Category Archives: weather

nature, trails, trails|smmc open space, weather, weather|southern california

Chumash Trail – Sesnon & Simi Fires

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Scorched yerba santa along the Chumash Trail.

This weather worn sandstone boulder is a familiar landmark to those who do the Chumash Trail. It’s a little less than a mile up the trail, and is at the point where the trail turns east and continues its climb along a cobble strewn divide. The chaparral here and elsewhere along the Chumash Trail was burned last week by the western front of the Sesnon fire.

In the areas bordering the Chumash Trail, the Sesnon Fire appears to have been much less intense than the 2003 Simi Fire. In the case of the Simi Fire, it had been about 15 years since the area was burned, the fuel load was moderately high, and the fire intensity was such that nearly all plant materials were consumed down to the mineral earth.

Recovery from the Simi Fire has been primarily through the slow processes of basal-sprouting and seed germination. Just prior to the Sesnon Fire, common chaparral plants such as chamise, yerba santa, toyon and holly-leaved cherry had recovered about 70% to 90% of their 2003 size.

The recency of the Simi fire appears to have reduced the fuel load available to the Sesnon Fire. In many cases grasses and other annuals (many invasive) were consumed, but adjacent chaparral shrubs were only scorched. Many of these shrubs look like they will probably be able to recover through foliage replacement, rather than crown-sprouting. One exception might be laurel sumac, which appears to have been less fire tolerant.

Update 12/23/08. Only a small percentage of the scorched Yerba Santa are recovering through direct foliage replacement. Most of these plants are recovering through the process of crown sprouting.

In addition to reducing the fire danger, a little light rain would help jump start the recovery process. Computer weather models have been hinting at a change in the weather around November 1, and now seem to be converging on the possibility of a shower in Southern California around Halloween, followed by a front and some rain later in the weekend. That’s still a week away, so we’ll have to see!

Here’s a Google Earth image and Google Earth KMZ file of the perimeters of the Sesnon and Simi Fires, as well as GPS traces of some of the trails in the area.

nature, nature|trees, photography, photography|quirky, weather

Mt. Hawkins Lightning Tree

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An unusual, offset lightning scar on a Jeffrey pine in the San Gabriel Mountains, near Los Angeles.

An unusual, offset lightning scar on a Jeffrey pine in the San Gabriel Mountains, near Los Angeles. The tree is located at an elevation of about 8750′, on the ridge east of Mt. Hawkins.

The offset scar is not easily explained. Either the scar was offset when created, became offset as the tree aged, or perhaps multiple strikes have somehow created the appearance of an offset. None of these explanations seem completely satisfactory.

The lightning scar on the Mt. Hawkins tree appears to be older than the scar on the Jeffrey pine on the Three Points – Twin Peaks Saddle trail, and quite a bit older than the scar on the Jeffrey pine on Mt. Baldy’s North Backbone Trail.

Google search: $g(lightning)

nature, nature|trees, photography, photography|landscape, weather

Did Lightning Start the 2002 Curve Fire?

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Or did the Curve Fire trigger a lightning strike?

These trees — on a section of the Pacific Crest Trail east of Windy Gap — were burned almost six years ago in the 20,857 acre Curve Fire. According to the Curve Fire Burned Area Emergency Report Implementation Plan, the source of ignition for the devastating fire was “a ritual involving the use of fire (candles) and animal sacrifices.” The fire started the afternoon of September 1, 2002.

However, in the document An Exercise Involving Flash Flood and Lightning Potential Forecasts, an alternative ignition source was suggested — an “out of the blue” lightning strike. Forecasters observed a “single positive lightning strike northeast of the Mount Wilson Observatory” about 1:00 PM PDT (2000Z), near the time the Curve Fire started. According to NWS Lightning Safety Outdoors, such bolts from the blue have been documented to travel more than 25 miles from a thunderstorm cloud.

While there is compelling evidence that the blue sky lightning strike occurred, the time of the strike suggests that it was not the initial source of ignition of the Curve Fire. This UCLA Solar Towercam image is time-stamped at 12:58:58, about the time of the strike. It shows the Curve Fire already underway, with a well-developed smoke column. The photograph also shows the cloud development over the San Gabriel Mountains.

An intriguing question comes to mind. Was the lightning strike a coincidence, or was it somehow triggered by the fire, or the smoke?

