It's been late February since Southern California has had a good soaking rain. As of May 1, the water year rainfall total for Downtown Los Angeles (USC) stands at 13.42 inches. This is 90% of the 1921-2006 average of 14.87 inches. According to the NWS 1921-2006 dataset, the average amount of precipitation in May and June is 0.3 inch and 0.1 inch, respectively. We'll see if we get that much this year!

La Niña appears to be winding down.  In it's April 30 ENSO Wrap-Up, the Australian Bureau of Meteorology characterizes Pacific climate patterns as being generally neutral, "with the majority of indicators returning to near-normal levels." The April 28 ENSO Update from the CPC suggests that La Niña will continue through May-July 2008, but many of the factors discussed indicate general weakening of La Niña. Based on the ONI and MEI, La Nina conditions have existed since about August of 2007.

The photograph of the sun-parched mustard leaf is from a run at Ahmanson Ranch on April 29, 2008.

Technorati Tags: la nina, Los Angeles weather

The beauty and intensity of the day was infectious. Hours before a cold low pressure trough digging down from the Pacific Northwest had carried showers, thunder, hail, and chilly temps into Southern California. Its rainfall had refreshed the greens of the hills, and accentuated the yellows, purples and reds of the wildflowers along the trail. Its blustery winds had cleansed the sky.

A few minutes before I had completed one run, and now was starting another. I wasn't certain how much farther I would run -- I just knew I had to run.

The day had begun with friends on the Secret Trail in Calabasas. We had run up and over the shoulder of Calabasas Peak, and then ascended Saddle Peak via the Stunt High Trail and Backbone Trail. The view from the summit of Saddle Peak had extended beyond Santa Monica Bay and Palos Verdes Peninsula to the South Bay and Saddleback Mountain. New snow glistened on Mt. Baldy, and to the west the rocky summits on Boney Mountain stood in bold relief.

That 14.5 mile run had ended at Tapia Park. Now I was on the Tapia Spur Trail on the first climb of the Bulldog Loop. On the wind sheltered slope the bright yellow blossoms of tree poppy had begun to unfurl, absorbing the warmth of the midday sun. Distant peaks loomed to within an arm's reach, and my legs seemed to draw energy directly from the trail. It was a long run kind of day.

Notes: The title photograph is of Saddle Peak from the Backbone Trail, in the Santa Monica Mountains, near Los Angeles. Mt. Baldy can be seen in the distance. The combined length of the runs was about 29 miles with an elevation gain of about 5000 ft.

Some related posts: Tapia Bound, Bulldog Loop and the Corral Fire, Fog Along Malibu Creek

This photograph of downtown Los Angeles and Century City was taken Sunday morning from the Backbone Trail in Topanga State Park while doing the Will Rogers - Temescal Loop from the "end of Reseda" in the San Fernando Valley.

At the time an offshore wind was scouring out low-lying fog trapped in the Los Angeles basin by a low altitude temperature inversion.

Related posts: California State Park Closures, Will Rogers - Temescal Loop

Southern California can have inclement Winter weather. This January downtown Los Angeles experienced a streak with 8 days of measurable rain, and last year temperatures in the suburbs plunged to a frigid 20°F. Maybe this doesn't compare to Seattle's 2005-2006 rain streak of 27 days, or International Falls' recent record low of 40° below zero, but it qualifies as rainy and cold none the less.

Today it was not rainy and cold. It was just about as pleasant as a day could be. Skies were blue, winds were light, and the temperature was in the mid-seventies. Starting at the Wendy Dr. trailhead on Potrero Rd., we enjoyed the perfect weather by doing a 14.5 mile variant of the Boney Mountain Half Marathon Course.

The photograph above is of the Hidden Pond Trail near Hidden Pond -- recently restored by Winter rains.

Related posts: Boney Mountain Half Marathon, Big Sycamore Canyon Circuit, Boney Mountain - Big Sycamore Canyon Circuit

It's about time -- all the rain in Southern California is finally turning our hills green! Last year the hills of East Las Virgenes Canyon were sun bleached and rain starved.

