Mountain Weather

Orographic lift, waves, and turbulence over the San Jacinto Mountain Range
Orographic lift, waves, and turbulence over the San Jacinto Mountain Range

After last Sunday’s record-setting storm in Southern California, and the cool, unsettled weather during the week, we expected snow conditions on Mt. San Jacinto to be even better than on previous trips this March. But snow conditions — especially backcountry snow conditions — aren’t always what you expect. The new snow, maybe a foot of it, was as thick as wet concrete. If we’d had a little kiwi fruit flavoring, it would have been perfect for shave ice.

A mountain wave cloud near Toro Peak
A mountain wave cloud near Toro Peak.

Even if the snow wasn’t what we had hoped for, the day was extraordinary. Another weak front was moving into Southern California and the strong onshore flow ahead of the front was creating several kinds of interesting mountain weather phenomena — some common and some not so common.

Riding up the tram, we could see plumes of dust blowing across the desert floor east of Banning Pass, and a stack of lenticular clouds hovered over the mountains east of San Gorgonio Mountain. It was breezy at the upper tram station, and from the walkway descending to Long Valley, we could see rimed trees on the southeast side of San Jacinto Peak.

Video of sheets and filaments of turbulence-induced cloud on San Jacinto Peak.
Video of sheets and filaments of turbulence-induced cloud.

We skied up a beautiful untracked drainage south of the Round Valley trail, and eventually worked our way over to Long Valley Creek and then to Tamarack Valley. We were almost to the top of the steep step above Tamarack Valley, and had paused for a moment to look around. There was a distinctive wave cloud to the southeast, and the lower cloud deck was beginning to engulf Toro Peak (8716′). I turned to continue up the slope, and as I looked up, the first of a series of tumbling and twining filaments of gossamer cloud swept past in the turbulent west-northwest flow (video).

Six months ago, also before the passage of a cold front, I’d seen similar clouds on Boney Mountain, in the Santa Monica Mountains. In that case and here on San Jacinto, a moist layer in a stably stratified westerly flow was being lifted over a mountain range. Depending on whether the flow remained laminar, or became transitional or turbulent; a wave cloud, transient wave cloud, or these turbulent thin sheets of cloud might form. In each case the atmosphere was becoming more moist and the clouds were precursors to the formation of a more widespread and persistent cloud layer.

Cygnus Loop Supernova Shockwave
Cygnus Loop Supernova Shockwave

These vaporous, turbulence-induced clouds bear a striking resemblance to interstellar molecular clouds. Both appear to occur in a high-Reynolds-number regime, and each appears to consist of a cohesive, thin sheet of condensate that can be stretched, sheared, undulated and torn. As in the case of its interstellar counterpart, when viewed edgewise, the clouds look like they are comprised of thin, web-like filaments.

The title photo was taken a little below the summit, after ascending the peak. It’s a view to the south, past Jean Peak (10,670′) and Marion Mountain (10,362′), and shows the terrain induced uplift, waves, and turbulence over the San Jacinto mountain range. The flow is from the right to left.

Most Rain in Los Angeles During a La Nina in the Last 60 Years

Between storms at Ahmanson Ranch

It has been a remarkable rain season in Southern California. December 2010 was the wettest December in Los Angeles in 121 years. Then Sunday, an exceptionally strong system produced record-setting rainfall in Los Angeles, Ventura, Santa Barbara, and San Luis Obispo counties with some locations recording as much as one-third of a year’s normal rainfall in 24 hours!

Runners in the Los Angeles Marathon had to contend with rain, wind and cool temperatures. Of 19,763 runners, more than 10,000 were on the course for longer than 5 hours. According to a report in the Los Angeles Times sports blog, The Fabulous Forum, thousands of runners were evaluated for hypothermia, but only 25 runners were hospitalized.

Sunday evening rain rates in excess of an inch an hour were recorded in several areas, and a flash flood was reported in Woodland Hills with “mud and debris flowing down the street” and “at least four to five vehicles stuck in flowing water.” Downtown Los Angeles (USC) recorded 2.42 inches of rain Sunday, breaking a record set in 1943. Santa Barbara Airport had its wettest day on record, recording 5.23 inches of rain. Here’s an archived copy of the NWS Record Report for March 20, listing some of the rainfall records for the day.

Some phenomenal rainfall amounts were recorded over the course of the storm. Van Nuys recorded 6.74 inches of rainfall, Northridge 6.08 inches, Newhall 7.20 inches, Camarillo 5.58 inches, Rose Valley 10.99 inches, Montecito Hills 7.70 inches, San Marcos Pass 10.72 inches, and Gibraltar Dam 11.73 inches. Here’s an archived copy of a NWS report with some rainfall and snowfall totals for the storm.

Downtown Los Angeles increased its water year rainfall total to 18.55 inches, or about 123% of normal. This makes the 2010-2011 water year the wettest in Los Angeles during a La Nina over the last 60 years, surpassing the totals recorded during the strong La Ninas of 1955-56 (99% of normal) and 1973-74 (106% of normal), and weak La Ninas of 1967-68 (110%) and 2000-01 (118%).

Update March 25, 2011. Since Tuesday, two more frontal systems have swept through Southern California,increasing the water year total at Downtown Los Angeles (USC) to 19.55 inches, or 129% of normal!

The title photograph is from a very wet and muddy run this afternoon through Upper Las Virgenes Canyon Open Space Preserve (Ahmanson Ranch), in eastern Ventura County.

