Long Shadows, Cool Canyons

first published December 10, 2010 & last updated June 22, 2023 Gary Valle

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Valley oak

It’s that time of year. Willows and wild walnut trees are showing some Fall color, and the valley oaks are losing their leaves. Even on a warm day, the long shadows, clear skies and low humidity of late Autumn cool the hillsides, generating chilled katabatic flows down gullies and canyons.

As temperatures warmed up this week I took a probe thermometer on my afternoon trail runs at Ahmanson Ranch (Upper Las Virgenes Canyon Open Space Preserve) and measured the temperature of some of these invisible streams.

My general weather data reference for the area is the Cheeseboro Remote Automated Weather Station (RAWS). The high temperature at the Cheeseboro RAWS ranged from 73°F on Tuesday to 75°F Thursday. The temperature in the shade at the Victory trailhead parking lot at the beginning of my runs (around 4:00-4:15) was about 70°F.

Tuesday, the temperature on the road about 1.1 miles from the parking lot, and above East Las Virgenes Canyon was about 69°F. A quarter-mile away, down in the dry streambed, the temperature was a chilly 47°F — a drop of 22°F.

Wednesday, I ran to upper Las Virgenes Canyon. The temperature at a saddle above the canyon was 66°F. Down in the canyon near one of the stream crossings, the temperature was 45°F — a difference of 21°F.

Thursday I ran back to the same point in Las Virgenes Canyon. Even though the high temperature for the day was about the same as Wednesday, the humidity was higher, and there were some high clouds. The katabatic flow was not as well-defined, and the temperature drop was only about 13°F.

Conditions during the week were not especially favorable for hillside radiational cooling, and I expect temperature differences of 30°F might be possible in ideal circumstances. In any case it feels like that in running shorts and a short-sleeve shirt.

nature, nature|environment, photography, photography|wildflowers, weather, weather|southern california

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Early Bloomers

published December 6, 2010 Gary Valle

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Wishbone bush (Mirabilis californica)

This autumn, the first measurable rainfall at Downtown Los Angeles was on October 4, 2010. Since then we’ve seen some rain in Southern California every 7 to 10 days or so. The storms haven’t been huge, but many locations have recorded near to above average rainfall for the water year to date. Some, like Santa Barbara and San Diego, are well above normal for the date.

Because of our erratic weather, many Southern California plants are opportunistic and will shift their growing and flowering season to take advantage of wet weather.

Discounting plants that normally bloom in autumn, one of the earliest of the early bloomers this autumn was this bigpod ceanothus in Pt. Mugu State Park, photographed on November 14. Another early bloomer was Wishbone Bush which was beginning to bloom in the Simi Hills on November 21. This Shooting Star was photographed at Sage Ranch on November 30. In the past couple of weeks I’ve also seen Prickly Phlox, Bush Monkeyflower and Wild Cucumber in bloom.

The title photograph is Wishbone Bush on the northeast ridge of Ladyface last week.

photography, running, trails, trails|smmc open space

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Cranking Up Las Llajas

first published December 5, 2010 & last updated March 6, 2024 Gary Valle

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Connector from Las Llajas Canyon to Rocky Peak Rd.

Ran a variation of the Chumash-Las Llajas loop this morning. One of the reasons for the run was to check out one of the larger vernal ponds in the Rocky Peak area and see if it had water. It didn’t.

Another reason is the loop is part of the grueling Bandit 30K/50K course, and the February 20th race date will be here before we know it.

The hill the MTBers are cranking up covers about miles 12 to 13 on the Bandit 30K course, and follows a gradual — but long — uphill in Las Lajas Canyon that gains 600′ of elevation over 3 miles. It’s just one of the fun parts of a tough 30K course, and 50Kers get to do it twice!