According to “Forest Fires: Behavior and Ecological Effects” by Edward A. Johnson, Kiyoko Miyanishi (Academic Press, 2001) large scale lightning detection networks have revealed an association between forest fires and the electrification of thunderstorms. Further, “a shift from negative to positive ground flash prevalence in association with fires and forest fire smoke” has been documented.

So it looks like lightning did not start the Curve Fire, but the Curve Fire may have triggered the positive lightning strike observed by the NWS!

The photograph of trees burned in the Curve Fire is from Sunday’s Islip Saddle – Mt. Baden-Powell South Fork run.

Related post: Explosive Growth of the Lake Fire

Technical papers:

CLOUD-TO-GROUND LIGHTNING DOWNWIND OF THE 2002 HAYMAN FOREST FIRE IN COLORADO

Timothy J. Lang* and Steven A. Rutledge
Colorado State University, Fort Collins, Colorado

Enhanced Positive Cloud-to-Ground Lightning in Thunderstorms Ingesting Smoke from Fires

Walter A. Lyons, Thomas E. Nelson, Earle R. Williams, John A. Cramer, and Tommy R. Turner
Science 2 October 1998 282: 77-80 [DOI: 10.1126/science.282.5386.77] (in Reports)

nature, nature|clouds, nature|weather, photography, photography|landscape, running, running|adventures, trails, trails|san gabriels, weather, weather|southern california

Three Points Loop Plus Mt. Waterman

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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.

Take this weekend for example. I have a 50K race coming up, and in addition to increasing my weekday mileage, I needed to do a Sunday run of about 20-25 miles — preferably in the mountains.

The Sierra was out. A monsoon pattern virtually assured widespread, and possibly severe, thunderstorms. Some forecast models were saying that the focus on Sunday might be the Ventura County mountains, so Mt. Pinos — the site of my most recent thunderstorm adventure — was also out. Both San Gorgonio and San Jacinto had been hit pretty hard on Saturday. That left the San Gabriels, and thunderstorm activity was expected there as well.

The choices were A — get up really early and try to beat the heat and humidity and run local; or B — get up really early and try to get in a mountain run before the weather OD’d…

Running up the Mt. Waterman Trail, one of my ever-optimistic running partners voiced, “Hey, have you heard about the unusual number of lightning deaths recently?” So far it had been a spectacular day. A broken layer of mid-level clouds — remnants of yesterday’s storms — shrouded the sky. By keeping things a little cooler, the clouds had delayed the development of today’s thunderstorms.

We had started at Three Points and run up the Pacific Crest Trail to Cloudburst Summit, then down into Cooper Canyon, where we left the PCT and ascended the Burkhart Trail to Buckhorn Campground. In Cooper Canyon it was obvious there had been heavy rain the day before. Everything was wet, and the willows and lupines along the creek glistened in the muted morning sun. Rivulets of rainwater had incised rills in the trail, pushing pine needles and other debris into patterned waves.

I had already lost the “when it would start raining” bet. I had said 11:00. It was 11:00 now, and still there was very little cloud development. So little in fact, we decided to do a quick side trip to Mt. Waterman (8038′), and jokes were being made about the rain gear in my pack. (My GoLite 3 oz shell made a huge difference in the severe thunderstorm on Mt. Pinos.)

About the time we summited Waterman, things started to cook. The canopy of protective clouds was beginning to thin and dissipate and some cumulus cells were starting to build. I wondered if we would make it back to the car before it dumped.

We didn’t. About 30 minutes later, as we worked down the back side of Mt. Waterman toward the junction with the Twin Peaks trail,  we heard our first grumbling of thunder. In another 30 minutes it started to rain; slowly at first, with large icy drops, then building in intensity, as prescribed in long established thunderstorm protocols. Periodic claps of thunder echoed overhead, and to the north and east.

About 3 or 4 miles of trail remained. Here, the trail winds in and out of side-canyons and for the most part is well below the main ridge, but at some points it is very exposed. Minutes before, we had run past a lightning scarred Jeffrey Pine. Burned and blackened, the bolt had killed the tree. I pick up the pace and try to put the tree out of mind.

