Why are the trails in such bad shape? December report from NWS. (24" of rain ...)

Statement as of 6:00 am PST on January 3, 2011​

... December 2010 was one of the wettest decembers ever recorded
across southwestern California... ​

Thanks in large part to a huge upper level low pressure system that
brought rain to the region from the 17th through the 22nd... December
2010 will go down in the record books as one of the wettest... and in
many cases the wettest... decembers in history across southwestern
California. Most areas across southwestern California received
between 3 and 6 times the normal rainfall for the month... or
300 to 600 percent of normal. ​

In downtown Los Angeles... the 10.23 inches of rainfall received in
December was the second most in any December since records began in
1877. It also made December 2010 the 14th wettest of any month in
history at the site... out of a total of 1602 months of record.
However... to be fair... only 5 months of the year... November through
March... could ever really compete for that record. Rainfall
in December 2010 was equal to nearly 70% (67.5%) of the entire
seasonal normal for downtown Los Angeles... which is 15.14 inches. ​

The following are rainfall totals for selected stations for December
2010 (in inches)... normal rainfall for the month of December...
percent of normal rainfall... the wettest previous December... and
where December 2010 ranked at that station in terms of rainfall.​

Dec 2010 Dec percent wettest Dec 2010
rain normal of norm Dec ranking
-------- ------ ------- ------- -------​

Downtown Los Angeles... .. 10.23 1.91 536% 15.80/1889 2nd
Los Angeles Airport... ... 8.83 1.79 493% 6.49/2004 1st
Long Beach Airport... ... . 10.41 1.76 591% 5.29/1971 1st
Burbank Airport... ... ... . 8.36 2.15 389% 8.07/1940 1st
Woodland Hills... ... ... .. 6.37 2.38 268% 8.44/2004 5th
Lancaster Airport... ... .. 3.96 1.01 392% 5.35/1984 3rd
Sandberg... ... ... ... ... .. 4.83 2.17 223% 10.26/1971 8th
Camarillo Airport... ... .. 7.21 2.11 342% 5.32/1964 1st
Oxnard (nws)... ... ... ... . 9.16 2.11 434% 6.25/1997 1st
Santa Barbara Airport... . 10.36 2.26 458% 6.78/1945 1st
Santa Maria Airport... ... 9.82 1.84 534% 7.50/1941 1st​

Rainfall for the month of November was generally 300 to 600 percent
of normal across the forecast area. ​

Average temperatures for the month were generally within two degrees
of normal... except 2 to 5 degrees above normal in the mountains...
Antelope Valley and the interior valleys. In general... maximum
temperatures averaged 2 to 4 degrees below normal in coastal and
valley areas... and near normal in the mountains and deserts. Low
temperatures averaged 3 to 6 degrees above normal... except up to 8
degrees above normal in the deserts... and generally 1 to 3 degrees
above normal across the Los Angeles and Ventura County coastal
plain. ​

The first few days in December 2010 were generally mild and dry
across the region. A storm system moved into central California on
the 5th. Its associated front brought rain to the region on the 5th
into the early morning hours of the 6th. Rainfall totals generally
averaged one third of an inch to three quarters of an inch across
the region. Gusty south winds affected the mountains... with wind
gusts of 40 to 50 mph common from the afternoon of the 5th through
the early morning hours on the 6th.​

Dry weather returned on the 6th and continued through the middle of
the month. A round of gusty northwest to north winds affected the
mountains and valleys of Los Angeles County and the Santa Ynez range
in Santa Barbara County late on the 10th into the 11th. Peak wind
gusts included 78 mph at Whitaker Peak... 62 mph at Camp Nine... 55
mph at Malibu Hills... 54 mph at Warm Springs... 52 mph at chilao and
at Montecito hills... 48 mph at Newhall Pass... 44 mph at Sandberg and
Saugus and 32 mph at Van Nuys. ​

The low level flow turned northeasterly on the 11th and 12th... and
an upper ridge of high pressure moved into the West Coast. This
brought well above normal temperatures to much of the region from
the 11th through the 13th. On the 12th... many new daily high
temperature records were set... including 89 degrees at San
Gabriel... 88 degrees in Camarillo... 87 degrees at Long Beach Airport
and ucla... 85 degrees at Burbank Airport... 84 degrees at the
National Weather Service in Oxnard... and 83 degrees at Los Angeles
Airport.​

A weak frontal system moved through the region on the 15th and
early on the 16th... bringing very light rainfall to the
region... generally on the order of one tenth of an inch or less. ​

