California, 2020

Dense Fog in California, January 25, 2020

January 25, 2020 · NWS HNX · 2 events in 2 counties and zones

Although high pressure remained over the area, some high clouds pushed through and were able in inhibit the formation of widespread dense fog on the morning of January 25. However, a strip of dense fog formed in the center of the San Joaquin Valley along State Route 99 north of Fresno and impacted travel through Merced and Madera during the morning.

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
2

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.

Although high pressure remained over the area, some high clouds pushed through and were able in inhibit the formation of widespread dense fog on the morning of January 25. However, a strip of dense fog formed in the center of the San Joaquin Valley along State Route 99 north of Fresno and impacted travel through Merced and Madera during the morning. The fog completely 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 Jan 24, 7:02 PM PST, 8 hours 8 minutes earlier.

Area forecast discussion, Jan 24, 7:02 PM PST, 8 hours 8 minutes before
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Event by event

2 dense fog. Local standard time, as filed.

Dense Fog, Merced and Madera

When
January 25, 3:10 AM PST to 8:45 AM PST
Where
Merced and Madera forecast zone
Reported by
ASOS

Visibility below a quarter mile was reported in Merced and Madera.

Dense Fog, Western San Joaquin Valley

When
January 25, 7:29 AM PST to 8:03 AM PST
Where
Western San Joaquin Valley forecast zone
Reported by
ASOS

Visibility below a quarter mile was reported in Lemoore.

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, January 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 2026-09-30. Each event’s entry at NCEI: 866244, 866245.