Before the Deluge

View east from near the top of the Bulldog climb

Weather models were forecasting anywhere from 3.5 to 5.5 inches of rain at Van Nuys for the storm coming in tonight, so this afternoon seemed like a good time to get in a run.

I hadn’t run the Bulldog loop since the Bulldog 50K last August, and needed to catch up on trail conditions, what was blooming, and re-familiarize myself with the difficulties of the Bulldog Climb.

The short version is that the trail along Malibu Creek near the M*A*S*H site wasn’t flooded, but would be in the next 24 hours. Tree poppy, nightshade, hummingbird sage, woolly blue curls, ceanothus and paintbrush were blooming. And the Bulldog Climb was still hard.

It looked and felt like the day before a big storm. Temps were cool, and there was a thick deck of high clouds. Along the crest between the Castro “T” and the Malibu Bowl landslide the wind was blowing in strong gusts from the ESE, and it looked like the clouds might lower, thicken, and unleash a torrent at any time.

Near the end of the run, descending to Tapia Park, I was surprised to see my shadow and some blue sky. That didn’t last for long. By 7:00 the first drops of what would be a record-setting storm started to dot the driveway.

The title photo is a view east along Castro Crest and Mesa Peak Mtwy, and the route of the Bulldog Loop. Saddle Peak is in the distance. Here are a few additional photos. Click for a larger image and description:





Mesa Peak Mtwy




Woolly Bluecurls




Brents Mountain

Some related posts: Bulldog 50K 2010 Notes, Malibu Creek State Park Scenic Loop, Bulldog Loop and the Corral Fire

Southern Alligator Lizard

alligator lizard (Elgaria multicarinata)

An alligator lizard (Elgaria multicarinata) sunning itself on a grassland or chaparral trail isn’t about to move unless it positively, absolutely, for sure, without question has to.

I’ve encountered (and jumped over) a number of alligator lizards while running Southern California trails, and don’t recall one ever being in a hurry to move. It’s a case of fight or flight — or just sit there. Putting the camera a few inches from its nose resulted in only an almost imperceptible tilt of the head. I can never decide if they’re playing possum, or maybe trying to decide if I’m too big to eat. And they will bite.

Because of their small limbs and long body, at first glance they are sometimes mistaken for a snake. When they finally do decide to move, they do so  using a rapid lateral undulation of their body, with little apparent involvement of their limbs. Some research has concluded that this form of locomotion is more energetically efficient (Gans, 1975), while other research (Walton et al.,1990) suggests that limbed and limbless locomotion may have similar energetic costs.

The alligator lizard appears to be part way through a transition from a fully limbed lizard to a more snake-like body with reduced limbs. This change in form has occurred in a number of species, and in a paper published in 2006 (Wiens, Brandly & Reeder) the question was posed why this trait repeatedly evolves in lizards and snakes. They postulate that in addition to more traditional explanations, that biogeographic isolation and competition may play important roles.

For more info about the alligator lizard, see this San Diego Zoo fact sheet.

Back to San Jack

After skiing Mt. San Jacinto (10,834′) last week, Charles and I decided to take advantage of the good snow and ski the peak again today. Warming temperatures had thinned the snowpack a bit, particularly on the flats in Long Valley (8400′), but there was still plenty of snow.

The temperature was a little cooler than last week, particularly on the summit, where a brisk west wind increased the wind chill. I didn’t dig my better gloves out of the pack, and the light (knit) gloves I used for skiing up were like wearing no gloves at all. After spending fifteen cold minutes on the summit, I bailed to the south side of the peak, near the summit hut, and warmed up.

Once again, there was outstanding skiing on the sun-warmed slopes to the south and southeast of the summit. The surface of the snow had been transformed into a velvet-like layer of fine-grained corn snow. You couldn’t pick a bad line, and Charles and I would yell at each other, “you’ve got to see the snow over here!”

Conditions were more variable in the trees on the east-facing slopes above Tamarack Valley, but there were still some excellent sections out in the sun. Threading our way through the trees on the low angle slopes leading to the Round Valley Trail was fun, and in an peculiar way, so was skiing the well-traveled snowshoe track down the trail to Long Valley.

The title photo is of Long Valley Creek below Round Valley. As the snowpack melts, deep wells and moats typically form along streams. These can be anything from an inconvenience, to a life-threatening hazard that is impossible to cross. Snow bridges melt from below, as well as above, and are difficult to evaluate. It can be unnerving to cross a large Sierra creek on a snow bridge in the Spring, when no other option is available.

Here are a few additional photos. Click for a larger image and description:





Round Valley Trail




Bowl Below Miller Peak




Summit of Mt. San Jacinto

Good Snow, Great Weather on Mt. San Jacinto

Drainage below Tamarack Valley

If you were going to pick the most pleasant conditions possible to ski San Jacinto Peak (10,834′), today’s weather would be hard to top. The midday temperature on the summit of the peak was around 40-45 degrees. Winds were light, and it was pull-up-your-sleeves warm — but not broiling — most of the way up the peak.

There was still a lot of untracked snow from last week’s storm, and overall the snow conditions were very good, especially on the steeper, sun warmed slopes southeast of the summit, and in the trees lower on the peak. Here are a few additional photos. Click for a larger image and description:





Cornell Peak Above Tamarack Valley




East Ridge of Mt. San Jacinto




Below Summit of Mt. San Jacinto