A dramatic change in the weather pattern began after the 16th. A
large upper level low pressure system moved into the northeastern
Pacific... well off the coast of the Pacific northwest on the
17th... then lingered there through the 21st. The circulation around
the southern side of this upper low pushed very moist air with a
subtropical connection into the region. This ribbon of moisture
remained focused across Southern California from the 17th through
the 21st... bringing almost continuous rain to the region during that
time. Several impulses rippling through the moist subtropical flow
caused periods of heavy rain at times. On the 21st... the upper
low began to shift eastward... and its strong frontal system moved
across southwestern California late on the 21st and on the
22nd... putting an exclamation point on what was a very wet week. ​

Many daily rainfall records were set across the region from the 17th
through the 22nd. That storm system contributed greatly to making
December 2010 one of the wettest in recorded history across much of
Southern California.​

On the 17th... rainfall of 0.98 inches at Long Beach Airport set a
new rainfall record for the day. ​

On the 18th... daily rainfall records included 3.19 inches at Santa
Maria Airport and 2.80 at Santa Barbara Airport... both of which also
set new records for any day during any month of December. ​

On the 19th... daily rainfall records included 2.80 inches at
downtown Los Angeles... which was its 8th wettest December day
ever. At Santa Barbara Airport... the total of 2.79 inches set a new
daily record. It was also its 2nd wettest December day ever... the
wettest having been set the previous day. The daily total of 2.07
inches at Long Beach Airport set a new record for the day... and was
its 3rd wettest December day ever. At Los Angeles Airport... the
daily total of 2.23 inches set a new daily record... and was the 4th
wettest December day ever. A record daily rainfall of 2.13 inches
was also set at Santa Maria Airport on the 19th.​

Nearly 4 inches of rain fell near Oceano Airport in San Luis Obispo
County in a 24 hour period ending on the 19th. Several cars got
stranded in high flood waters... prompting evacuations.​

Strong south winds affected much of the region on the 19th...
with peak wind gusts including 72 mph at Mill Creek... 65 mph at
Lake Palmdale... 60 mph at Camp Nine... 58 mph at Grass Valley and
Pine Mountain... and 55 mph at chilao... .39 mph at Newhall Pass and
Saugus and 37 mph at Santa Maria. ​

On the 20th... new daily rainfall records were set at Long Beach
Airport with 2.03 inches... its 4th wettest December day ever... at
Santa Maria Airport with 1.44 inches... and at Los Angeles Airport
with 1.17 inches. Strong south winds affected the mountains again on
the 20th... with peak wind gusts including 74 mph at chilao...
66 mph at Mill Creek... 53 mph at Clear Creek and 46 mph at Camp
Nine. ​

On the 21st... a daily rainfall record of 1.21 inches was set at Long
Beach Airport. ​

On the 22nd... a daily rainfall record was set at Long Beach Airport
with 1.53 inches... and the daily record of 0.72 inches was tied at
Santa Maria Airport. ​

The week long siege of rain brought periods of flooding to the
region... along with some mud and debris flows and rock slides... the
most serious of which occurred on the 22nd. Significant flooding of
the transition Road between Interstate 10 and Highway 57 was reported
during the early morning of the 22nd... with a large amount of water
in lanes... and mud coming down from the hill sides. A small mountain
side collapsed onto Little Tujunga Canyon Road at Sand Canyon
Highway during the late morning hours... and rocks and debris covered
all lanes at one point. During the afternoon hours of the 22nd... all
lanes of Big Rock Creek Road in the Antelope Valley were covered by
flooding and debris... and mud and heavy flooding was reported on an
onramp to the 10 freeway east of downtown Los Angeles. Three cars
were trapped in flood waters on Avenue h east of Lancaster during
the early afternoon hours... and five people had to be rescued. A
funnel cloud was reported near the San Pedro area at 240 PM on the
22nd. ​

Rainfall totals for the week long storm were impressive... averaging
5 to 10 inches in coastal and valley areas... and 10 to 18 inches in
the foothills and mountains... with local totals as high as 24 inches
in the San Gabriel Mountains and the mountains of western Ventura
County.​

