Dense Fog in California, February 2, 2005

Name: Dense Fog in California, February 2, 2005
Start: 2005-02-02T03:15
End: 2005-02-02T10:00
Location: California

February 2, 2005 · NWS HNX · 3 events in 3 counties and zones

Numerous aviation sites with less than 1/4 mile visibility plus satellite data confirms widespread nature of dense fog on the morning of the 2nd.

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.

Numerous aviation sites with less than 1/4 mile visibility plus satellite data confirms widespread nature of dense fog on the morning of the 2nd.

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 1, 9:30 PM PST, 5 hours 45 minutes earlier.

Area forecast discussion, Feb 1, 9:30 PM PST, 5 hours 45 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
930 PM PST TUE FEB 1 2005

.SHORT TERM...FOR THE CENTRAL CALIFORNIA INTERIOR...PRIMARY CONCERN
REMAINS GUSTY WINDS OVER HIGHER PEAKS AND RIDGES AS APPROX 100 KT
JET SHIFTS SOUTH ALONG THE SIERRA. THOUGH WIND SPEEDS HAVE DECREASED
SLIGHTLY AT SEVERAL LOCATIONS EARLY THIS EVENING...SUBSIDENCE WILL
AGAIN INCREASE AS STRONG VORT OVER THE SE KERN DESERT MOVES SW
AROUND 40 KTS. WILL THEREFORE MAINTAIN CURRENT FORECASTS OF LOCAL
GUSTS TO 50 MPH OVER THE HIGH SIERRA AND KERN MTNS OVERNIGHT. WILL
ALSO PREPARE MINOR GRID AND ZONE UPDATES TO INTRODUCE STRONGER
SPEEDS TO THE SIERRA FOOTHILLS AND THE KERN DESERTS.

FOR THE REMIANDER OF THE CWA...SOME JET-ASSOCIATED HIGH CLOUDS MAY
AFFECT THE REGION AT TIMES...OTHERWISE SKIES WILL REMAIN CLEAR. NO
OTHER UPDATES REQUIRED AT THIS TIME.

.LONG TERM...FOR FRIDAY NIGHT THROUGH TUESDAY...THE MEDIUM-RANGE
MODELS CONTINUE IN GOOD AGREEMENT THROUGH SATURDAY...KEEPING THE
UPPER-LEVEL RIDGE OVER NORTHERN CALIFORNIA AND A WEAK UPPER-LEVEL
LOW OVER NORTHERN BAJA CALIFORNIA. THIS PATTERN SUPPORTS DRY WEATHER
OVER THE CENTRAL CALIFORNIA INTERIOR WITH A CONTINUATION OF THE
OFFSHORE FLOW. WILL CONTINUE WITH LATE NIGHT AND MORNING FOG IN THE
SAN JOAQUIN VALLEY. ELSEWHERE EXPECT RELATIVELY MILD AFTERNOON TEMPS
EACH DAY WITH GENERALLY CLEAR SKIES FRIDAY AND SOME HIGH CLOUDS
MOVING THROUGH SATURDAY.

THE MODELS ARE BEGINNING TO COME INTO BETTER AGREEMENT WITH THE
UPPER-LEVEL SHORT-WAVE DROPPING THROUGH THE PACIFIC NORTHWEST AND
CARVING A TROUGH BACK INTO EASTERN CALIFORNIA...PUSHING THE RIDGE
AXIS WESTWARD INTO THE PACIFIC. THE GFS DOES NOT DIG THE TROUGH AS
DEEPLY INTO CALIFORNIA AS THE ECMWF AND UKMET...AND HAS A SHARP 850-
700-MB RELATIVE HUMIDITY GRADIENT ALONG THE SOUTHERN SIERRA NEVADA
WITH THE MOIST AIR DAMMED TO THE EAST. THE GFS ALSO HAS DRIER AIR
ABOVE 700 MB...AND A 500-MB VORTICITY MINIMUM OVER THE CENTRAL SAN
JOAQUIN VALLEY AT 12Z SUNDAY. FOR THESE REASONS...PREFER TO KEEP
SUNDAY DRY ON OUR SIDE OF THE SOUTHERN SIERRA NEVADA CREST FOR NOW
BUT HAVE INCREASED CLOUDS ALONG AND NEAR THE CREST.

THE GFS AND DGEX BUILD THE UPPER-LEVEL RIDGE BACK INTO CALIFORNIA
MONDAY AND TUESDAY. WITH A STABLE AIRMASS RETURNING ALOFT...HAVE
GONE WITH A RETURN OF NIGHT AND MORNING VALLEY FOG...WITH MOSTLY
CLEAR SKIES ELSEWHERE.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

Event by event

3 dense fog. Local standard time, as filed.

Dense Fog, Se S.J. Valley

When: February 2, 3:15 AM PST to 10:00 AM PST
Where: Se S.J. Valley forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Dense Fog, W Central S.J. Valley

When: February 2, 5:55 AM PST to 10:00 AM PST
Where: W Central S.J. Valley forecast zone
Reported by: OFFICIAL NWS OBS.

Dense Fog, Sw S.J. Valley

When: February 2, 5:55 AM PST to 10:00 AM PST
Where: Sw S.J. Valley forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

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

Every storm in California in 2005 Every state in 2005 This day in weather history Warnings in California, February 2005

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: 5442186, 5442184, 5442185.