Category Archives: weather|southern california

landscape, los angeles, nature, photography, weather, weather|southern california

Looking For Local Impacts of Tropical Storm Hilary

first published & last updated
Click on thumbnails for more info & larger image.
New grass in Upper Las Virgenes Canyon Open Space Preserve (Ahmanson Ranch), 10 days after the passage of Tropical Storm Hilary
Rare Summer grass at Ahmanson Ranch as a result of Hilary’s rain.

Update September 14, 2023. Mustard is sprouting along Ahmanson’s fire roads, and more surprising — a few mushrooms.

Update September 8, 2023. The new grass from T.S. Hilary’s rain is coming in nicely at Upper Las Virgenes Canyon Open Space Preserve (Ahmanson Ranch).

Tropical storms are a different kind of weather beast than usually seen in Southern California. The warmer air associated with such storms can carry much more water and produce unusually high amounts of precipitation.

The first hints of Hilary approaching Los Angeles
The first hints of Hilary approaching Los Angeles.

The rain resulting from Tropical Storm Hilary shattered many daily and monthly records. Over decades of record keeping, most stations in the greater Los Angeles area had previously measured only a trace of rain on August 20 or 21, or at best, a few hundredths of an inch. Some stations had never recorded any rain on these days.

This Google Earth image with precipitation data from the California-Nevada River Forecast Center (CNRFC) shows the remarkable rainfall totals across Southern California for the 24-hour period ending at 5:00 a.m. on Monday, August 21, 2023.

A little mud in Las Virgenes Canyon after Tropical Storm Hilary. August 22, 2023.
A little mud in Las Virgenes Canyon.

The highest rainfall amounts occurred where the precipitation was enhanced by mountainous terrain. The northeast-facing slopes of the eastern San Gabriel Mountains, near Wrightwood, were ideally positioned in Hilary’s circulation to enhance rainfall. The Big Pine RAWS recorded over 6 inches of rain for the storm, Lewis Ranch slightly over 7 inches, and Lytle Creek nearly 10 inches.

Detailed observation and impact reports for Hilary are available from NWS Los Angeles/Oxnard, NWS San Diego and the Center for Western Weather and Water Extremes.

Crossing of Las Virgenes Creek, south of the pipeline station, on August 22, 2023, following Tropical Storm Hilary.
This crossing of Las Virgenes Creek was about the same as before Hilary.

Curious to see some of the local impacts of the storm, I ran at Ahmanson Ranch on August 22 and then a few days later at Malibu Creek State Park.

My West Hills weather station, about three miles from Ahmanson Ranch’s Victory Trailhead, recorded 3.86 inches of rain for the storm. After an initial technical hiccup, the Cheeseboro RAWS, overlooking Las Virgenes Canyon, recorded 3.52 inches of rain. This and other data suggest rainfall amounts in the Ahmanson area of at least 3.5 – 4.5 inches.

My Ahmanson run started at the Victory trailhead, went out East Las Virgenes Canyon, through part of Las Virgenes Canyon, and then up to Lasky Mesa. With that much rain, I was sure I would be wallowing in the mud and wading the creek crossings. But my shoes didn’t even get muddy!

Dry streambed of Las Virgenes Creek, north of the Las Virgenes Trailhead, on August 22, 2023, after Tropical Storm Hilary
Dry streambed of Las Virgenes Creek, north of the Las Virgenes Trailhead

There was certainly some mud, puddles, and a little erosion, but the impact of Hilary on Ahmanson was surprisingly minor. The ground must have been desiccated because Las Virgenes Creek had almost no increase in flow. The creek crossings near the pipeline station and south of the station were essentially the same as before Hilary. Even more surprising, there was no water at the crossing a little north of the Las Virgenes Trailhead.

As Hilary moved northward in California, the counterclockwise circulation of the storm increased the rainfall in the Santa Monica Mountains. Automated RAWS stations in Topanga, the Malibu Hills, and in Malibu Canyon recorded 4.0 to 4.5 inches of rain during the storm. CNRFC gridded precipitation data indicated higher amounts in some parts of the range.

