Debris Flows and Flood in California, December 31, 2005

Name: Debris Flows and Flood in California, December 31, 2005
Start: 2005-12-31T09:20
End: 2005-12-31T17:00
Location: California

December 31, 2005 · NWS HNX · 4 events in 3 counties and zones

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

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.

Locally heavy rain contributed to numerous rock and mudslides in the lower elevations of the Southern Sierra Nevada and Tulare County foothills as well as the far western area of Merced County on the Coast Range at Pacheco Pass. California Highway Patrol reported that Highway 140 at Savages Trading Post had water and debris washed over the bridge along with a rockslide farther up the road below Yosemite National Park. In the Madera County area a mudslide occurred near Bass Lake, and in the Tulare County a large boulder blocked lanes of State Highway 190. Rainfall amounts included 0.40" at Madera, 0.36" at Merced, 0.35" at Hanford, 0.24" at Fresno, and only 0.11" at Bakersfield.

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 31, 2:10 AM PST, 7 hours 10 minutes earlier.

Area forecast discussion, Dec 31, 2:10 AM PST, 7 hours 10 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
210 AM PST SAT DEC 31 2005

.SHORT TERM...HANFORD RADAR SHOWS INCREASING COVERAGE OF ECHOES OVER
THE NORTH, WITH THE SIERRA AND FOOTHILLS HAVING HEAVY PRECIPITATION.
OVER THE SAN JOAQUIN VALLEY ECHOES HAVE BEEN SPOTTY AT TIMES
BUT THE MAIN RAIN STILL REMAINS TO THE NORTH AND OVER THE FOOTHILLS
AND SIERRA. VERY FAST FLOW IS NOTED ON THE VAD WIND PROFILE AT
ELEVATIONS ABOVE 10000 FEET AND THIS IS LIKELY ENHANCING THE
PRECIPITATION RATES IN THE SIERRA. INTERESTINGLY ENOUGH, TO THE
WEST AND NORTH, VERY FEW ECHOES ARE NOTED ON RADAR AND THIS IS
INDICATIVE OF SOME DOWNSLOPING FROM THE COASTAL MOUNTAINS. THE MAIN
FORECAST PROBLEM THIS MORNING IS THE TIMING OF THE RAIN ONSET OVER
AREAS SOUTH OF FRESNO. SATELLITE IMAGERY SHOWS THE BAROCLINIC ZONE
SLOWLY PUSHING SOUTHEAST AND AT THE CURRENT RATE OF MOVEMENT, AREAS
OVER KERN COUNTY ARE GOING TO HAVE TO WAIT QUITE A WHILE FOR ANY
PRECIPITATION. MONTEREY RADAR IS FINALLY BEGINNING TO SHOW THE RAIN
BAND ASSOCIATED WITH THE BAROCLINIC ZONE (FRONT, BUT IT IS STILL
WELL OFFSHORE.  THE LATEST HIGH RESOLUTION NAM MODEL PROGS NO
MEASURABLE RAIN AT BAKERSFIELD UNTIL THIS AFTERNOON AND THIS MATCHES
UP WELL WITH THE RADAR DATA. WILL HAVE TO REWORD THE ZONE
FORECASTS TO REFLECT THIS SLOWER TIMING.