According to preliminary NWS data, Downtown Los Angeles (USC) recorded measurable rain on each day from January 21 to January 28, 2008. Based on this NWS ranking for 1921-2006, this puts this eight day period in the top six of the station's wettest streaks from 1921-2007.

So far this water year Downtown Los Angeles has recorded 11.73 inches of rain, which is 4.77 inches above normal. Last year on this date Los Angeles had recorded only 1.5 inches of rain. Even if Los Angeles were to receive no rain through the entire month of February (not likely), we would still go into the month of March ahead of normal.

The photograph is from a muddy run at Ahmanson Ranch -- now Upper Las Virgenes Canyon Open Space Preserve.

Ran Rocky Peak road both days last weekend. Saturday's outing was a 7.3 mile rainy day run out to the Chumash Trail junction and back. Sunday's was a little longer, about 9.3 miles -- past the Chumash Trail junction to the highpoint on the road sometimes referred to as "the fossils."

The photograph of Simi Valley was taken on Sunday afternoon, just after turning around to head back. The wind was blowing in fitful gusts, and a gray wall of rain loomed to the west. It wasn't raining yet, but the trailhead at Santa Susana Pass was about 50 minutes away, and there was a feeling things were going to get very wet, very soon.

Over the weekend the west coast was slammed by a series of storms that increased the water year rainfall total at Downtown Los Angeles to an inch above normal and the Sierra snow pack from 60% of normal to over 100%.

So far this rain season, Southern California has dodged a La Nina bullet. This AHPS Precipitation Analysis for the water year indicates much of the area has received near normal to above normal precipitation.

Will Southern California rainfall remain near normal? The Climate Prediction Center's precipitation outlook for Jan-Feb-Mar (issued Dec. 20), the ERSL/PSD Nov-Mar La Nina precipitation composite, and most other longer range forecast tools say no.

On the other hand... the base state of the atmospheric circulation remains more or less what it has been the past several months, so it doesn't seem unreasonable to suggest that our pattern of near normal rainfall might continue.

The current NWS 6-10 day and 8-14 day precipitation outlooks project below normal for Southern California, but there are some hints that a system with a lower latitude track could affect the area near the end of the 14 day period. We'll see!

Note: The ESRL/PSD Composite ENSO plots page was updated yesterday to correct an issue that resulted in the wrong set of years being used for its Winter La Nina composites. As a result the La Nina composite precipitation map in this post is drier in coastal Southern California than in the map originally published in the post Southern California 2007-2008 Winter Precipitation Outlook.

Wow, it was windy! I was on an exposed ridge between Tri-Peaks and Big Dome, getting pushed around by a unrelenting offshore wind, trying to keep my footing, and take a few photos. About the time I was traversing the ridge, Laguna Peak -- the peak in the photograph with all the communications equipment on its summit-- recorded a gust of 67 mph.

But this is a mere breeze by Laguna Peak standards. A communication facility operated by the U.S. Navy, the weather station has recorded hurricane force winds on numerous occasions. Several of the wind events listed in the NWS document A History of Significant Weather Events in Southern California reference Laguna Peak. In March of 1991 a gust of 125 mph was recorded at the peak.

Update 12/25/07. Merry Christmas! This morning, about 6:15, Laguna Peak recorded a wind gust of 91.8 mph and several gusts in excess of 85 mph. Between 10:00 a.m. and 11:30 a.m. several gusts over 90 mph were recorded, including one measured at 91.9 mph.

La Jolla Valley is the small valley just below Laguna Peak. Isolated and scenic, it is a "must do" hike or run that can be accessed from the Ray Miller trailhead on PCH, or from Big Sycamore Canyon.

The peak on the left in this wider 16:9 format view is Mugu Peak. Its summit overlooks Pt. Mugu and is a relatively short side trip from the Mugu Trail.

Offshore, two of the Channel Islands can be seen -- Anacapa (left) and Santa Cruz.

When I see crystals of hoar frost sparkle in the Winter sun it triggers a child-like awe. On Sunday's Condor Peak Trail Run, several sections of trail glittered as we ran into a low morning sun. On the cold east face of Fox Mountain, a fine, needle-like frost coated the edges and surfaces of leaves and twigs that had collected in pockets on the steep slope.

