Edgar McGregor

Over the past 116 years of weather record keeping, there have only been six cases of back-to-back winters in Eaton Canyon in which more than 25.00″ fell. These back-to-back wet winters are exceptionally important for the biodiversity of Eaton Canyon as some plants and animals depend on occasional prolonged wet periods to thrive, not just survive. Contrary to popular belief, the Western U.S. Megadrought is not over in California whatsoever. Megadroughts are defined as 20+ year long periods with below average precipitation, high temperatures, low humidity levels, decreased soil moisture levels, increased wildfire threat, significant forest mortality, groundwater depletion, irreversible land subsidence, weakened food chains, and threatened biodiversity. One single ultra-wet winter in California is not enough to repair the damages caused by this megadrought. Until the ecological damages can be somewhat repaired, this megadrought is not over. In order for California to escape from this megadrought, 3-5 years of back-to-back wet winters must occur in the state. These back-to-back wet winters we are looking for in California occurred in Eaton Canyon in:

• 1937, 1938 and 1939 (3 wet winters in a row)
• 1943 and 1944
• 1966 and 1967
• 1992 and 1993
• 2010 and 2011 
• 2023 and….. 2024?

The El Niño Southern Oscillation, or ENSO, is a periodic and regular shift in oceanic sea surface temperatures (SSTs) along the equatorial east Pacific ocean from the area south of Hawai’i eastwards to the west coast of Peru. ENSO does not occur anywhere else in the world, only in this one region. When ENSO is in its negative phase and sea surface temperatures are cooler than average, we call this La Niña. When ENSO is in its positive phase and sea surface temperatures are above average, we call this El Niño. Given the expansive aerial extent of this periodic phenomena, climatologists have noticed a pattern emerge with each ENSO cycle within weather conditions worldwide. In California, El Niño typically means heavy winter rains while La Niña typically means less winter rains.

According to TropicalTidbits.com, we are currently in moderate El Niño conditions with SSTs +1.3°C across the equatorial east Pacific. NOAA has issued an ‘El Niño Advisory’ with a 85% chance of this event turning into a strong El Niño (SSTs >1.5°C) and a 30% chance of turning into a historically strong El Niño (SSTs >2.0°C).

The connection between wet winters in California and El Niño exists because El Niño steepens the temperature gradient between the North Pacific and the Equatorial Pacific. This steeper gradient strengthens the subtropical jet stream, a weaker counterpart to the polar jet stream. When the subtropical jet stream is stronger, it is able to undercut more wintertime ridges of high pressure that would normally sit off the coast of California and block any rain storms coming in. Instead of pushing these ridges aside like when the polar jet stream is amplified, an amplified subtropical jet stream simply pushes the ridges northwards, allowing warm Pacific storms with a strong tropical moisture tap to sneak into California. As a result, El Niño winters are typically not great winters for low elevation snowfall in California. It is those winters with a strong polar jet stream, like 2023, that can bring tons of low-elevation snow throughout the state.

Not all El Niño episodes are created equal, and there is no shortage of examples in which El Niño conditions failed to bring decent winter rains to California. There are other meteorological factors at play all across the globe, one of them being pure luck. For many California weather enthusiasts, the colossal failure of winter 2016’s rainy prediction pains us to this day. Hopefully this time we are not hyping ourselves up again only for it to be 90°F throughout much of February.

Winter 2024 is expected to be wetter than average in Eaton Canyon. Just how wet remains to be seen, though it is unlikely we will get another 43″ of rainfall like we did last winter. There is also no knowing if any storm will produce high enough rain rates to ecologically destroy Eaton Creek, which was destroyed and reordered in 1938, 1943, 1969, 1980, and 2005. Without a recent canyon-wide wildfire in Eaton Canyon, such a storm is unlikely in any given winter, though they are most likely in El Niño winters

Eaton Canyon, like much of Southern California, has evolved over millions of years to become accustomed to wildfire. Numerous plant species, including the Chaparral Yucca, Manzanita, California Buckwheat, and California Sagebrush, are all adapted to survive ferocious wildfires. Some native plant species, including the Fire Poppy, specifically need wildfire in order to clear out competition. Meanwhile, the native Coulter Pine found in upper Eaton Canyon needs wildfire in order to break open their pine cones and release their seeds. Wildfire has become a critical component to our local ecosystems over eons, though that hasn’t made it easier to watch these natural spaces experience such a massive disturbance.