WINDS TODAY WILL BE A FORECAST PROBLEM ALSO. OVER THE KERN COUNTY
DESERT AREAS LATEST MOS GUIDANCE FROM THE NAM MODELS SUGGESTS
ADVISORY LEVEL CONDITIONS AND THIS SEEMS LIKELY AS A STRONG PRESSURE
GRADIENT COMBINES WITH STRONG MID LEVEL WINDS. SWING SHIFT REALLY
BEEFED UP THE WINDS IN THE GRIDS AND I WILL ISSUE A WIND ADVISORY FOR
ZONES 95, 98 AND 99 FOR LATE THIS MORNING AND AFTERNOON. AS FOR
THE WINTER STORM WARNING. RADAR SHOWS HEAVY PRECIPITATION IN THE
SIERRA, AND THE MESOWEST SHOWS HOURLY RAINFALL RATES RUNNING AROUND
0.25 PER HOUR AT GIN FLAT, CHILKOOT MEADOW AND GREEN MOUNTAIN AS THE
OROGRAPHICS ARE IDEAL. MESOWEST SURFACE DATA FROM THE SIERRA ALSO
SHOWS THE SNOW LEVEL AT AROUND 8000 FEET AND IT IS LIKELY TO STAY
THAT HIGH UNTIL LATER TODAY. HIGHER ELEVATIONS ARE UNDOUBTEDLY
GETTING SOME VERY HEAVY SNOW AND WIND. WILL HAVE TO MONITOR THE
FOOTHILLS AND LOWER SIERRA SLOPES FOR POSSIBLE SMALL STREAM FLOODING
TODAY AS LATEST MODEL GUIDANCE AND QPF FORECASTS FROM THE RIVER
FORECAST CENTER IN SACRAMENTO SUGGEST AS MUCH AS 6 INCHES OF RAIN MAY
FALL IN THE YOSEMITE AREA BY LATE TODAY. THIS VERY WET SYSTEM AND
WINDY SYSTEM IS PROGGED TO MOVE EAST OF THE AREA TONIGHT AND THIS
SHOULD BRING THE PRECIPITATION TO A BRIEF END. WEAK RIDGING IS
FORECAST TO MOVE OVER THE DISTRICT LATE SATURDAY NIGHT AND SUNDAY,
HOWEVER THE NEXT SEEMINGLY WETTER AND DEEPER PACIFIC SYSTEM SHOULD
ARRIVE SUNDAY NIGHT AND MONDAY WITH THE PROSPECTS OF MORE HEAVY RAIN,
SNOW AND WIND. THE TRAJECTORY OF THIS STORM IS A LITTLE FARTHER SOUTH
AND IT MAY TARGET THE SOUTHERN PART OF THE FORECAST AREA, ALTHOUGH
ALL AREAS WILL SEE SIGNIFICANT PRECIPITATION.  A WINTER STORM WATCH
WILL BE ISSUED LATER TODAY FOR THIS SECOND STORM.

.LONG TERM...FOR MONDAY NIGHT THROUGH FRIDAY...MEDIUM RANGE
MODELS IN GOOD AGREEMENT DURING THE PERIOD. A PACIFIC STORM SYSTEM
WILL EXIT CENTRAL CALIFORNIA LATE MONDAY NIGHT. SHOWER ACTIVITY
SHOULD DIMINISH MONDAY NIGHT. A LARGE UPPER LEVEL RIDGE WILL BUILD
OVER THE WESTERN U.S TUESDAY AND WEDNESDAY. THIS WILL BRING DRY
CONDITIONS ACROSS CENTRAL CALIFORNIA. MOUNTAIN AND DESERT LOCALES
WILL HAVE MILD TEMPERATURES...WHILE FOG FORMATION IN THE SAN JOAQUIN
VALLEY WILL KEEP TEMPERATURES A BIT COOLER. THE RIDGE THEN AMPLIFIES
AND SHIFTS TOWARDS THE INTERIOR WEST THURSDAY AND FRIDAY. THIS WILL
ALLOW THE STORM TRACK TO SHIFT INTO THE PACIFIC NORTHWEST AND NORTH
CALIFORNIA LATE IN THE PERIOD.

&&

.AVIATION...A PACIFIC STORM WILL AFFECT THE REGION THROUGH TONIGHT.
THIS WILL RESULT IN  MOUNTAIN OBSCURATION ACROSS THE SIERRA AND
TEHACHAPI MOUNTAINS THROUGH 12Z SUNDAY. AREAS OF RAIN AND GUSTY
WINDS OVER THE SAN JOAQUIN VALLEY WILL RESULT IN WIDESPREAD MVFR
CEILINGS THROUGH 06Z WITH LOCAL IFR VISIBILITIES IN HEAVIER RAIN
SHOWERS. SEE TAFS FOR KFAT...KBFL...KMCE FOR GREATER DETAILS.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING FOR THE
     SIERRA NEVADA FROM YOSEMITE TO THE KERN COUNTY LINE THROUGH
     10 PM PST TONIGHT.
     ...WIND ADVISORY FOR THE KERN COUNTY MOUNTAINS AND DESERT FROM
     10 AM PST UNTIL 6 PM PST THIS EVENING.

