A moderate Santa Ana wind occurred December 10, 2024. This mainly impacted the Inland Empire and the surrounding mountains passes and canyons.
Every event with a place to put it; 1 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 moderate Santa Ana wind occurred December 10, 2024. This mainly impacted the Inland Empire and the surrounding mountains passes and canyons.
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 10, 3:19 AM PST, 2 hours 41 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
319 AM PST Tue Dec 10 2024
.SYNOPSIS...
Moderate to locally strong Santa Ana winds for the mountains, Inland
Empire, inland Orange County, and San Diego valleys will peak in
strength this morning. Relative humidity values below 10 percent
combined with these strong winds will create critical fire weather
conditions today. Winds will diminish through Wednesday. A few
degrees of cooling is expected for Thursday and Friday. The marine
layer is expected to rebuild and deepen Thursday into Friday.
Slightly above average temperatures expected over the weekend
into early next week away from the coast, with marine layer low
clouds and fog near the coast each night and morning.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Gusty northeast to east winds were being observed in the mountains
and valleys at 3 AM. The strongest wind gust so far was recorded at
Sill Hill in San Diego County at 73 mph. Pleasants Peak (Santa
Ana mountains) is in second place with a gust of 67 mph recorded
and Banning (Riverside County) and Hauser Mountain (San Diego
County) are tied for third with both locations recording a gust of
66 mph. Winds are expected to peak in strength this morning.
Relative humidity values have already fallen to 5 to 15 percent
across the mountains and valleys. The strong winds and low
relative humidity, along with very dry vegetation due to our lack
of rain will create critical fire weather conditions today.
Winds are expected to weaken into Wednesday, but the very dry air
mass will remain. Cold, dry air being ushered into our area from the
Great Basin will have a big influence on temperatures, especially in
wind sheltered locations. This will be noticeable even today, with
highs for the mountains and deserts 7 to 15 degrees cooler than
yesterday. With the weaker offshore winds on Wednesday, highs in the
mountains and deserts will be a degree or two warmer, but still a
few degrees below average for this time of year. Overnight low
temperatures in wind sheltered locations will be significantly
cooler due to radiational cooling being maximized in the dry airmass
through Thursday morning.
A quick moving upper level low is expected to move into Northern
California Thursday. This will bring back onshore flow and marine
layer low clouds and fog. Latest local high resolution WRF shows
enough moisture returning to the coast by late Thursday night for
low clouds and fog to redevelop. Breezy southwest to west winds are
expected in the mountains, locally into the deserts Thursday night
into Friday. A few ensemble members from both the GEFS and ECMWF are
showing the potential for light precipitation for areas west of the
mountains Thursday night into early Friday. Current forecast keeps
precipitation chances less than 15 percent, but its possible the
increased onshore flow combined with a deepening marine layer could
squeeze some drizzle out of the rebuilding marine layer.
Mean ensemble solutions are showing a ridge of high pressure
building across the Southwest over the weekend and into early next
week. This should keep the area warm and dry with a shallow marine
layer. Current forecast follows the NBM with temperatures away from
the coast 5 to 10 degrees above average Saturday through Tuesday
December 17.
&&
.AVIATION...
101030Z....Clear skies will prevail today and tonight. Areas of
northeast to east winds will peak this morning, generally 25-45 kts,
strongest in south and west foothills and below canyons and passes
into adjacent valleys. Isolated VIS reductions in BLDU. Moderate to
strong up/downdrafts today over and in lee (southwest) of mountains
and foothills. Winds diminish this afternoon and evening, but local
gusts to 30 kts will continue into Wednesday morning.
&&
.MARINE...
Easterly winds with occasional gusts to around 20 knots will peak
this morning and decrease this afternoon. No hazardous marine
weather conditions are expected through Saturday.
&&
.FIRE WEATHER...
Strong winds, low humidity, and dry fuels will lead to critical fire
weather conditions for the valleys, inland Orange County, and
mountains today.
Gusty northeast to east winds are expected to peak in strength this
morning before diminishing into Wednesday. Strongest winds will
occur on mountain foothills, through passes, and into adjacent
inland valleys. Gusts 50 to 65 mph expected through favored passes
and on mountain foothills, isolated gusts to 70 mph are expected in
typically wind prone locations. Gusts of 35 to 55 mph are expected
in the Inland Empire below the Cajon and San Gorgonio Passes, inland
Orange County east of I-5, and in the San Diego County valleys.
Local gusts up to 60 mph are expected in the San Diego County
valleys with the strongest winds for areas east of El Cajon,
Poway, and Escondido.
Relative humidity values of 5 to 10 percent for inland areas and 15
to 20 percent at the coast today. Overnight humidity recovery will
be poor, only increasing to 15 to 30 percent tonight into Wednesday.
Wednesday will see lighter winds but humidity will still fall to 5
to 15 percent in the afternoon. Humidity is expected to recover into
Thursday with inland afternoon relative humidity values 15 to 30
percent. Further humidity recovery is expected into Friday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until 4 AM PST Wednesday for Orange County
Inland Areas-Riverside County Mountains-Including The San
Jacinto Ranger District Of The San Bernardino National
Forest-San Bernardino County Mountains-Including The
Mountain Top And Front Country Ranger Districts Of The San
Bernardino National Forest-San Bernardino and Riverside
County Valleys -The Inland Empire-San Diego County Inland
Valleys-San Diego County Mountains-Including The Palomar
And Descanso Ranger Districts of the Cleveland National
Forest-San Gorgonio Pass Near Banning-Santa Ana Mountains-
Including The Trabuco Ranger District of the Cleveland
National Forest.
PZ...None.
&&
PUBLIC/FIRE WEATHER...CO
AVIATION/MARINE...MMPreliminary Local Storm Report
National Weather Service San Diego CA
508 AM PST Tue Dec 10 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0450 AM Non-Tstm Wnd Dmg 1 E Alpine 32.83N 116.73W
12/10/2024 San Diego CA Dept of Highways
Overturned semi truck on I-8W on East
Willows Road near Alpine. Wind gusts at the
time of the incident (around 4:50 AM) were
47-52 mph.
&&
coPreliminary Local Storm Report
National Weather Service San Diego CA
515 AM PST Tue Dec 10 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0510 AM Non-Tstm Wnd Dmg 7 WSW Campo 32.60N 116.58W
12/10/2024 San Diego CA Dept of Highways
Tree down blocking both east and west bound
lanes of Sr 94 near Harris Ranch Rd (near
Tecate). Wind gusts in the area were gusting
between 55 and 59 mph.
&&
coThe national radar mosaic for the moment the first event began.
1 strong wind. Local standard time, as filed.
Traffic signal damaged on Limonite Ave and I-15 from Santa Ana winds.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2024Every state in 2024This day in weather historyWarnings in California, December 2024
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: 1228361.