An upper level trough and the tail end of a Pacific cold front traversed the region on the 15th and 16th of December. Though showers were reported across the region, the main impact was wind, with gusts exceeding 70 mph along the desert slopes.
Every event with a place to put it; 6 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.
An upper level trough and the tail end of a Pacific cold front traversed the region on the 15th and 16th of December. Though showers were reported across the region, the main impact was wind, with gusts exceeding 70 mph along the desert slopes. Winds associated with a mountain wave also briefly surface in the Coachella Valley, producing minor damage in southern La Quinta. Rain and patchy dense fog along the coastal slopes impacted driving conditions. San Diego County reported 546 traffic accidents (390% of normal), one traffic accident resulted in a fatality along Interstate 8.
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 15, 4:00 PM PST, 4 hours 50 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
400 PM PST Thu Dec 15 2016
...HIGH WIND WARNING FOR THE MOUNTAIN RIDGE TOPS AND DESERTS...
...FLASH FLOOD WATCH FOR THE SAN BERNARDINO COUNTY MOUNTAINS...
.QUICK UPDATE...
Just sent an update to add blowing dust & sand to the lower deserts
for Friday afternoon when the greatest potential for high winds will
be and the pops low. No other changes to the forecast for now.
&&
.SYNOPSIS...
A Pacific storm will move across Southern California overnight
and Friday, bringing widespread rain along with strong winds in
the mountains and deserts. Cool and dry weather will arrive behind
the storm this weekend with brisk offshore winds. Fair and only
slightly warmer next week with offshore flow.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
The Pacific storm is nicely seen on water vapor imagery off the
California coast centered at about 31N 129W. A plume of moisture,
an atmospheric river, lies ahead of the storm and will move across
Southern California overnight through Friday morning before
shifting to Southeast of the area late in the day Friday.
Strengthening West-Southwest wind fields, along with the
increasing moisture to some 200-350% of average, will lead to an
efficient upslope precip event.
Rain will increase this evening. Seeing some radar returns, mostly
mid level moisture increasing. Expecting showers to arrive in the
OC in the next couple of hours, spreading/developing east and
south through the evening. Intensity will pick up overnight,
especially in the upslope-favored locales with 1"+/hr rates
possible. The Friday morning commute looks to be extra slow with
rain-slicked roads expected along with reduced visibility due to
the rain and spray from traffic.
Hi-res models continue bullish on precip amounts, so have trended
amounts up for the coastal mountain slopes with amounts now over
4" forecast for the San Bernardino County mountains as well as the
San Jacintos of Riverside. Even the Santa Anas and northern San
Diego County mountains look to receive 2.5-3.5". Metropolitan
locales continue to look much less...with rain amounts of
0.50-1.00" forecast...similar to the previous forecasts. The
deserts look to average less than a quarter of an inch. Should
note that the hi-res NAM-based WRF shows maxima of 6-7" in the San
Bernardinos while the GFS-based WRF shows maxima there of just
over 5", so if those models verify, then max amounts could be
higher than currently forecast. However, sometimes WRF has a high
bias, so believe we have a solid QPF forecast.
This will be a relatively warm storm with high snow levels, so
resort locales are forecast to receive an inch or less. However,
just the highest peaks of San Gorgonio and San Jacinto could see
significant snowfall.
Winds are strengthening and we are still looking at strong winds
for the mountain ridge tops to parts of the deserts. A High Wind
Warning is in effect for these locales through Friday evening. WRF
continues to show a mountain wave surfacing and impacting portions
of the Coachella Valley, especially from Palm Springs to Palm
Desert after sunrise through noon on Friday. These can be
difficult to forecast, but it has been consistent so gusts to 60
mph are possible there with the most likely time after sunrise
through noon on Friday. For the metropolitan areas...gusts look
to average 20-30 mph.
From previous forecast...
Wind flow turns offshore early Saturday for a rapid clear out.
