California, 2006

Debris Flow in California, April 29 to 30, 2006

April 29 to 30, 2006 · NWS HNX · 1 event in 1 county or zone

1 debris flow, as filed by the National Weather Service.

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 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 Apr 29, 1:45 AM PST, 4 hours 15 minutes earlier.

Area forecast discussion, Apr 29, 1:45 AM PST, 4 hours 15 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
245 AM PDT SAT APR 29 2006

.SHORT TERM...WARM TEMPERATURES INLAND AND AN APPROACHING SHORTWAVE
TROUGH HAVE REALLY PUMPED UP THE MARINE LAYER ALONG THE COAST.
MARINE LAYER DEPTH AT FORT ORD IS RUNNING AROUND 2200 FEET AND THE
STRATUS IS PUSHING THROUGH PACHECO PASS. COOLER AIR MADE AN
INTRUSION INTO WESTERN MERCED COUNTY AND WITH THE TROUGH APPROACHING
THE COAST AND AN ONSHORE GRADIENT, I EXPECT SOME SOUTHWARD INTRUSION
TODAY OF THE MARINE AIR. WILL OPT TO LOWER MAXES OVER AREAS NORTH OF
FRESNO WITH MERCED COUNTY THE COOLEST. MODELS AGREE IN KEEPING A
A RIDGE OVER THE WEST COAST WITH WEAK SHORTWAVES MOVING OVER THE
RIDGE.  NORMALLY THE MARINE AIR WILL SEEP SOUTH INTO KERN COUNTY AND
BY SUNDAY BAKERSFIELD AND THE SOUTH VALLEY WILL COOL JUST A TAD. ON
MONDAY, ALL MARINE EFFECTS WILL BE GONE AND WARMING WILL OCCUR.
STILL WATCHING THE AFFECTS OF WARMER MOUNTAIN TEMPERATURES ON THE
SNOWMELT RATE. THE MERCED RIVER IN YOSEMITE PARK IS UP ANOTHER FOOT
(7.9 FEET AT POHONO BRIDGE) OVER LAST NIGHT AND THE CURRENT ESF
(FLOOD PRODUCT) HANDLES THE SITUATION WELL. OTHER RIVERS AND STREAMS
SHOULD SEE RISES TODAY THROUGH MONDAY.

.LONG TERM...FOR MONDAY NIGHT THROUGH FRIDAY...THE MAJORITY OF THE
MEDIUM RANGE MODELS INDICATE THE UPPER RIDGE RETROGRADING OFFSHORE
DURING THE MIDDLE OF NEXT WEEK WHILE AN UPPER TROUGH DROPS INTO THE
INTERMOUNTAIN WEST...ALTHOUGH THE MODELS DO HAVE THEIR DIFFERENCES
ON THE TIMING AND AMPLITUDE OF THE TROUGH AS IT DROPS SOUTHWARD. A
NOTICEABLE EXCEPTION IS THE 00Z GEM WHICH DROPS A DEEP TROUGH INTO
THE GREAT BASIN THEN FORMS A CUTOFF LOW OVER CENTRAL CA. WILL
DISREGARD THIS IDEA SINCE IT IS NOT SUPPORTED BY ANY OF THE OTHER
MODELS. PREFER TO FOLLOW THE MORE PROGRESSIVE GFS SINCE IT HAS SHOWN
FAIRLY GOOD RUN TO RUN CONSISTENCY AS OF LATE. FOLLOWING THIS
IDEA... A DRY NORTHWEST UPPER FLOW PATTERN WILL PREVAIL OVER
CENTRAL CA. WITH A WARM AND DRY AIRMASS NOW ESTABLISHED OVER THE
AREA...WILL KEEP TEMPS SLIGHTLY ABOVE SEASONAL NORMALS FOR EARLY
MAY. EXPECT SOME CUMULUS BUILDUPS THROUGH THURSDAY OVER THE HIGH
SIERRA EACH AFTERNOON FROM MOISTURE POOLING...OTHERWISE SKIES WILL
BE MAINLY CLEAR THROUGH THE PERIOD.

&&

.AVIATION...AREAS OF MVFR CIGS DEVELOPING THROUGH 18Z TODAY ALONG
THE WEST SLOPES OF THE TEMBLOR AND DIABLO RANGE DUE TO MARINE LAYER
INTRUSION INTO COASTAL VALLEYS AS WELL AS OVER THE FOOTHILLS OF THE
SOUTHERN SIERRA NEVADA. LOCAL MVFR VISIBILITIES IN THE SAN JOAQUIN
VALLEY DUE TO MIST FROM 12Z THROUGH 15Z. OTHERWISE VFR CONDITIONS
PREVAILING 12Z SUNDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO
TAFS FOR KMCE...KFAT AND KBFL.

&&

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

&&

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

DUDLEY/DS

Event by event

1 debris flow. Local standard time, as filed.

Debris Flow, S Sierra Foothills

When
April 29, 6:00 AM PST to April 30, 11:59 PM PST
Where
S Sierra Foothills forecast zone
Reported by
PARK/FOREST SERVICE

After years of sporadic but small rock slides over Highway 140 going into Yosemite National Park through Mariposa (including a minor one on the 16th of this month), a major rock slide occurred about 6.2 miles WSW of El Portal on the 29th and closed the highway between Mariposa and the Park entrance.

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.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in California in 2006Every state in 2006This day in weather historyWarnings in California, April 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: 5509845.