Name: Dense Fog in California, February 4, 2006
Start: 2006-02-04T00:35
End: 2006-02-04T11:30
Location: California

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.

Visibilities on Central and Southern San Joaquin Valley roads dropped to as low as 100 to 200 feet just after midnight and persisted through the late morning on the 4th. A multiple vehicle accident occurred south of Fresno along Highway 41 before dawn with the dense fog a contributing factor.

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 Feb 3, 10:25 PM PST, 2 hours 10 minutes earlier.

Area forecast discussion, Feb 3, 10:25 PM PST, 2 hours 10 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
1025 PM PST FRI FEB 3 2006

UPDATE...ISSUED A DENSE FOG ADVISORY FOR THE CENTRAL AND
SOUTHERN SAN JOAQUIN VALLEY AS THE FOG RAPIDLY FORMED.

.SHORT TERM...FOR THE CENTRAL CALIFORNIA INTERIOR...MAIN FORECAST
CONCERN THIS EVENING IS FOG IN THE SAN JOAQUIN VALLEY AND JUST HOW
WIDESPREAD IT WILL GET. DEW POINTS ARE RUNNING INTO THE MID 50S AND
WITH THIS VERY MOIST ATMOSPHERE, VIRTUALLY NO CLOUDS ALOFT AND
LIGHT WINDS, RAPID FOG FORMATION SHOULD OCCUR LATER THIS EVENING.
HAVE UPDATED THE GRIDS FOR AREAS OF FOG. WILL HOLD OFF ON ISSUING A
DENSE FOG ADVISORY FOR THE TIME BEING, BUT IT SHOULD BE NEEDED
LATER. AS FOR THE INCOMING PACIFIC SYSTEM, SATELLITE IMAGERY SHOWS
IT HEADING WELL NORTH OF THE AREA AS THE RIDGE IS STRONG. LATEST
RUN OF THE GFS AND NAM MODELS STILL BRINGS A SLIGHT THREAT OF
PRECIPITATION TO THE FAR NORTHERN PART OF THE FORECAST AREA
SATURDAY. I HAVE DECIDED TO LEAVE THE SLIGHT CHANCE IN GRIDS,
HOWEVER I WOULDNT BE SURPRISED IF NO ONE GETS ANY RAIN OR SNOW FROM
THIS SYSTEM. IN THE POST TROUGH NORTHWEST FLOW, LOW LEVEL MOISTURE
WILL POUR INTO THE SAN JOAQUIN VALLEY AND I EXPECT THE USUAL STRATUS
TO FORM OVER THE SOUTH END AND EAST SIDE, THE FOOTHILLS AND SAN
JOAQUIN VALLEY FACING SLOPES OF THE KERN MOUNTAINS. THIS SHOULD
PERSIST INTO EARLY SUNDAY MORNING BEFORE AN INCREASING NORTH TO
NORTHEAST FLOW CLEARS IT OUT. RIDGING IS PROGGED TO REMAIN OVER THE
AREA INTO MONDAY FOR CONTINUED DRY WEATHER.

.LONG TERM...FOR MONDAY NIGHT THROUGH FRIDAY...MODELS SIMILAR IN
BUILDING MEAN UPPER RIDGE OVER THE WEST COAST MON NITE AND
TUES...THEN KEEPING IT RELATIVELY STATIONARY REMAINDER OF THE WEEK.
HOWEVER MODELS DO DIFFER QUITE A BIT IN THE HEIGHT FIELDS ACROSS
CENTRAL CA. FOR TEMPS...USED BASICALLY MIDDLE OF THE ROAD APPROACH
BETWEEN LAST NIGHTS COOLER MEX MOS NUMBERS AND THIS MORNINGS WARMER
VALUES. THIS KEEPS MOST TEMPS THRU THE PERIOD A FEW DEGS ABOVE
NORMAL FOR EARLY FEB...AND VERY LITTLE IN THE WAY OF CLOUDS. HOWEVER
TEMPS IN THE SJV WILL DEPEND ON AMOUNT AND PERSISTENCE OF ANY FOG.

&&

.AVIATION...MVFR DUE TO VIS WITH LOCAL IFR IN CIGS IN THE SAN
JOAQUIN VALLEY...BECOMING WIDESPREAD IFR IN FOG/CIGS AFTER 06Z.
ELSEWHERE VFR. FOR SPECIFIC DETAILS...PLEASE REFER TO TAFS FOR
KMCE...KFAT AND KBFL.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY FOR THE
CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY UNTIL 1000 AM PST
SATURDAY.

&&

WWW.WEATHER.GOV/HANFORD /USE ALL LOWER CASE/

DUDLEY/BINGHAM

Event by event

4 dense fog. Local standard time, as filed.

Dense Fog, E Central S.J. Valley

When: February 4, 12:35 AM PST to 11:30 AM PST
Where: E Central S.J. Valley forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Dense Fog, Sw S.J. Valley

When: February 4, 4:53 AM PST to 11:30 AM PST
Where: Sw S.J. Valley forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Dense Fog, Se S.J. Valley

When: February 4, 4:53 AM PST to 11:30 AM PST
Where: Se S.J. Valley forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Dense Fog, W Central S.J. Valley

When: February 4, 6:00 AM PST to 11:30 AM PST
Where: W Central S.J. Valley forecast zone
Reported by: OFFICIAL NWS OBS.

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 2006 Every state in 2006 This day in weather history Warnings in California, February 2006

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: 5490092, 5490093, 5490094, 5490091.