night. The bulk of the rain with this system now
looks like it will remain offshore. However, wrap around moisture
associated with the storm may result in snow across the mountains
of San Bernardino and Riverside Counties. In the wake of this
system, high pressure will build across southern California,
resulting in dry weather and a warming trend for the middle to
latter part of the week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE...
The center of an upper level low is currently about 200 miles west
of Monterey with a band of mostly light rain moving inland across
the Central CA coast. Latest guidance still suggests the low and
most precipitation associated with it will remain off the coast as
it digs south and slightly further east. Best chances of rain will
be along the coast, though not much is expected in terms of
accumulations. Moisture along the eastern edge of this system will
drop through interior portions of CA, and developing northeast
flow with this moisture may provide for some orographic
precipitation along the northern slopes of the San Bernardino
Mountains and desert foothills. Elsewhere will likely only see a
couple hundredths of an inch at best. Only changes to the forecast
this evening were to continue the downward trend in PoPs and QPF,
with the largest changes in the valleys and low desert.
PREVIOUS DISCUSSION...
An upper low now off the northern California coast will continue
to move southward remaining offshore before reaching the central
Baja peninsula on Tuesday. In the last couple of runs, the models
have finally come into good agreement on this system. The bulk of
the precipitation associated with it is expected to remain
offshore. Only light rain is expected across the coast, valleys,
and desert areas with accumulations expected to range from a trace
to around a tenth of an inch. Best chance of accumulating rainfall
will be near the immediate coast.
Over the mountains of San Bernardino and Riverside Counties,
models are in good agreement on a zone of wrap-around moisture
persisting for about a 24 hour period resulting in periods of
light snow from tonight through Monday night. Total snow
accumulations are expected to average 1 to 4 inches, with isolated
totals of 4 to 8 inches. The highest accumulations will be over
the San Bernardino County mountains, with lesser amounts in the
mountains near Idyllwild. Snow accumulations will likely impact
the Cajon Pass area (I-15) along with the mountain portions of state
highways 18, 38, 138, 74, and 243. Will see wind gusts of 35 to 50
mph over portions of the mountains Monday night which will add to
the hazardous travel conditions.
Given the low snow levels and that this is a holiday travel
period, issued a Winter Weather Advisory for the San Bernardino
and Riverside County mountains. Further south over the San Diego
County Mountains, there is a chance for light snow to occur but
confidence is far too low on any accumulations to warrant any
headlines. For the high desert, light snow is also possible but
again not high enough confidence on accumulation potential to
warrant an advisory. Will need to watch this area closely on
Monday.
Used a blend of NBM and WPC guidance for the QPF forecast, and
coordinated the forecast closely with WFOs Oxnard and Hanford.
The storm system will exit the area Tuesday, with dry weather
expected the remainder of the week in its wake. Another upper
trough will pass well east of the area Thursday over Nevada and
the Four Corners region. In the wake of this second trough, upper
ridging will build directly over southern California by Friday
and Saturday. Expect a warming trend by late week. Looking out in
the long range, the next potential for precipitation looks to be
no earlier than mid next week, well beyond the forecast period.
&&
.AVIATION...
230500Z...Mostly BKN-OVC clouds will prevail through Mon evening
with cloud bases mainly 8000-12000 ft MSL but with areas of bases
2500-5000 ft MSL mainly 08Z-18Z Mon. Scattered -SHRA are possible
09Z-20Z Mon with -SHSN possible in the San Bernardino County
Mountains. Mountain terrain will be locally obscured by clouds 09Z-
20Z Mon, but most vis will remain unrestricted below the clouds.
Areas of northeast surface winds 15-25 knots with gusts to 35 knots
will develop after 14Z Mon from the mountain crests south and west
through the foothills with LLWS and moderate up/downdrafts. LLWS
could affect KONT or KSNA by late Mon.
&&
.MARINE...
No hazardous marine conditions are expected through Wed. SE to
E winds could have gusts to near 20 knots Mon, but winds will likely
remain below small craft advisory criteria. A large west swell
Thu/Fri will likely bring seas of 8-10 feet.
&&
.BEACHES...
Locally elevated surf is likely at San Diego County beaches
Tuesday as a medium-period WNW swell arrives. Confidence
is high for widespread high surf conditions starting early Thursday,
with highest surf in San Diego County. A 19-second swell from the
WNW will likely bring surf of 8-10 feet in parts of San Diego
County beaches, locally higher, and 6-9 feet along the Orange County
beaches.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory from 2 AM Monday to 4 AM PST Tuesday for
Riverside County Mountains-San Bernardino County Mountains.
PZ...NONE.
&&
PUBLIC...SS
AVIATION/MARINE/BEACHES...MaxwellThe national radar mosaic for the moment the first event began.
3 strong wind, 3 high wind, 1 winter weather. Local standard time, as filed.
A few inches of snow fell in the San Bernardino County mountains December 30-31st. Total snow accumulations: Snow Summit 4-6 inches, Big Bear City 4 inches, Big Bear Lake 2-3 inches.
Numerous tractor trailers were blown over on I-15 through the Cajon Pass on December 30th and 31st.
Devil Canyon reported a peak wind gust of 50 knots around 940 PST on December 30th.
Highland Springs meson reported a peak wind gust of 50 knots around 1200 PST on December 30th.
Sill Hill reported a peak wind gust of 56 knots around 1700 PST on December 30th.
CalTrans reported a fatality on Highway 79 near Aguanga around 0545 AM PST on December 31st. The individual drove into a downed tree across the highway. Winds are estimated to be around 40 mph at the time of the accident.
KTLA reported a tree down on a truck in Santa Ana due to strong winds. Winds are estimated to be around 30-40 mph.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Strong Wind, San Diego County Mountains | 2019-12-31 | Vehicle/Towed Trailer | Indirect |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2019Every state in 2019This day in weather historyWarnings in California, December 2019
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: 870487, 870489, 870498, 870497, 870495, 870491, 870493.