High Wind in California, December 17, 2020

Name: High Wind in California, December 17, 2020
Start: 2020-12-17T11:10
End: 2020-12-17T15:14
Location: California

December 17, 2020 · NWS HNX · 3 events in 2 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 3

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.

An upper level low pressure system moved eastward across northern California on December 17 which pushed a cold front through central California during the morning and early afternoon hours. This front provided for a brief period of light precipitation across much of the area. Yosemite Park was hit the hardest once again with several stations in the park measuring between half and inch and an inch of liquid precipitation. The precipitation fell as snow above 6000 feet and several high elevation stations picked up between 5 and 9 inches of new snowfall. Further south, much of the Sierra Nevada and adjacent foothills measured between a quarter inch to a half inch of liquid precipitation while the San Joaquin Valley measured between a tenth of an inch and a quarter inch of rainfall near Merced and Madera while the remainder of the valley and the mountains and deserts of Kern County received between trace amounts and a tenth of an inch of rainfall. Just as with the previous two systems, the main impact from this system was a period of increased winds across the mountains and deserts of Kern County. Several stations measured gusts between 40 and 50 mph during the early afternoon hours while a few low impact indicator sites measured gusts exceeding 60 mph. The winds diminished in the evening as the system moved further away for the area.

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 17, 3:30 AM PST, 7 hours 40 minutes earlier.

Area forecast discussion, Dec 17, 3:30 AM PST, 7 hours 40 minutes before

Area Forecast Discussion
National Weather Service Hanford CA
330 AM PST Thu Dec 17 2020

.SYNOPSIS...A storm system will bring wet weather to much
of the district today along with gusty winds in the Kern county
mountains and desert this afternoon and evening. A clearing trend
will occur in the wake of this system tonight. A ridge of high
pressure will build into California by Friday and remain in
control through the Christmas holiday. Mostly clear skies can be
expected during this time with areas of late night and morning
fog in the San Joaquin Valley.

&&

.DISCUSSION...
Regional radar and satellite loops are showing the well advertised
cold front just entering Merced county as of this writing. The
front will be passing through CENCAL this morning with some
possible clearing in the SJV later this afternoon. Unfortunately,
there is not much lower elevation rain and mountain snow with the
system. There will be enough to wet the roads, but as you get
into Kern county, it will be drier. We are expecting winds to pick
up across the Kern County mountains later today as the front
pushes through.

We have a winter weather advisory out for the Yosemite National
Park area above 5500 feet for snow up to 9 inches through this
afternoon. Cold air behind the system will allow our temepratures
to drop below freezing overnight for the next several days into
early next week. The active storm track will remain well to our
north as a ridge of high pressure returns and will shun away any
systems that try to move into CENCAL through the forecast period
and beyond. We will have a system move through Nevada on Tuesday
night that could bring some winds across parts of the CENCAL
interior. A full amplitude ridge will block any weather systems
along the west coast through the Christmas holiday week. A closed
low center off of Baja will set up a Rex Block pattern later next
week. Temperatures will try to moderate some by the end of the
forecast period with dry conditions expected.

&&

.AVIATION...
IFR conditions can be expected in the Sierra with mountain
obscuration in precipitation through this evening. MVFR with
areas of IFR can be expected along the west slope of the Sierra
and the north facing slopes of the Kern county mountains by 17z
Thursday and continue into Friday morning. Wind gusts above 35
knots are likely through and below the Kern county mountain passes
by 19z Thursday. VFR conditions can be expected elsewhere over
the central California interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...
None.

&&

.CERTAINTY...

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

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 until 4 PM PST this afternoon for CAZ192.

Wind Advisory from noon today to 9 PM PST this evening for
CAZ195>199.

&&

public...JDB
aviation....Molina

weather.gov/hanford

Event by event

3 high wind. Local standard time, as filed.

High Wind, Lake Isabella

When: December 17, 11:10 AM PST
Where: Lake Isabella forecast zone
Measured: 52 kt (60 mph) measured gust
Reported by: RAWS

The Bear Peak RAWS measured a peak wind gust of 60 mph.

High Wind, Tehachapi Area

When: December 17, 2:27 PM PST
Where: Tehachapi Area forecast zone
Measured: 61 kt (70 mph) measured gust
Reported by: RAWS

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

High Wind, Tehachapi Area

When: December 17, 3:14 PM PST
Where: Tehachapi Area forecast zone
Measured: 68 kt (78 mph) measured gust
Reported by: RAWS

The Jawbone Canyon RAWS measured a peak wind gust of 78 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.

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

The same day elsewhere

Every storm in California in 2020 Every state in 2020 This day in weather history Warnings in California, December 2020

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: 924732, 924733, 924734.