Strong surface high pressure in the Great Basin generated another round of gusty Santa Ana winds across Southern California. Across the interior valleys of Ventura county, northeast wind gusts up to 85 MPH were reported.
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.
Strong surface high pressure in the Great Basin generated another round of gusty Santa Ana winds across Southern California. Across the interior valleys of Ventura county, northeast wind gusts up to 85 MPH 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 6, 4:36 PM PST, 3 hours 2 minutes earlier.
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
436 PM PST Wed Dec 6 2017
.SYNOPSIS...
Moderate to strong Santa Ana winds will likely continue to bring
very dry conditions with extreme fire danger through Friday for
much of Southwest California. The dry airmass will support another
round of frost and freeze conditions to wind sheltered locations.
The offshore flow and building ridge of high pressure over the
West Coast will support a daytime warming trend into this
weekend.
&&
.SHORT TERM...(TDY-SAT)
Offshore flow continues today but weaker gradients and upper
support than the last couple days. However, another inside slider
and cold pool of air is expected to drop into the Great Basin
tonight providing a reinforcing shot of offshore flow and upper
support. This will cause winds to strengthen tonight and Thursday
and lead to a similar windy period as we saw Monday into Tuesday
morning. All previously issued wind headlines look good.
Advisories for the LA/Ventura valleys will ramp up to warnings at
10pm tonight, warnings for the mountains as well as advisories
for the coast will continue as they are.
Temperatures warmed up several degrees today as the cold air from
the previous Great Basin trough exited and downslope flow from the
offshore gradients and subsidence from the ridge aloft really
cranked up the temperatures at lower elevations. As this next
trough arrives tonight and Thursday the source air will again cool
but strengthening offshore gradients and subsidence will offset at
least some of that cooling. So either similar or perhaps slightly
cooler temps Thu, with interior areas the most likely to cool off.
On Friday gradients relax by about 2 mb and upper support drops
off as well so the peak of this next event definitely appears to
be late Wednesday night through mid afternoon Thursday. It's
possible high wind warnings for some areas Friday may be heavy
handed but will re-evaluate that Thursday after the winds peak.
Offshore flow continues to weaken into Saturday but still likely
worthy of advisories at least for the valleys and mountains.
Temperatures expected to climb a degree or two as well.
.LONG TERM...(SUN-WED)
No rain. Not even close. A long wave ridge will remain in place
along the West Coast with just a couple weak upper lows floating
by at times. Models maintain weak offshore flow the whole period
along with very low humidities with just some sub-advisory level
northeast winds at times. Temperatures will remain well above
normal for coast/valleys and near to slightly above normal for
interior areas.
&&
.AVIATION...07/0020Z...
At 0015Z, there was a weak surface-based inversion at KLAX. The
top of the inversion was at 700 ft with a temperature of 19 deg C.
Generally hi confidence in the 00Z TAFs. Mostly VFR conditions
across the airfields during the next 24 hours, except MVFR vsbys
at times due to haze and smoke with nearby wildfires, especially
at KOXR, KSBA, KLAX, and KSMO. NE winds will be strengthening
once again tonight into Thursday, with strong uddfs and llws
becoming more common across airfields in Ventura and Los Angeles
counties.
KLAX...Hi confidence in the 00Z TAF with mostly VFR conditions
expected thru Thu afternoon. There is a 30 percent chance of MVFR
vsbys due to smoke at times from nearby wildfires. LLWS and
strong uddfs will become likely overnight into early Thursday
afternoon, as NE winds increase sharply just above ground level.
KBUR...Hi confidence in the 00Z TAF with VFR conditions generally
expected thru Thu afternoon. However, there is a 20 percent
chance for MVFR vsbys at times due to smoke from a nearby
wildfire. N to NE winds will strengthen overnight into Thursday
at KBUR with increasing probability of LLWS and strong uddfs.
&&
.MARINE...06/200 PM.
South of Point Conception, good confidence that SCA level wind
gusts will affect mostly areas From Pt. Mugu to Santa Monica
through late tonight, then increase with gale gusts late tonight
through Thursday. A SCA is in effect for PZZ655 for these Santa
Ana Winds. a Gale Warning has been issued for PZZ650 and PZZ655
late tonight thru Thu. Strongest winds will occur between Ventura
to Malibu, then across the San Pedro Channel to Avalon Harbor
early Thursday morning through the afternoon.
Northeast winds gusting to between 25 and 30 knots late tonight
and Thursday will likely affect the San Pedro Channel out to
Catalina Island with short-period hazardous seas of 3 to 6 feet.
The wind driven seas will cause boating hazards for east-facing
harbors and inlets, such as Avalon Harbor and other offshore
islands. Expect more widespread rough seas across the inner waters
Thursday.