&&

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

DUDLEY/MV

Hazardous weather outlook, Dec 31, 5:00 AM PST, 4 hours 20 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
500 AM PST SAT DEC 31 2005

CAZ096-097-011300-
SIERRA NEVADA FROM YOSEMITE TO KINGS CANYON-TULARE COUNTY MOUNTAINS-
500 AM PST SAT DEC 31 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE SIERRA NEVADA FROM
YOSEMITE TO KINGS CANYON...AND THE TULARE COUNTY MOUNTAINS.

.DAY ONE...TODAY

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 10 PM PST THIS
EVENING. PLEASE REFER TO THE LATEST WINTER WEATHER MESSAGE /WWUS46
KHNX/ FOR FURTHER DETAILS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THEIR NATIONAL WEATHER SERVICE OFFICE.

CAZ095-098-099-011300-
KERN COUNTY MOUNTAINS-INDIAN WELLS VALLEY-
SOUTHEASTERN KERN COUNTY DESERT-
500 AM PST SAT DEC 31 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE SOUTHEASTERN KERN COUNTY.

.DAY...TODAY

WIND ADVISORY IN EFFECT FROM 10 AM THIS MORNING TO 6 PM PST THIS
AFTERNOON. PLEASE REFER TO THE LATEST WEATHER MESSAGE SFONPWHNX
/WWUS76 KHNX/ FOR FURTHER DETAILS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THEIR NATIONAL WEATHER SERVICE OFFICE.

CAZ089>094-011300-
WEST CENTRAL SAN JOAQUIN VALLEY-EAST CENTRAL SAN JOAQUIN VALLEY-
SOUTHWESTERN SAN JOAQUIN VALLEY-SOUTHEASTERN SAN JOAQUIN VALLEY-
MARIPOSA MADERA AND FRESNO COUNTY FOOTHILLS-TULARE COUNTY FOOTHILLS-
500 AM PST SAT DEC 31 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE CENTRAL AND SOUTHERN SAN
JOAQUIN VALLEY...AND ADJACENT FOOTHILLS.

.DAY ONE...TODAY

THERE IS A CHANCE FOR THUNDERSTORMS THIS AFTERNOON. SOME STORMS MAY
PRODUCE HEAVY RAINFALL...GUSTY WINDS...SMALL HAIL...AND FREQUENT
LIGHTNING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THEIR NATIONAL WEATHER SERVICE OFFICE.

TLM

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 debris flow, 1 flood. Local standard time, as filed.

Debris Flow, S Sierra Foothills

When: December 31, 9:20 AM PST to 3:30 PM PST
Where: S Sierra Foothills forecast zone
Reported by: LAW ENFORCEMENT

Debris Flow, W Central S.J. Valley

When: December 31, 9:35 AM PST to 3:00 PM PST
Where: W Central S.J. Valley forecast zone
Reported by: LAW ENFORCEMENT

Debris Flow, Tulare Cty Foothills

When: December 31, 11:20 AM PST to 3:00 PM PST
Where: Tulare Cty Foothills forecast zone
Reported by: LAW ENFORCEMENT

Flood, S Sierra Foothills

When: December 31, 11:50 AM PST to 5:00 PM PST
Where: S Sierra Foothills forecast zone
Reported by: LAW ENFORCEMENT
Coordinates: 41.617, -122.550

What these are

Debris Flow: A fast-moving slurry of mud, rock and debris, usually on a slope soaked by heavy rain or stripped by a fire.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

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, December 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: 5489195, 5489196, 5489197, 5489198.