Some specific totals included 24.70 inches at Tanbark in the Los
Angeles County mountains... 24.09 inches at North Fork Matilija in
the Ventura County mountains... 18.90 inches at Crystal Lake... 18.66
inches at Nordhoff Ridge... 18.27 inches at Matilija canyon... 18.11
inches at San Gabriel dam... 17.72 inches at el Deseo ranch in the
Santa Ynez Mountains... 17.48 at West Fork heliport near Mount
Wilson... 17.10 inches at Tecolote Canyon in the Santa Ynez
range... 15.12 inches at San Marcos Pass... 13.50 inches at Rocky
Butte... 13.14 inches in Claremont... 12.72 inches in Pasadena... 12.26
inches at Lake Casitas... 9.56 inches at San Luis Obispo Airport...
8.87 inches in Ojai... 8.61 inches in Beverly Hills... 8.53 inches at
Long Beach Airport... 8.16 inches in downtown Los Angeles... 7.71
inches at Santa Maria Airport... 7.44 inches in Newhall... 6.93 inches
at the National Weather Service in Oxnard... 6.89 inches in
Northridge... 6.46 inches in Ventura... 6.18 inches in Thousand
Oaks... 6.10 inches in Agoura Hills... 4.92 inches in Woodland
Hills... 3.76 inches at New Cuyama and 3.47 inches at Lancaster
Airport.​

After a couple of dry days... another front swept through the region
late on the 25th and into the 26th. South winds ahead of the front
peaked at 46 mph at Vandenberg and 35 mph at Santa Maria.​

The front brought rainfall totals of one half inch to one inch in
most areas... with locally higher totals... especially in the foothills.
Some rainfall totals included 1.39 inches at lake Lopez... 1.38
inches at Oceano... 1.22 inches at Rocky Butte... 1.16 inches at San
Luis Obispo Airport... 1.05 inches at Santa Barbara Airport... 1.04
inches at Tanbark... 1.01 inches at Las Tablas... 0.90 inches at
downtown Los Angeles... 0.89 inches at Pasadena... 0.84 inches at
Santa Monica Airport and in Beverly Hills... 0.78 inches at the
National Weather Service in Oxnard... 0.72 inches at Long Beach
Airport... 0.67 inches at Burbank Airport and in Northridge... and
0.63 inches in Agoura Hills.​

In the mountains above 6000 feet... snow accumulations of 4 to 8
inches were reported... with 7 inches at mountain high ski resort
and 6 inches at Pine Mountain Club. ​

Behind the front... gusty northwest to north winds developed during
the evening of the 26th. Peak wind gusts included 70 mph at Whitaker
Peak... 54 mph at Malibu Hills and Camp Nine... 53 mph at Montecito
hills... 49 mph at Malibu Hills and 48 mph at Camp Nine. ​

The final system of the month swept through the region late on the
28th and 29th. Rainfall for this system ranged from 0.75 inches to
1.50 inches north of Point Conception... and between 0.50 and 1.00
inches south of Point Conception... with locally higher amounts in the
foothills. Some totals included 1.54 inches at San Luis Harbor...
1.50 inches at Rocky Butte and Cambria... 1.37 inches at
Lompoc... 1.22 inches at San Luis Obispo Airport... 0.92 inches at
Santa Maria Airport... 0.92 at Whittier... 0.91 at Claremont and
Tanbark... 0.82 inches at downtown Los Angeles... 0.78 inches at Long
Beach Airport and at the National Weather Service in Oxnard... 0.72
inches at Santa Barbara Airport... and 0.55 inches at Woodland Hills.​

Behind this front... widespread strong west to northwest winds
developed across the region during the afternoon of the 29th. Peak
wind gusts immediately behind the cold front during the afternoon
and early evening hours of the 29th included 64 mph at Laguna
Peak... 46 mph at Vandenberg hills... 44 mph at Santa Maria and
Gaviota... 40 mph at Oxnard Airport... Camarillo Airport... Morro Bay
and Ventura Harbor and 38 mph at Lompoc Airport.​

The winds shifted to a more northerly direction during the evening
hours... and the winds increased to damaging levels in some
areas... particularly across the mountains and valleys of Los Angeles
County and the Santa Ynez range and adjacent South Coast of Santa
Barbara County. Peak wind gusts during the evening of the 29th
through the morning of the 30th included 94 mph at Whitaker
Peak... 81 mph at Warm Springs... 72 mph at chilao... 71 mph at Camp
Nine... 67 mph at Sandberg... 61 mph at San Rafael Hills and
Saugus... 59 mph at Elizabeth Lake... 56 mph at Lancaster and Poppy
Park... 55 mph at Malibu Hills... 54 mph at Van Nuys Airport... 53 mph
at Montecito hills... and 42 mph at Burbank Airport. There were
reports of numerous trees down across the region with scattered
power outages. Exacerbating the problem was that the wet
soil... softened by all the rain... made it easier for trees to be
uprooted by the gusty winds. ​

 

Awesome weather report.

Fritz Coleman and all you LA weather ladies better look out!

 

Sorry......didn't need the NWS to tell me that we got a ton of rain the last few weeks.....I work outdoors and was driving from OC to Downtown LA during that time. I was able to experience the massive amounts of rain.

 

Great report, the snow sking has been Awesome. Happy Newyear.