The outer waters of PZZ676 is expected to have SCA gusts later
this evening thru Thu, and an SCA has been issued for this area as
well.
N. of Point Conception...Not expecting SCA winds through Friday.
&&
.FIRE WEATHER...06/130 PM.
The Red Flag Warning for Los Angeles and Ventura Counties has been
extended through Saturday 8 PM. A Red Flag Warning has been issued
for the Santa Barbara County Mountains for 6 PM tonight through 9
AM Friday.
An extended moderate to strong Santa Ana wind event
will continue over much of Los Angeles and Ventura Counties through
at least Saturday. The winds are expected to strengthen again
tonight through Thursday with 18 to 24 hours of strong winds gusting
to 50 to 80 mph. This is a significant period. The winds will then
gradually weaken Friday through Sunday. Meanwhile, minimum
humidities of 5 to 10 percent will be common through at least early
next week, with widespread very poor overnight recoveries staying
under 30 percent. As a result, critical Red Flag conditions will
persist over most of Los Angeles and Ventura through Saturday, and
possibly through Sunday in some or all of those locations. All other
areas will remain in elevated fire weather conditions with locally
breezy offshore flow and prolonged dry conditions. The Santa Barbara
and possibly the San Luis Obispo Mountains and foothills will
approach critical conditions tonight through early Friday as easterly
winds strengthen.
There is a chance that offshore flow and near-critical conditions
will continue through the middle of next week. No rain possibilities
over the next 10 days.
If fire ignition occurs, very rapid spread and extreme fire
behavior is likely. Everyone needs to exercise extreme caution
when handling any potential fire ignition sources...such as
campfires, cigarettes, welding and brush clearing equipment.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Frost Advisory in effect from 1 AM to 9 AM PST Thursday for
zones 34>36. (See LAXNPWLOX).
Wind Advisory in effect until 4 PM PST Friday for zones
40-41. (See LAXNPWLOX).
Wind Advisory in effect until 10 PM PST this evening for
zones 44-45-88-547. (See LAXNPWLOX).
High Wind Warning in effect from 10 PM this evening to 4 PM
PST Friday for zones 44-45-88-547. (See LAXNPWLOX).
High Wind Warning in effect until 4 PM PST Friday for zones
46-53-54. (See LAXNPWLOX).
Red Flag Warning in effect until 8 PM PST Saturday for zones
240-241-244>246-253-254-288-547-548. (See LAXRFWLOX).
Red Flag Warning in effect until 9 AM PST Friday for zone
252. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect from 9 PM this evening to 3 AM
PST Thursday for zone 650. (See LAXMWWLOX).
Gale Warning in effect from 3 AM to 6 PM PST Thursday for
zones 650-655. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PST Thursday for
zone 655. (See LAXMWWLOX).
Small Craft Advisory in effect from 9 PM this evening to 6 PM
PST Thursday for zone 676. (See LAXMWWLOX).
&&
.HAZARD POTENTIAL OUTLOOK...(SAT-WED)
Advisory level Santa Ana winds expected Saturday, especially in
the mountains and valleys along with very low humidities.
Extremely critical fire weather conditions will continue through
at least Saturday and possibly into early next week.
&&
PUBLIC...MW
AVIATION...Gomberg
MARINE...Sirard
FIRE...Kittell
SYNOPSIS...Sweet
weather.gov/losangelesPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OXNARD CA
700 PM PST WED DEC 06 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0656 PM NON-TSTM WND GST 5 WSW WESTLAKE VILLAGE 34.11N 118.90W
12/06/2017 M61 MPH VENTURA CA MESONET
BONEY MOUNTAIN COMMUNITY WEATHER OBSERVER PROGRAM
OBSERVING STATION.
&&
SMITHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OXNARD CA
702 PM PST WED DEC 06 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0701 PM NON-TSTM WND GST 8 NNE MOUNT WILSON 34.33N 118.03W
12/06/2017 E62 MPH LOS ANGELES CA MESONET
RAWS STATION
&&
SMITHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OXNARD CA
707 PM PST WED DEC 06 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0701 PM NON-TSTM WND GST 4 NNE SAN FERNANDO 34.35N 118.42W
12/06/2017 E60 MPH LOS ANGELES CA MESONET
RAWS STATION CAMP 9.
&&
SMITH1 high wind. Local standard time, as filed.
Strong northeast winds were reported across the interior valleys of Ventura county. The RAWS sensor at Boney Mountain reported northeast wind gusts between 73 and 85 MPH. A sensor at Decker Canyon reported wind gusts up to 73 MPH.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, December 2017
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: 729834.