A powerful winter storm moved across Southwestern California, bringing heavy rain and snow, strong winds and flash flooding to the area. Rainfall amounts ranged from 2 to 6 inches across coastal areas with up to around 10 inches in the local mountains.
Every event with a place to put it; 4 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 LOX wrote it up.
A powerful winter storm moved across Southwestern California, bringing heavy rain and snow, strong winds and flash flooding to the area. Rainfall amounts ranged from 2 to 6 inches across coastal areas with up to around 10 inches in the local mountains. This heavy rain produced numerous reports of flash flooding as well as mud and debris flows. In the local mountains, snowfall totals between 1 and 2 feet were reported at the resort level. Strong southerly winds accompanied the storm with wind gusts up to around 70 MPH reported in some areas.
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 Feb 17, 4:41 AM PST, 1 hour 34 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
441 AM PST Fri Feb 17 2017
New Aviation and Marine Discussions
.SYNOPSIS...
A strong trough of low pressure off the Central California Coast
will move over the region through Saturday bringing gusty winds
and rain and mountain snow. Rain, heavy at times will move over
the area today as the storm system's cold front move over the
region. Weak ridging aloft will establish on Sunday, then a series
of trough of low pressures will move ashore through midweek next
week.
&&
.SHORT TERM...(TDY-SUN)
The latest infrared imagery shows a strong upper-level trough of
low pressure currently centered near 38N and 133W, or about 880
miles west-northwest of Los Angeles. A diffluent flow pattern is
seen easily developing off the California Coast early this morning
as the storm is starting to intensify. The surface low
circulation sits just ahead of the upper-level trough center. With
diffluent flow aloft and the strong lifting taking place, the
surface low will deepen and intensify as it moves towards the San
Francisco Bay through this evening.
Isolated thunderstorms remain a threat areawide as deep lift
through the atmosphere should steepen lapse rates. Rainfall rates
are starting to approach a quarter-inch per hour this morning as
the diffluent area approaches Point Conception. Rainfall rates
should pickup through this morning as the instability and deep
lift punches in. Satellite passes offshore indicate 0.50 inch per
hour rainfall rates occurring offshore and these rates should
intensify by at least a factor of two as orographic lift comes
into play and the storm system interacts with the terrain.
A flash flood watch remains in effect from 7 am pst this morning
through Saturday morning for Santa Barbara, Ventura and Los
Angeles Counties. A tightening surface gradient will develop
through sunrise as the surface low center nudges closer to the
area. Strong southerly flow will bring gusty and potentially
damaging winds to all areas of Southwest California. Wind
headlines remain mostly intact, except a few tweaks were made to
start times. Southerly winds will interact with the topography to
enhance lift through today as the flow upslopes into the
Transverse Mountains. QPF values remain between two and six
inches for coastal and valley areas with up to five to ten inches
across the foothills and mountains. South-facing slopes will see
the highest precipitation totals across the area.
Snow levels between 7500 to 8000 feet this morning will gradually
fall through Saturday morning to between 5000 and 5500 feet. A
winter storm warning remains in effect from 7 am pst this morning
through Saturday morning. Snow amounts will really start to add up
after this afternoon as colder air aloft punches in. One foot to
two feet of snow is possible above 8000 feet with this storm
system. Local amounts up to three feet cannot be ruled out on
favored high mountain peaks. Snow amounts between 6000 and 7500
feet will likely range to between six and twelve inches.
The cold front with the system will move west to east over the
region between late this morning through this evening. The front
will exit Los Angeles County just after sunset. A showery weather
pattern will linger into Saturday night and the potential for
isolated will linger as the 500 mb cold pocket moves over the
area. Showers with isolated thunderstorms remain in the forecast
for some areas into Saturday evening.
Weak ridging should build in for Sunday and the area should dry
out.
.LONG TERM...(MON-THU)
Another system will approach the Central Coast between Sunday
night and Monday, then drift southward into Tuesday while losing
its punch. The best chance of rainfall looks to be for the Central
Coast where the best mositure is.
Models are still waffling for the pattern for mid-to-late week
next week, but model trends suggest troughing along the Central
California Coast between Tuesday night and Wednesday. With most
time and effort paid to the short-term, forecast remains
consistent for now.
&&
.AVIATION...17/1220Z
At 0900Z, there was a weak inversion at KLAX at 2000 ft. The top
of the inversion was 3600 ft with a temperature of 12 deg c.
Very low confidence in the 12Z TAFs due variable low cigs/vsbys
assoc with moderate to heavy rain. Flight category may be off by
1 or more with timing of category change off by up to 3 hours,
locally more. There is a 20 percent chance of a thunderstorm at
any TAF site through the TAF period. Timing of wind shifts may be
off by up to 3 hours with wind speed off by up to 5 kts.
KLAX...Very low confidence in the 12Z TAF due variable low
cigs/vsbys assoc with moderate to heavy rain. East winds likely
above 10 kts 14Z to 20z. There is a 50 percent chance that
southerly cross winds with exceed 25 kts between 18Z and 01Z.
There is a 20 percent chance of thunderstorms through the TAF
period.
