Debris Flows and Flooding in California, January 9 to 10, 2018

Name: Debris Flows and Flooding in California, January 9 to 10, 2018
Start: 2018-01-09T03:13
End: 2018-01-10T21:00
Location: California

January 9 to 10, 2018 · NWS HNX · 10 events in 5 counties and zones

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $2,000
Crop damage: None recorded
Events: 10

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.

What happened

The episode as NWS HNX wrote it up.

January 2018 began with strong high pressure dominating over Central California. The high broke down by the 4th as a low pressure system pushed through Northern California bringing generally light precipitation to the area although a few locations picked up between a quarter and half an inch of rainfall. A few inches of snow fell above 8000 feet. Another low pressure pushed through Northern California on the morning of January 6 which brought half an inch to an inch of rain to much of Yosemite Park and Mariposa Counties with lesser amounts further south. Snow was mainly confined to elevations above 8000 feet with this system. A strong low pressure system moved southward off the Central California coast then pushed inland across Southern California between the morning of the 8th and the evening of the 9th. This system produced more substantial rainfall across the area with many locations in the Southern Sierra Nevada picking up between an inch and 2 inches of liquid precipitation. Strong southerly flow ahead of the system resulted in warming across the area ahead of the low and snow levels were above 10000 feet on the 8th when most of the precipitation fell. As the low moved closer to the area on the morning of the 9th, strong downslope winds developed in the south end of the San Joaquin Valley and the valley facing slopes of the Kern County Mountains. Winds along interstate 5 frequently gusted above 50 mph and the Grapevine Peak RAWS (which is on an exposed ridge top) gusted up to 94 mph. Areas of street flooding were reported in the Bakersfield area on the morning of the 9th, and some mudslides were produced by heavy rainfall closing roads at the intersection of Cuddy Valley Road and Mil Portero Highway west of Frazier Park and on Redrock Randsburg Road in the Kern County Desert. Colder air pushed into the area on the back side of the low lowering the snow levels to 5000 to 5500 feet where a few inches of snow fell in post-frontal showery precipitation. A few thunderstorms were observed in the south end of the San Joaquin Valley in the unstable airmass. The precipitation had ended by the morning of the 10th as the low moved out of the area. However, upslope low clouds lingered in much of the San Joaquin Valley and the lower foothills of the Southern Sierra Nevada and Kern County Mountains while dense fog slowed down traffic along Interstate 5 in the Grapevine area and along Highway 58 near Tehachapi. Most of the low cloud deck cleared out by the evening of the 10th.

What forecasters said that day

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 Hanford, CA wrote its last area forecast discussion before the first event at Jan 8, 3:00 PM PST, 12 hours 13 minutes earlier.

Area forecast discussion, Jan 8, 3:00 PM PST, 12 hours 13 minutes before

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
300 PM PST Mon Jan 8 2018

.SYNOPSIS...
A strong Pacific storm system will move into the area today
through Tuesday night bringing rain, snow and locally windy
conditions. High pressure will then rebuild over the region
beginning Wednesday for a return to dry weather.

&&

.DISCUSSION...
Stormy conditions continue across Central California as a upper
level low moving closer to shore with an associated cold front now
about 350 miles west of the Monterey Bay area. As the storm
approaches the West Coast, winds have been increasing as speeds
reach 20 to 30 mph. Areas around the Grapevine have reached speeds
of above 50 mph. Before the center of the storm moves closer to
shore around Tuesday morning the district will remain in the warm
sector today with mostly rain accumulating below the 7000 to 8000
foot level. In addition, the extensive cloud cover over the
district today has kept the atmosphere stable as the current
convective area remains offshore. However, even with the stable
air-mass, a subtropical moisture tap has allow the region to
receive from a tenth to a third of an inch across the valley floor
and from a half to almost an inch of precipitation across the
mountains in the last 24 hours. While models show the moisture be
tapered-off in the next 24 hours, satellite imagery show moisture
from an area near Hawaii still streaming toward Central
California. Therefore, will expect moderate to heavy precipitation
possible through Tuesday.

Models showing higher confidence in dropping the upper low toward
Southern California on Tuesday. The current trajectory has the
center of the low moving onshore near San Luis Obispo/Santa
Barbara Counties by midday Tuesday model instability increase
during the next 24 hours. While the potential for thunderstorms
will be greatest over Southern California, Central California
could be affected due to the trajectory of the upper low.
Therefore, will keep a mention of convective activity over Central
California on Tuesday from midday to early evening. At about this
time, models place the bulk of Tuesday's precipitation during the
convective event. Therefore, while the valley accumulation will
be spotty, additional orographic support will enhance mountain
precipitation accumulation. This extra support will allow the
Winter Storm Warning and potential Flash Flood Watch to remain in
effect for the higher terrain of the Sierra Nevada. In addition to
the possible convective lift, precip-water values from Vandenberg
and San Diego are currently at their max values climo-wise.
Therefore, the atmosphere is very moist with a potential for heavy
precipitation through at least Tuesday night.

By Wednesday morning and beyond, the upper level disturbance
pushes toward the Four Corners area with a strong northwesterly
flow in its wake. Therefore, while precipitation is expected to
diminish on Wednesday, strong surface winds from the Northwest
will provide good mixing and the prevention of valley fog. Yet, by
Wednesday afternoon, models place the next ridge axis just off the
West Coast which may exist over the region until the end of the
week. While models do show a disturbance riding over the ridge
pattern, will not expect that disturbance to affect the Central
California Interior. In addition, the weekend will see the ridge
rebound for a continuation of the dry pattern that may extend into
next Monday. Again, while Wednesday morning may not have the
potential for dense fog, the morning afterward will have a good
chance of very low visibility values.