Mostly clear skies and a cold interior air mass will descend upon
Southern California Saturday. Temperatures will struggle to reach
60 at lower elevations. Locally gusty offshore winds are expected
below Cajon Pass into the northern Inland Empire on Saturday. The
offshore flow will strengthen Sunday and Monday when northeast
winds will peak. Next week will be fair, dry, and cool, but with a
modest warming trend.
&&
.AVIATION...
1521100Z...Coast/Valleys...Increasing clouds with multiple layers
developing between 8000-20000 ft MSL, lowering to 5000 ft MSL by
this afternoon. -SHRA will move into Orange County and NW Portions
of the Inland Empire by 00z, spreading SE and becoming heavier and
more widespread overnight with CIGS lowering to around 1500 ft MSL.
Occasional CIGS as low as 500 ft MSL with vis 3SM or less in heavier
showers late this evening into Friday morning. Vis improving Friday
afternoon as rain tapers off.
Mountains/Deserts...Increasing mid and high clouds through the day.
Showers possible beginning late this afternoon over San Bernardino
County, becoming heavier and spreading into Riverside and San Diego
Counties late this evening. Coastal mountain slopes becoming
obscured in clouds/fog tonight. In addition, gusty SW to W winds
developing along the ridges, desert slopes, and locally onto the
desert floor this afternoon, strengthening overnight. Sfc gusts 45-
60 kt likely overnight, along with SVR UDDFS, LLWS, and rotors over
and NE/E of the mtns, including near KPSP, KVCV, and KTRM.
&&
.MARINE...
A storm will bring strong winds and rough seas to the coastal waters
late tonight through early Saturday, resulting in hazardous boating
conditions. Strongest winds and highest seas will occur Friday
afternoon through Friday night. Conditions will improve during the
day Saturday. A Small Craft Advisory is in effect from midnight
tonight through 8 AM Saturday.
&&
.SKYWARN...
Skywarn activation is requested tonight through about midday
Friday. Spotters are encouraged to report significant weather
conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Warning until 8 PM PST Friday for Apple and Lucerne
Valleys-Coachella Valley-Riverside County Mountains-San
Bernardino County Mountains-San Diego County Deserts-San
Diego County Mountains-San Gorgonio Pass Near Banning.
Flash Flood Watch from 5 PM PST this afternoon through Friday
morning for San Bernardino County Mountains.
PZ...Small Craft Advisory from midnight tonight to 8 AM PST Saturday
for Coastal Waters from San Mateo Point to the Mexican
Border and out to 30 nm-Waters from San Mateo point to the
Mexican Border Extending 30 to 60 nm out including San
Clemente Island.
&&
PUBLIC...Gregoria
AVIATION/MARINE...TS
UPDATE...JMBThe national radar mosaic for the moment the first event began.
5 high wind, 1 dense fog. Local standard time, as filed.
A 71 mph westerly wind gust was reported by the Whitewater mesonet station. Strong wind gusts to 55 mph buffeted other eastern portions of the San Gorgonio Pass.
Strong winds over the San Bernardino County Mountains gusted in the 40-60 mph range, causing minor power line and tree damage in Big Bear City. East of Big Bear City, the mesonet station in Burns Canyon reported wind gusts in excess of 70 mph between 1351 and 1851PST, with a peak gust of 85 mph.
The Volcan Mountain mesonet station reported a 70 mph wind gust between 0500 and 0510PST. Other stations reported westerly wind gusts in the 40-55 mph range along the desert slopes in San Diego County.
Dense fog and rain limited visibility along Interstate 8 through the San Diego County Mountains. One person was killed when her vehicle drove off a cliff. Weather was confirmed as in influencing factor.
A surfacing mountain wave produced a strong wind gust that lifted part of a roof from a home in southwestern Lucerne Valley.
A mountain wave surfaced, downing large tree limbs in southern La Quinta. Several miles east the wave produced a gust of 56 mph at Jacqueline Cochran Regional Airport in Thermal.
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 |
|---|---|---|---|---|---|
| Dense Fog, San Diego County Mountains | 2016-12-16 | Female | Unknown | Indirect |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2016Every state in 2016This day in weather historyWarnings in California, December 2016
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: 669361, 669363, 669353, 670387, 669356, 669354.