California, 2020

Dense Fog in California, December 22, 2020

December 22, 2020 · NWS HNX · 1 event in 1 county or zone

Low level upslope clouds which resulted from a passing trough over northern California banked up over the Tehachapi Valley during the evening of December 22 resulting in dense fog in the Tehachapi area and travel disruptions along State Route 58. The fog dissipated by late evening and skies cleared out during the morning of December 23.

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
1

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.

Low level upslope clouds which resulted from a passing trough over northern California banked up over the Tehachapi Valley during the evening of December 22 resulting in dense fog in the Tehachapi area and travel disruptions along State Route 58. The fog dissipated by late evening and skies cleared out during the morning of December 23.

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 22, 4:39 PM PST, 3 hours 56 minutes earlier.

Area forecast discussion, Dec 22, 4:39 PM PST, 3 hours 56 minutes before
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Event by event

1 dense fog. Local standard time, as filed.

Dense Fog, Tehachapi Area

When
December 22, 8:35 PM PST to 11:55 PM PST
Where
Tehachapi Area forecast zone
Reported by
AWOS

Tehachapi reported visibility below a quarter mile.

What these are

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

More

Every storm in California in 2020Every state in 2020This day in weather historyWarnings 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 2026-10-01. Each event’s entry at NCEI: 925638.