In the early morning hours of October 27, 1993, Andres Huang, 35, started a campfire in a small pine forest along the Mount Wilson Toll road to keep warm. Huang was a homeless man suffering from undiagnosed schizophrenia. Given heavy fuel loads in the area, this campfire quickly spread to nearby brush. By the time anybody else noticed the fire, it had already jumped into a nearby canyon and Huang had fled. The first call was received by Station 66 at 3:48 AM. It is unclear how long the fire went unnoticed.

For the first hour of the Kinneloa Fire, the blaze mostly spread uphill towards Henninger Flats while slowly backing down hill towards Altadena and lower Eaton Canyon. Just before 5 AM, however, the Santa Ana winds kicked in and the fire quickly took off. Relative humidity levels plummeted, temperatures rose despite it being nighttime, and winds of 40 MPH quickly fanned the flames to blow into lower Eaton Canyon. The Los Angeles County Fire Department quickly responded to the incident in fear of a much larger event. Incident command was established at the Midwick Trailhead as the fire began to race towards Altadena and Kinneloa Mesa. Initially, the fire spread southward down hill towards Eaton Wash. Coyote Canyon and Walnut Canyon were burned first. At around 5:30 AM, the fire reached the bottom of Eaton Canyon, destroying chaparral and riparian habitats. The fire also moved along the Mount Wilson Toll Road, trapping 15 firefighters who had to deploy their fire blankets.

At 5:45 AM, the wildfire reached Altadena Dr., and the Midwick incident command was briefly relocated to the Eaton Canyon Nature Center. Just after 6 AM on October 27, 1993, the Eaton Canyon Nature Center was brought to the ground and the incident command relocated to Victory Park. Built in 1963, the original Eaton Canyon Nature Center was a classic mid-century modern building named after the local civic leader Robert McCurdy. It burned near its 30th anniversary after being built.

The Kinneloa Fire erupted from here on, destroying 121 homes in the Altadena, Pasadena, and Kinneloa Mesa communities. Palm trees beside St. Luke’s Medical Center began to catch fire as embers rained from the sky throughout eastern Pasadena. The fire rose up from Eaton Wash to Kinneloa Mesa in just 90 seconds, causing multiple homes to go down in flames. The fire also jumped the mouth of Eaton Canyon and began racing westward along the Altadena Crest Trail. The Kinneloa Fire was able to burn homes as far away as Glen Canyon to the east and Zane Grey Terrace to the west. In the end, 5,485 acres were torched, 196 structures were destroyed, and 38 people were injured. There was 1 direct fatality, and 2 indirect fatalities. Multiple other fires began that day throughout Southern California in what is now known as the 1993 Southland Firestorm. 

Over a week later on November 9th, 98-year-old Alfred Wagner died of pneumonia caused by smoke inhalation. In March 1994, a flash flood that tore down Bailey Canyon in Sierra Madre killed 33 year old John Henderson and his 9 year old son, Matthew. The flash flood was made significantly more lethal by the scorched landscape which was unable to absorb water.

The 1993 Kinneloa Fire remains the most recent fire to thoroughly burn Eaton Canyon to this day. In 2009, the Station Fire was able to burn the western quarter of upper Eaton Canyon, though the fire was not severe and left most trees alive. There have been many small fires since then, including a 1-acre blaze below the Midwick trailhead in February 2018. After 30 years of no major fires, Eaton Canyon is one of the most fuel-dense areas of the Angeles National Forest. Upper Eaton Canyon beyond Idlehour Campground did not burn in 1993, and the last fire there was the Pinecrest Fire in 1979. It is a question of when, not if, the next wildfire will destroy Eaton Canyon. As we have learned from the towns of Paradise, Santa Rosa, and Lahaina, a significantly worse wildfire than the Kinneloa Fire is very possible in Altadena.

In 1995, a severe storm set a wall of mud thundering down Moist Canyon, burying parts of Eaton Wash in up to 15 feet of mud. This debris flow pushed Eaton Creek to the Nature Center side of the wash where it remains today. The large alluvial plain created by this flood can also still be seen today. The 2005 flood was made worse by the 1993 Kinneloa Fire, though 12 years of fuel growth prevented more serious flooding. The next wildfire will prepare any major storm over the following 15 years to completely reorder Eaton Wash.