Las Virgenes Creek, about 5 miles downstream of Ahmanson Ranch, in Malibu Creek State Park, a few days after the passage of Tropical Storm Hilary.
Las Virgenes Creek in Malibu Creek State Park, about 5 miles downstream of Ahmanson Ranch.

On August 27, I ran the Bulldog Loop in Malibu Creek State Park. The run started at a small parking area at the junction of Malibu Canyon & Piuma Roads. As I was running up the Tapia Spur Trail, I wondered if State Parks had — as a precaution — removed the seasonal bridge across Malibu Creek on the Crags Road Trail. On August 19, the day before Hilary drenched the area, the bridge had been in place for the Bulldog Ultra. If it wasn’t removed, did Malibu Creek get high enough to damage it?

Once again, I need not have worried. The bridge was just fine, and the reeds in the water near the bridge suggested only a modest increase in streamflow.

Slopes along Bulldog fire road following Tropical Storm Hilary.
It’s unusual for the slopes along Bulldog fire road to be this green in Summer!

It looked like Malibu Creek State Park received more rain than Ahmanson Ranch. There was slightly more erosion on the dirt roads and some small sluffs/slides, including one tree that slid onto Mesa Peak Mtwy fire road. A tree had also fallen near the beginning of the Forest Trail.

Back at Ahmanson on August 31, things were drying out, but it was beginning to look like Spring. Grass was sprouting all over Ahmanson Ranch. It will be interesting to see if the grass survives the inevitable heat and grows enough to turn the hills green. The little bit of rain and cooler weather over Labor Day weekend will help. Some out-of-season wildflowers could also result from a false Spring.

Yesterday, I did a run in Topanga State Park, and the story was much the same. There was some minor erosion on the fire roads, but none of the larger sluffs and slides seen during the rainy season. There was no new damage to the Musch or Garapito Trails. It did look like the flow had increased on Garapito Creek with Hilary’s rain, and there was a still little water in the mainstem of the creek.

landscape, photography, running|adventures, san gabriel mountains, trails, trails|san gabriels, weather, weather|southern california, wildflowers

Dealing with the Heat on Strawberry Peak and San Gabriel Peak

first published & last updated
Click on thumbnails for more info & larger image.
Early morning view of Strawberry Peak from the Strawberry Trail, near Lawlor Saddle.
Strawberry Peak from the Strawberry Trail, near Lawlor Saddle.

Last weekend I’d considered doing a run from Red Box, but finally decided to go to higher elevation and do a combination run and climb.

Blazing star near the bottom of the Bill Riley/Mt. Disappointment Trail
Blazing star.

The puzzle to solve this weekend was to find a run that was closer to home, higher than the Santa Monica Mountains, and had a “decent amount” of elevation gain. The solution put me right back at Red Box, doing two of the most popular peaks in the Front Range — Strawberry Peak (6164′) and San Gabriel Peak (6161′).

I’d done these peaks as a duo several years ago. The basic details remain the same and are described in this post.

The main difference is that the 2018 run/hike was on a cool day in March, rather than a hot day in August. In 2018, I did San Gabriel Peak first, then Strawberry. The order didn’t matter. The temperature on both peaks that day was mostly in the 40s.

Mt. Disappointment (left) and Strawberry Peak from the San Gabriel Peak Trail.
Mt. Disappointment (left) and Strawberry Peak from the San Gabriel Peak Trail.

Today, it was essential to do Strawberry first, and get started early. The use trail between Lawlor Saddle and Strawberry’s summit faces south and east, and has very little shade. It’s steep and strenuous an no fun at all in the hot sun.

I left the Red Box parking lot at about 6:00 a.m. On the way up, the temperature ranged from the mid-50s to the mid-70s. On the way down, in some places it was already in the 90s. While it was hot in the sun on the upper part of the mountain on the descent, the traverse around Mt. Lawlor on the Strawberry Trail was still mostly in the shade and a relatively cool 75 to 80 degrees.

