A very wet East Las Virgenes Canyon and Trail on February 8, 2024, following seven days of rain. This was by far the wettest start to February in Los Angeles since recordkeeping began in July 1877.
Related post: Ahmanson Ranch and Upper Las Virgenes Creek After Six Days of Rain
After January 2023’s torrential rains and Hurricane/Tropical Storm Hilary’s drenching in August, here we are again, experiencing record rainfall.
Over the first six days of February 2024, Downtown Los Angeles recorded 10.2 inches of rain. That’s almost three-quarters of L.A.’s normal ANNUAL rainfall in just a few days and the wettest start to February on record! Some stations in the Santa Monica and San Gabriel Mountains recorded even more — over 13 inches in some locations!
How much did it rain at Ahmanson Ranch (Upper Las Virgenes Canyon Open Space Preserve)? Unfortunately the Remote Automated Weather Station (RAWS) on a hill between Upper Las Virgenes Canyon and Cheeseboro Canyon hasn’t been accurately measuring precipitation. A citizen weather station (KCAWOODL130) near the Victory Trailhead at Ahmanson Ranch recorded over 11 inches from February 1 – 6. Another station near Cheeseboro Road in Agoura (KCAAGOUR41) recorded over 9 inches.
Whatever the amount, it was a lot. Here is a short video, from a run at Ahmanson Ranch on February 7, 2024, to check out the conditions and creeks.
As I write this, more wet weather is forecast to affect the Los Angeles area, beginning sometime over the weekend of February 17-18. We’ll see!
Update Friday, February 16, 2024. Latest forecast for Los Angeles area suggest the rain may hold off until Sunday night or Monday.
I’ve encountered some interesting things crawling on the ground at Ahmanson Ranch this Fall.
Gopher snakes are the snake I see most frequently at Ahmanson Ranch (Upper Las Virgenes Canyon Open Space Preserve). Recently, I came across this sizable gopher snake crossing the dirt road on the long switchback above the Victory Trailhead. Despite the small size of its head, a gopher snake can consume prey much larger than might be imagined.
Just a few days ago — in virtually the same place as the gopher snake — I encountered a good-sized Southern Pacific rattlesnake serpentining across the dirt road and continuing up the brush-covered hill (video). The snake reminded me of a rattlesnake I photographed near the Victory Trailhead in November 2019. In the Fall, Southern Pacific and other rattlesnakes are said to return to the same den year after year. This rattlesnake had about 13 rattle segments, and the November 2019 rattlesnake about 10. Both were headed in the same direction. Might they be the same snake going back to a den?
On that same run as when I encountered the rattlesnake, I came across this remarkably colored and patterned caterpillar on Lasky Mesa. It turns out to be the caterpillar of a white-lined sphinx moth — a type of hummingbird moth.
A few days later — near the same place where I encountered the gopher snake and rattlesnake — I happened upon this tarantula scurrying across the road. Male tarantulas search for mates in the Fall.
Some related posts:
Ahmanson Trailhead Rattlesnake
Big Southern Pacific Rattlesnake at Ahmanson Ranch
Stuck in the Drive-Thru
September and October are Tarantula Months!
If It Looks Like a Hummingbird and Flies Like a Hummingbird…
It’s been about a month and a half since Tropical Storm Hilary soaked Southern California with record-setting rainfall.
The unusual amount of Summer rain has resulted in a second Spring at Ahmanson Ranch, with some plants behaving as if it were March or April.
Not only are plants growing as if it were Spring, some are flowering. The lupine pictured above usually blooms at Ahmanson Ranch in March, April, and May. Now, as a result of T.S. Hilary’s rain, it’s flowering in October!
Those plants that usually flower in the Fall, such as telegraph weed, vinegar weed, and common sunflower, are much more widespread than usual.
Spring-like conditions are present in many areas of Southern California. On Sunday, I ran the Phantom Trail in Malibu Creek State Park. Some sections were so overgrown that it was challenging just to navigate the trail, much less run it. Ticks were also a problem.
Some related posts:
Lake Vista Ridge, the Forest Trail, and September Wildflowers
Looking For Local Impacts of Tropical Storm Hilary
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 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.
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.
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!
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.
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.
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.
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