KBUR...Very low confidence in the 12Z TAF due variable low
cigs/vsbys assoc with moderate to heavy rain. There is a 20
percent chance of thunderstorms through the TAF period.
&&
.MARINE...16/440 AM.
...Very Dangerous Conditions Today...
A very dangerous storm system will bring strong south to southeast
winds, reduced visibilities due to moderate to heavy rain and
isolated thunderstorms to the waters today. The winds will continue
to increase through the day. These winds will create very steep
seas over 10 feet. These winds will weaken significantly Friday
night but steep seas will likely linger. Gusty NW winds should
form quickly NW of San Nicolas Island Saturday before gradually
diminishing Sunday.
The threat for isolated thunderstorms today across all waters
will shift to the south of Point Conception by Saturday morning
before the threat diminishes areawide.
High confidence in widespread strong Gale Force SE Winds on
Friday, with a 40 percent chance of exceeding Storm Force (48 KT).
Channels and passages between islands will likely see locally
enhanced winds. High confidence in a moderately large west to
northwest long period swell building in Saturday and Sunday as
well, which will create dangerous breaking waves near shore. Good
confidence of thunderstorms forming over the coastal waters
through early Saturday, but confidence is low in terms of timing,
severity and exact location.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 10 PM PST Sunday for zones
34-35-39>41-87. (See LAXCFWLOX).
Wind Advisory in effect until 4 PM PST this afternoon for
zones 34-36-39. (See LAXNPWLOX).
High Wind Warning in effect until 4 PM PST this afternoon for
zones 35-549-550. (See LAXNPWLOX).
Flash Flood Watch in effect through Saturday morning for
zones 35-36-38>41-44>46-52>54-59-87-88-547-549-550. (See LAXFFALOX).
High Wind Warning in effect until 10 PM PST this evening for
zones 37-38-51-52. (See LAXNPWLOX).
Wind Advisory in effect until 7 PM PST this evening for zones
40-41-44-45-547. (See LAXNPWLOX).
High Wind Warning in effect until 7 PM PST this evening for
zones 46-87-88. (See LAXNPWLOX).
Winter Storm Warning in effect until 11 AM PST Saturday for
zones 53-54. (See LAXWSWLOX).
Wind Advisory in effect from 10 AM this morning to 10 PM PST
this evening for zone 59. (See LAXNPWLOX).
PZ...Gale Warning in effect until 4 PM PST this afternoon for
zones 645-670-673. (See LAXMWWLOX).
Gale Warning in effect until 9 PM PST this evening for zones
650-655-676. (See LAXMWWLOX).
&&
.HAZARD POTENTIAL OUTLOOK...(SUN-THU)
High surf will impact area beaches Sunday and create hazards in
the surf zone.
&&
PUBLIC...Hall
AVIATION...Munroe
MARINE...Munroe
SYNOPSIS...Hall
weather.gov/losangelesThe Vandenberg AFB radar (KVBX), 47 km away, was scanning. The volume nearest the first event began at 22:31 UTC.
7 high wind, 5 flash flood, 2 winter storm. Local standard time, as filed.
The RAWS sensor at Lompoc Hills reported southerly wind gusts to 59 MPH.
The RAWS sensor at Tepusquet reported southerly winds with gusts to 63 MPH.
The sensor at Santa Cruz Island reported southerly winds with gusts to 74 MPH.
The sensor at Santa Rosa Island reported southerly winds with gusts to 76 MPH.
Strong southerly winds were reported in the Santa Clarita Valley. Some wind gusts from local RAWS stations include: Saugus (gust 66 MPH) and Newhall Pass (gust 61 MPH).
Heavy rain generated flash flooding at Santa Barbara airport. The airport was evacuated due to the flooding.
Heavy rain generated flash flooding as well as mud and debris flows in Ventura county. Highway 101 was closed in both directions near the Solimar burn area due to mud and debris flows.
The RAWS sensor at Malibu Hills reported southerly wind gusts to 59 MPH.
The RAWS sensor at Catalina Island reported southerly wind gusts to 60 MPH.
Heavy rain generated flash flooding as well as mud and debris flows in Los Angeles county around the Sand Fire burn scar. Significant mud and debris flows were reported. Twenty homes were evacuated and a two inch gas pipe snapped.
Heavy rain generated flash flooding in Ventura county near the community of Thousand Oak. In Wildwood Creek, there men were rescued from the water when the creek flooded.
Heavy rain generated flash flooding in Ventura county near the community of Camarillo. The heavy rain caused Conejo Creek to overflow its banks, flooding acres of agricultural land.
Winter storm conditions developed across the mountains of Los Angeles county. At the resort level, 12 to 24 inches of snow accumulated. Additionally, southerly winds gusting to 70 MPH were reported.
Winter storm conditions developed across the mountains of Ventura county. At the resort level, 8 to 16 inches of snow accumulated. Additionally, southerly winds gusting to 70 MPH were reported.
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, February 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: 682648, 682623, 682625, 682624, 682631, 682652, 682653, 682630, 682627, 682655, 682656, 682657, 682649, 682650.