If you spend much time in the mountains, sooner or later you're going to get caught in a severe thunderstorm. I don't mean you're going to hear a little thunder and get a little wet. I mean you're going to find yourself in the middle of a heart pounding, ear splitting, ozone smelling, sense numbing storm that drenches you through and through and wrings the nerves from your body.

Having been caught in such thunderstorms while climbing in Yosemite, running in the San Gabriels, and running at Mt. Pinos, I do my best to avoid the beasts. Sometimes, it is not an easy thing to do.

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

In normal to wet rain seasons vernal pools can be found throughout the Simi Hills. The pool pictured above is near the sheep corral at China Flat, and another small pond was found nearby, along Albertson Motorway fire road. I've also found vernal pools in the Rocky Peak area and near Sage Ranch.

Geologically, the Simi Hills are characterized by the sandstone rocks of the Chatsworth formation. These inclined layers are of varying hardness, and erode at different rates. It's my guess that water collects in sandy soils between, or at the base of, the more resistant layers.

The photographs of the ponds at China Flat are from Sunday's Scenic Route to Simi Peak run.

Lasky Mesa from a ridge near Bell Canyon. Low clouds from a rapidly advancing marine layer are moving into the San Fernando Valley. Saddle Peak can be seen in the distance, on the right.

From a run earlier earlier this week.

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.

Simi Valley, with the snowy mountains of Los Padres National Forest beyond.

From a run at Sage Ranch Park.

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.