San Gabriel Peak isn’t the solar oven that Strawberry is. Much of the Bill Riley/Mt. Disappointment Trail faces north and a scrub oak forest provides some shade. Continuing up San Gabriel Peak after doing Strawberry, the temps were generally in the low to mid-80s.

Some related posts: Front Range Duo: San Gabriel Peak and Strawberry Peak, Blazing Star

ahmanson ranch, black & white, los angeles, nature, photography, quirky, running, southern california, trails, upper las virgenes canyon open space preserve, weather, weather, weather|southern california

Ahmanson Ranch Hot Seat

first published & last updated
Click on thumbnails for more info & larger image.

Ahmanson Ranch Hot Seat. Photography by Gary Valle'.

It was a little past 3:00 in the afternoon when I passed this straight-backed wooden chair along an Ahmanson Ranch trail. The Tempe thermometer clipped to my pack read over 100 degrees.

It gets REALLY hot at Ahmanson Ranch (Upper Las Virgenes Canyon Open Space Preserve). In the direct sun the temperature can be 10°F-15°F hotter than in the shade, and there is very little shade at Ahmanson. In-the-sun temperatures of 100°F or more are common in the Summer but can occur just about any time of the year.

There are two weather stations I use to get an idea of the weather conditions at Ahmanson Ranch — the Cheeseboro RAWS and Valley Circle Estates Weather Underground station. Weather station thermometers are usually shielded from the direct sun by a white, ventilated enclosure. The Cheeseboro RAWS includes a measurement of the “Fuel Temperature.” This is generally a better indication of the temperature experienced by a runner, hiker, or rider in the direct sun.

Update on July 29, 2023. Rounding the temperature to whole degrees, my West Hills weather station recorded a high of 100°F, or higher, for 15 consecutive days this July (7/13/23 to 7/27/23). The station is about three miles from the Victory Trailhead at Ahmanson Ranch.

Some related posts: Some Summers Are Hotter than Others, Run to the Cheeseboro Remote Automated Weather Station

adventures, landscape, los angeles, nature, nature|weather, photography, running, running|adventures, san gabriel mountains, snow, southern california, trails, trails|san gabriels, weather, weather, weather|southern california

It’s Mid-July And There Is Still Snow in Los Angeles County!

first published & last updated
Click on thumbnails for more info & larger image.
Snow in the lee of the West Ridge of Mt. Baden-Powell.
Snow in the lee of the West Ridge of Mt. Baden-Powell.

You might not see it from the Los Angeles side of the mountains, but there is still some snow on the higher, north-facing slopes of the San Gabriel Mountains.

During and after storms, snow-laden southerly winds dump their load on the backside of the crest, creating deep drifts, cornices, and compacted slabs of snow. This snow is often the last to melt, not only because it doesn’t face the sun, but because there is more of it.

Mt. Burnham, Peak 9086, and Mt. Baden-Powell from near Throop Peak.
Mt. Burnham, Peak 9086, and Mt. Baden-Powell from near Throop Peak.

This morning, I was doing an out-and-back from the Windy Gap Trailhead in the Crystal Lake Recreation Area to Mt. Baden-Powell. The Windy Gap Trail climbs 1730′ in 2.6 miles, joining the PCT at Windy Gap. From there the trail follows the spine of the San Gabriels past Mt. Hawkins, Throop Peak, and Mt. Burnham to Mt. Baden-Powell.

I usually do this run from Islip Saddle, but with Angeles Crest Highway (Highway 2) closed between Red Box and Vincent Gap, the Islip Saddle trailhead isn’t accessible.

Snow on the west ridge of Mt. Baden-Powell. July 9, 2023.
Snow at about 9100′ on the west side of Mt. Baden-Powell.

Whether you start at Crystal Lake or Islip Saddle, the length of the run is about the same — a bit over 16 miles. The main difference is that the Windy Gap Trailhead is about 800′ lower in elevation. On the plus side, the Windy Gap Trail is very scenic; on the minus side, it faces south and can bake in the midday sun.