&&

.AVIATION...
San Joaquin Valley...Precipitation overspreading the area with
local MVFR ceilings in the San Joaquin Valley and adjacent
foothills, wind gusts 35 kts along the Diablo Mountains and passes.

Sierra Nevada and Tehachapi Mountains...Areas of mountain
obscurations developing with high winds probable 35+ kts after 02z
Tuesday.

Kern County Desert...VFR conditions through 02Z Tuesday, rain
overspreading the area thereafter with local MVFR ceilings.

&&

.AIR QUALITY ISSUES...
None.

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
Flash Flood Watch through late tonight CAZ092>094-096-097.

Winter Storm Warning from 10 PM this evening to 10 PM PST
Tuesday CAZ096-097.

High Wind Warning until 7 AM PST Tuesday CAZ091-092-095.

High Wind Warning until 4 AM PST Tuesday CAZ089-090.

&&

public/synopsis...Molina
avn/fw...Andersen

weather.gov/hanford

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 flood, 2 high wind, 2 debris flow, 2 strong wind, 1 dense fog. Local standard time, as filed.

High Wind, Kern Cty Mtns

When: January 9, 3:13 AM PST
Where: Kern Cty Mtns forecast zone
Measured: 82 kt (94 mph) measured gust
Reported by: RAWS

The Grapevine Peak RAWS reported a peak wind gust of 94 mph.

Debris Flow, Kern

When: January 9, 7:04 AM PST
Where: Kern County, 7.7 mi WNW of Frazier Park to 7.67 mi WNW of Frazier Park
Cause: Heavy Rain
Reported by: Public
Coordinates: 34.843, -119.083

Public report of mudslide closing the intersection of Cuddy Valley Rd. and Mil Portero Hwy 8W Frazier Park.

Debris Flow, Kern

When: January 9, 8:19 AM PST
Where: Kern County, 1 mi NE of Cantil to 2.61 mi SSW of Saltdale
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 35.310, -117.957

California Highway Patrol reported flooding and debris across Redrock-Randsburg Rd. near Cantil and the road was closed to traffic.

Strong Wind, S Sierra Mtns

When: January 9, 10:12 AM PST
Where: S Sierra Mtns forecast zone
Measured: 43 kt (49 mph) estimated gust
Property damage: $1,000
Reported by: Law Enforcement

California Highway Patrol reported a downed tree blocking the roadway 6W Grant Grove.

Strong Wind, S Sierra Foothills

When: January 9, 10:14 AM PST
Where: S Sierra Foothills forecast zone
Measured: 43 kt (49 mph) estimated gust
Property damage: $1,000
Reported by: Law Enforcement

California Highway Patrol reported a downed large tree across the road 3S North Fork.

Flood, Kern

When: January 9, 11:00 AM PST
Where: Kern County, Bakersfield to 0.16 mi NNE of Bakersfield
Cause: Heavy Rain
Reported by: Social Media
Coordinates: 35.370, -119.000

Pictures indicating roadway flooding in downtown Bakersfield near the intersection on Union Ave. and Truxton Ave. were received on Facebook and Twitter.

Flood, Kern

When: January 9, 11:19 AM PST
Where: Kern County, 1.35 mi WNW of Bakersfield to 1.34 mi WNW of Bakersfield
Cause: Heavy Rain
Reported by: Broadcast Media
Coordinates: 35.380, -119.020

Pictures indicating roadway flooding on 23rd St. in downtown Bakersfield were received on Facebook and Twitter.

Flood, Kern

When: January 9, 11:22 AM PST
Where: Kern County, 1.15 mi W of Bakersfield
Cause: Heavy Rain
Reported by: Social Media
Coordinates: 35.370, -119.020

Pictures indicating the courthouse parking lot in Bakersfield was flooded were received on Facebook and Twitter.

Dense Fog, Kern Cty Mtns

When: January 10, 1:15 AM PST to 9:00 PM PST
Where: Kern Cty Mtns forecast zone
Reported by: AWOS

The Tehachapi AWOS reported visibility below a quarter mile and California Highway Patrol reported low visibility on Interstate 5 which slowed down traffic for much of the day as low level upslope flow produced low clouds which banked up on the valley facing slopes of the Tehachapi Mountains forming dense fog along Interstate 5 and State Route 58.

High Wind, Se Kern Cty Desert

When: January 10, 4:40 PM PST
Where: Se Kern Cty Desert forecast zone
Measured: 61 kt (70 mph) measured gust
Reported by: AWOS

The Mojave Airport AWOS reported a peak wind gust of 70 mph.

What these are

High Wind: Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.
Debris Flow: A fast-moving slurry of mud, rock and debris, usually on a slope soaked by heavy rain or stripped by a fire.
Strong Wind: Non-thunderstorm winds below high wind criteria that nonetheless caused damage or casualties.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
Dense Fog: Fog reducing visibility to a quarter mile or less, filed where it caused accidents or disruption.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in California in 2018 Every state in 2018 This day in weather history Warnings in California, January 2018

Sources

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: 727143, 727140, 727142, 727149, 727148, 727137, 727138, 727139, 727152, 727146.