Digitally magnifying a small section of a 10 Mp image revealed that the frost is comprised of  hollow columns, and further magnification shows that the columns are hexagonal, with lengthwise facets.

Racing the sun,
Waiting for rain,
Listening to a meadowlark sing.

From a run at Ahmanson Ranch -- now Upper Las Virgenes Canyon Open Space Preserve. Here's a larger view of the full 16:9 frame.

For an update on this Winter's austere outlook for rain, see my November 29 Weathernotes.

Updated January 10, 2008. The ESRL-PSD Composite ENSO plots page was updated today to correct an issue that resulted in the wrong set of years being used for its Winter La Nina composites. As a result the La Nina composite precipitation map in this post has been updated.

Grasses sprouting as a result of our record setting September rainstorm have brushed our sun parched hills, fields, and woodlands with pleasing hints of green. Whether these areas will remain green depends on how much rain we receive this Fall and Winter.

According to the Climate Prediction Center's Weekly ENSO Update, issued October 1, La Niña conditions are present across the tropical Pacific and are likely to persist through early 2008. As a result, several longer range U.S. precipitation outlooks are similar to this Nov-Dec-Jan Precipitation Outlook, issued September 20 by the CPC.

The precipitation pattern projected for the western U.S. is typical of a La Niña, with an increased chance of higher than normal precipitation in the Pacific northwest and an increased chance of lower than normal precipitation in the southwest.

The September 20 CPC outlook indicates an "equal chance" of below normal, near normal, or above normal precipitation in the Los Angeles area. However, the La Niña has strengthened recently, so the next precipitation outlook may reflect a more pessimistic projection of Los Angeles area rainfall.

As mentioned above, the ESRL-PSD Composite ENSO plots page was updated today to correct an issue that resulted in the wrong set of years being used for its Winter La Nina composites. This updated precipitation map shows the mean Nov-Mar precipitation for the U.S. during 9 La Niña events from 1948 to the present. Note that the average La Niña rainfall indicated for coastal Southern California is in the 7.0-10.5 inch range, rather than the  10-15 inch range previously indicated in the ESRL-PSD graphic.

The two driest water years recorded in Los Angeles since 1877 have occurred in the last seven years. During the most recent, from Jul 2006 to June 2007, downtown Los Angeles (USC) measured only 3.21 inches of rain. In that context 10-15 inches sounds quite wet! We'll see.

The photograph of new grass sprouting amid oaks is from a run at Sage Ranch on October 1, 2007.

Los Angeles sometimes gets rain in September, but usually it is the result of tropical moisture from a dissipating hurricane, or perhaps the passage of the tail end of a weakening front. It is rare to see a low as cold, deep and energetic as the upper level low that deluged many areas of Los Angeles county Friday afternoon into Saturday.

Thunderstorms raked the San Fernando Valley Friday night, and several locations in and around the Valley recorded more than an inch of rain over the course of the storm. Los Angeles set a new rainfall record on Saturday, recording 0.40 inch of rain, and rainfall records were broken across the area.

In Southern California the first rain of the season often doesn't occur until October or November and is always savored. Especially this year, when Los Angeles has recorded only 3.21 inches of rain in the last 15 or 16 months, and a developing La Nina threatens to put the kibosh on Winter rain.

I celebrated the rain by doing an out and back run to "Fossil Point" on Rocky Peak fire road. Based on the size of the mud puddles on the dirt road, this unseasonable storm appeared to be wetter than any in last year's record dry rain season. Here's a panorama of the view northwest from the fire road to Oak Ridge, the Santa Susana Mountains and beyond.

Some related posts: San Fernando Valley from Rocky Peak, Rainy Morning on Rocky Peak Road.

With little new growth this Spring and Summer, coyote paths at Ahmanson Ranch have become so well worn that several have recently been posted with "Restoration Area - Please Keep Out" signs. Whether the canny coyotes will choose to cooperate remains to be seen.

Note: Ahmanson Ranch was acquired as open space in part to protect several sensitive species and their habitats. Some (human) use trails have evolved and "Restoration Area - Please Keep Out" signs are a reminder that the area is a preserve.

From a recent run at Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch).

Related post: Trickster