On today’s run, I encountered the first snowbanks at an elevation of 8870′, near the Dawson Saddle Trail junction. Out of curiosity, I tried to follow the trail and soon realized that was a mistake. I was more or less forced to skirt the downhill side of a lengthy and deep drift — it being too steep and icy to cross directly.

Mt. Baldy from the summit of Mt. Baden-Powell. July 9, 2023.
Mt. Baldy from the summit of Mt. Baden-Powell. July 9, 2023.

For the remainder of the run, I switched to the early season tactic of staying on the crest when the trail deviated onto shaded, north-facing slopes. These areas might have significant snow on the trail. This only happens in a few places, such as when the PCT works around Mt. Burnham. There is a use trail that ascends the west ridge of Mt. Burnham, and then returns to the PCT.

The conditions today are reminiscent of those found here in early July 2005. July 3rd of that year there was still snow on the summit of Baden-Powell, and there was deeper snow in the areas where there was snow today. We had a lot of storms this rain season, but in Rain Year 2004-2005 Downtown Los Angeles (USC) recorded about 9 inches more rain than during the 2022-2023 rain year!

Here is a short slideshow of some photos taken on the run. I’ve also included a few photos from the run to Baden-Powell in 2005 for comparison.

ahmanson ranch, photography|landscape, photography|trail running, running, smmc open space, trails, upper las virgenes canyon open space preserve, weather|southern california

Lasky Mesa Runner, Grassland, and Clouds

first published & last updated
Click on thumbnails for more info & larger image.

Lasky Mesa Runner, Grassland, and Clouds

Brett was down for a few days, and as an initial run we did a loop from the Victory Trailhead of Ahmanson Ranch, through part of Las Virgenes Canyon, up onto Lasky Mesa, and then back to the trailhead.

Upper Las Virgenes Creek still flowed. Valley oaks were full with new leaves. The green grasses of the rain season had finally turned, and rare May cumulus clouds were painted on postcard skies.

It was an outstanding run!

ahmanson ranch, nature|trees, nature|weather, photography, smmc open space, trails, upper las virgenes canyon open space preserve, weather|southern california

Ahmanson Valley Oaks Finally Get Their Leaves

first published & last updated
Click on thumbnails for more info & larger image.

Cold weather delayed the leafing out of valley oaks at Ahmanson ranch until late March and early April 2023.

According to preliminary NWS reports, Downtown Los Angeles (USC) recorded average monthly temperatures well below normal in November 2022 and January thru March 2023. March was particularly cool, with an average high of about 64 degrees and an average low of about 50 degrees.

Besides high heating bills, Southern California’s unusually cold Winter affected several seasonal processes, one of which was when the valley oaks at Ahmanson budded and grew new leaves.

The leaves of valley oaks at Ahmanson Ranch typically turn in mid-December, and the trees usually begin to leaf out during the latter half of February. Depending on the tree’s microclimate, the emergence of new leaves may vary by a week or more.

Cooler than normal temperatures during January to March 2023 delayed the leafing out of these valley oaks in Las Virgenes Canyon.
Valley oaks in Las Virgenes Canyon in early April 2023.

The earliest I’ve photographed a valley oak at Ahmanson sprouting new leaves was February 3, 2015. Last year, a valley oak had new leaves on February 10, 2022.

The latest I’ve seen valley oaks sprouting new leaves is this year — from about March 20, 2023, in favored locations to April 4, 2023, in cooler areas such as Las Virgenes Canyon.

Prior to this year, the latest I’ve photographed a valley oak at Ahmanson with new leaves was March 9, 2009.

(Officially named Upper Las Virgenes Canyon Open Space Preserve, most users refer to the open space area as Ahmanson Ranch or simply Ahmanson.)

Some related posts: Revitalized Valley Oak at Ahmanson Ranch, Goldfields Are Blooming and Valley Oaks Greening, Valley Oak Leaf