It rained hard for a while and then the intensity diminished. The air temperature didn’t drop and the wind wasn’t strong. It seems most of the lightning is cloud-to-cloud and away from us. I’m drenched, but happy — instead of being fierce and frightful, this thunderstorm has been almost puffy-cloud friendly.

In steady rain, we cross Hwy 2 and jog up the trail toward the Three Points parking lot (5920′). As we near our cars, we’re startled by a loud boom of thunder directly over our heads — a not so gentle reminder that thunderstorms come in all sizes, and none come with a guarantee.

Here’s a Google Earth image and Google Earth KMZ file of the loop, including the side trip to the summit of Mt. Waterman.

Some related posts: Manzanita Morning, Three Points – Mt. Waterman Loop

photography, photography|landscape, weather

Blame it on Cristina

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View of Bench, Matlock and Slim Lakes from the north face of University Peak.

We were making good progress up the gargantuan north face of University Peak (13,632′), climbing carefully and doing our best not to knock loose rocks down on each other’s heads. We were also doing our best to ignore the gathering clouds — and the unnerving rumble of distant thunder.

Yes, it would have been better to sleep at the trailhead and get an early start. Especially with a 20% chance of isolated thunderstorms in the forecast. But we didn’t. When we should have been taking our first steps on the Kearsarge Pass trail we were eating breakfast burritos in Mojave. So it goes.

Now we were about half way up the 2200′ class 2-3 face, and it would take another hour of climbing to reach the summit. That would put us on the summit right around the time of maximum daytime heating — a bad time to top out if you’re trying to avoid a thunderstorm.

Off to the northwest there was another long, rolling, rumble of thunder. Streamers of rain could be seen twining from darkening clouds. Smoke from one or more of California’s many fires hung in the valleys to the west of the crest, producing an unnatural and eerie mixture of clouds, smoke, rain, and orange tinted terrain.

We paused in a jumble of broken blocks of granite, hemming and hawing, and otherwise hesitating to make THE decision to descend. Avoiding the issue and pondering the sky, we wondered which fire the smoke was coming from, and — half in jest — whether the smoke could have seeded and enhanced the thunderstorm we were watching. Those questions, it turns out, had surprising answers.

I had assumed the smoke was from one of the fires to the west. But this NRL Aqua-MODIS True Color satellite photo from 1:38 in the afternoon reveals the source of the smoke — it was from the Piute Fire between Lake Isabella and Tehachapi. The long plume of smoke from this fire feeds almost directly north into the large thunderstorm cluster near 37N and -118.5W.

From our vantage point on University Peak, the southern margin of this activity appeared to be about 6 miles away, somewhere near Gardiner Basin. This experimental NRL image shows the convection more clearly. Could this smoke plume have enhanced the storms over the Sierra?

The research article “Smoking Rain Clouds over the Amazon” by M. O. Andreae, et al, published in Science Magazine in 2004, and related research, suggests the possibility. According to that article, vegetation burning produces high concentrations of aerosols which are capable of nucleating cloud droplets. But, convective clouds forming in smoky air show substantially reduced droplet size compared to similar clouds in clean air. The reduced droplet size can delay the onset of precipitation, which in turn can result in enhanced convection.

So why blame the thunderstorm on Cristina? This NRL water vapor satellite photo from 3:30 p.m. suggests that the source of the moisture for the Sierra thunderstorms was Tropical Storm Cristina. An upper level low spinning off the coast had drawn the moisture up from the tropics and into the Sierra.

Related post: Thunderstorm, Shadow and Sun on University Peak (The north face is highlighted by the sun.)

photography, photography|landscape, trails, trails|smmc open space, weather, weather|southern california

Eagle Rock – Topanga State Park

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Eagle Rock in Topanga State Park.

Mammoth Mountain reports more than a foot of snow fell over the Memorial Day weekend but that translated to cool, puffy white clouds and blue sky weather in the Los Angeles area, seldom seen this late in May.

Taking advantage of the great weather on Sunday my son and I ran the Garapito figure-eight course in Topanga State Park.  We did a slight variation that climbs Eagle Rock before descending the Garapito Trail.

Gov. Schwarzenegger’s revised state budget, released May 14, rescinded the funding cuts that would have closed 48 California state parks, including Topanga State Park. For now, it appears these state parks will remain open.

Some related posts: Eagle Rock Silhouette, Eagle Rock and Clouds