High Wind and Dense Fog in California, December 25, 2018

Name: High Wind and Dense Fog in California, December 25, 2018
Start: 2018-12-25T03:14
End: 2018-12-25T08:35
Location: California

December 25, 2018 · NWS HNX · 4 events in 3 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 4

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.

A low pressure system moved through central California during the evening of December 24 and the morning of December 25. The Christmas Storm produced half and inch to an inch of liquid precipitation across much of the Southern Sierra Nevada while most of the San Joaquin Valley picked up between one and three tenths of and inch of rain while the Tehachapi Mountains picked up between a quarter to half an inch of liquid precipitation. The precipitation fell mainly as snow above 6000 feet, but amounts were generally light. A few stations along the southern Sierra crest picked up between 4 and 6 inches of new snow. This system also produced strong winds on Christmas morning over the Kern County Mountains and deserts where several locations reported gusts exceeding 40 mph while a few low impact indicator sites measured gusts near 70 mph. Finally, as winds diminished behind the system in the San Joaquin Valley, area of dense fog formed toward daybreak near Fresno and Porterville; but the fog dissipated by late morning.

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 Dec 24, 8:19 PM PST, 6 hours 55 minutes earlier.

Area forecast discussion, Dec 24, 8:19 PM PST, 6 hours 55 minutes before

Area Forecast Discussion...UPDATED
National Weather Service San Joaquin Valley - Hanford CA
819 PM PST Mon Dec 24 2018

.UPDATE...Updated AVIATION section.

&&

.SYNOPSIS...A low pressure system will exit the region early
Tuesday morning. Areas of precipitation can be expected overnight
across central California. Moderate to heavy snow will fall over
the high Sierra. As the system moves away early Christmas, wind
speeds will increase in the typical wind prone areas, especially
across the Kern County mountains on Tuesday. It should be clear
and cool Tuesday night into early Wednesday.

&&

.DISCUSSION...Advertised system still on track for this evening
across central California. Mid level clouds have already spilled
down from northern California and lower levels to moisten this
evening. This is still a quick moving system/trough with the 7H
low pretty much over the San Joaquin Valley by 09Z Tuesday. Most
of region also under left front quadrant of upper level jet
carving trough over the western US through Christmas Day.
Therefore, PoP forecast will be high this evening into tonight
along and just behind surface cold front.

The models keep this system and energy moving quickly on Christmas
Day. In fact, Relative Humidity fields show sharp value decrease
by late Tuesday morning on backside of jet, or downward forcing
region. Atmosphere to dry out with generally sunny sky by
afternoon. The exception will be the higher foothills and
mountains. Small chance of light snow or flurries will continue
above 5K feet. But even this should end by evening on Tuesday.

Otherwise, it should be clear Tuesday night with patchy late night
fog possible across the San Joaquin Valley. Not confident on
development of fog behind system with good mixing in the boundary
layer Tuesday night and Wednesday. In fact, airmass not conducive
for fog the next few nights, although cannot rule out patchy
dense fog in spots.

Regardless, heights aloft build Tuesday night and Wednesday before
next upstream trough digs into the Pacific Northwest. Next system
will have little impact for most of this forecast area with its
best dynamics and moisture going east of the Sierra Nevada range
Thursday into Friday. Will keep lower elevations dry and cool for
the rest of this holiday week. The latest GFS continues to project
a tightening northeast-southwest oriented gradient for the Friday
evening into Saturday morning period, due to the digging of the
upper-level trough to our east/southeast. So, the potential for a
brief Mono-type wind event remains over the Sierra and the prone
areas in the foothills. However, the Euro model also continues to
depict a mainly northerly flow. Will continue to monitor for this
possibility with additional model runs.

&&

.AVIATION...Conditions turning to IFR/LIFR through 12Z Tuesday
across most of central California with incoming storm. Ceiling
will lower this evening with precipitation and mountain
obscuration through Tuesday morning. Additionally, isolated
thunderstorms are possible between through 06z Tuesday. Otherwise,
VFR conditions will return to the San Joaquin Valley by Tuesday
afternoon. Northwest wind will increase most areas during this
time, especially gusty over the higher mountain passes.

&&

.AIR QUALITY ISSUES...
On Tuesday December 25 2018...Fireplace/Wood Stove Burning Status
is: No Burning Unless Registered in Kern and Tulare Counties.
Further information is available at Valleyair.org

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is medium.
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.html for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
Winter Weather Advisory from 7 PM this evening to 11 AM PST
Tuesday CAZ097.

Wind Advisory from 9 PM this evening to 9 PM PST Tuesday
CAZ095-097>099.

Winter Storm Warning from 5 PM this afternoon to 10 AM PST
Tuesday CAZ096.

&&

public...Lynott
avn/fw...Lynott
synopsis...Lynott

weather.gov/hanford

Event by event

2 high wind, 2 dense fog. Local standard time, as filed.

High Wind, Kern Cty Mtns

When: December 25, 3:14 AM PST
Where: Kern Cty Mtns forecast zone
Measured: 63 kt (72 mph) measured gust
Reported by: RAWS

The Jawbone Canyon RAWS reported a peak wind gust of 73 mph.

High Wind, Kern Cty Mtns

When: December 25, 5:27 AM PST
Where: Kern Cty Mtns forecast zone
Measured: 61 kt (70 mph) measured gust
Reported by: RAWS

The Bird Springs Pass RAWS reported a peak wind gust of 70 mph.

Dense Fog, E Central S.J. Valley

When: December 25, 5:50 AM PST to 8:35 AM PST
Where: E Central S.J. Valley forecast zone
Reported by: ASOS

Visibility below a quarter mile was reported in Fresno.

Dense Fog, Se S.J. Valley

When: December 25, 7:00 AM PST to 7:30 AM PST
Where: Se S.J. Valley forecast zone
Reported by: AWOS

Visibility below a quarter mile was reported in Porterville.

What these are

High Wind: Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.
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, December 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: 790658, 790659, 790656, 790657.