The sun comes up bright that day. It is a Friday — June 17, 1859. There is a little breeze from the northeast, a clear sky, and the promise of a warm day. 

But by noon, people begin to notice something unusual is happening. The temperature has quickly soared to almost 100 degrees, and the mountain breeze is becoming stronger and stronger. 

An afternoon blast of hot afternoon air sweeps through the Goleta Valley from the direction of Santa Ynez Peak, driving even the hardiest into the shelter of their homes and filling them with terror.

They think the end of the world has come. 

Will It Ever End?

By 2 p.m. the temperature is an incredible 133 degrees!

Many of the people take refuge behind the thick walls of the adobe belonging to Daniel Hill, the owner of Rancho La Goleta, where they pray fervently for the oppressive heat to be lifted. 

For the next three hours, the temperature hovers at 130 degrees; by 5 p.m., it has cooled off only slightly, to 122 degrees. Will this ever come to an end they wonder?

Simoon of 1859

Birds plummet dead from the sky; others had flown into wells seeking cooler air and drowned, Walker Tompkins write in his book, “Goleta the Good Land.” 

“Calves, rabbits and cattle died on their feet,” adds a government report. “Fruit fell from trees to the ground, scorched on the windward side; all vegetable gardens were ruined.”

Did this really happen? Just another one of Tompkins fanciful stories? Or one of the first recorded sundowner events to strike the Santa Barbara  coastal areas?

Power of the Wind

There are no doubters among those who are here in Santa Barbara on Wednesday, June 27, 1990, when the Painted Cave Fire starts and the temperature is a sizzling 108 degrees. 

The fire, which is started by an arsonist near the intersection of Painted Cave Road and Highway 154, comes down the mountainside like a speeding locomotive. Powered by hot 50 mph winds, the flames torch everything in their path. 

The awful roar of the approaching firestorm can be heard from a distance of more than five miles, the sheets of flames sweeping along the mountainside and leaping high in the air.

Near what is known at Windy Gap, one of the Los Prietos Hot Shot crews stops to give aid to a woman in her VW Beetle and a man in a pickup truck.

Follow Me

“Follow me,” the crew leader tells them. “Whatever you do, stick right on my tail and don’t let me out of your sight.” 

They struggle on through the smoke, but only make it about a quarter of a mile when the flames begin to surge up over the road in front of them. Finally, they stop, unable to see anything but a fiery red wall of flames.

Later current Santa Barbara County Fire Marshall Rob Hazard — who is one of those in the crew truck — tells me he was sure they would die that night.

All survive when the fast moving flames move by quickly.

Then Tragedy Strikes

Unseen below them, a 37-year-old woman is home alone. She and her husband had moved into the foothills to experience a more natural lifestyle.

“We had come to appreciate the beauty of the wild areas here,” her husband says later.

When the fire begins, Michael, a photographer and designer, checks in with Andrea, to be sure she is okay. Without a car to use for escape, she decides to flee on foot but is overcome by the smoke and makes the decision to duck down into a low gully for protection.

When the flames descend towards her, she never has a chance. The next day, her body is found just a few hundred yards from her home.

The Fire Triangle

Firefighters will tell you that it takes a combination of factors for the big, destructive fires such as the Paint or Sycamore or Jesusita or Tea fires that Santa Barbara has experienced over the past several decades.

These factors include fuel, topography and weather.

But they also know that the most dangerous and life-threatening of these occur when a weather-related phenomenon known as a sundowner occurs. 

Amazingly, they exist almost exclusively along the Santa Ynez Mountain range.

Downslope Weather Event

At a minimum, they’re powerful enough to knock down power lines, scatter outdoor furniture or ruin a beachside picnic.

At their most powerful, they are capable of carrying a wildfire from the mountaintop to the edge of town in less than an hour. Or turn a wildfire burning out of control up the mountainside and back down into the urban areas at the blink of an eye.

They can also kill — or cause the destruction of scores of homes — in less time than it takes to watch a full-length movie.

“If you live on the southern slopes and foothills of the Santa Ynez Mountains, you probably have experienced the gusty and dry winds that show up in the late afternoon or early evening,” UCSB Professor Leila Carvalho explained to me.

Having almost lost the place I rented along East Camino Cielo during the Paint Fire, I understand completely.

Understanding How Sundowners Behave 

Sundowners have been Carvalho’s primary research focus for a number of years as a part of her work at the Department of Geography’s Earth Research Institute.

Several years ago, she was able to obtain grant funding from the National Science Foundation for a project designed to understand the dynamics of downslope winds — known locally as sundowners — on the south-facing slopes of the Santa Ynez  Mountains.

Titled the Sundowner Winds Experiment (SWEX), its goal is to develop a better understanding of when and where sundowners will occur, and give firefighting agencies critical data for where to stage equipment and manpower during periods of high fire potential.

Building a Sundowner Model 

If you were asked to build the perfect topography for a sundowner event, it might look something like this.

You would want to start with an east-west mountain range like the Santa Ynez, and place it in close proximity to the Pacific Ocean. 

You’d also make the front-facing slopes extremely steep and close enough to the ocean that its cooler waters would create extreme pressure differentials between them and the hotter inland air on the other side of the mountains.

You’d also add a secondary inland range like the San Rafael Mountains, with an open valley like the Santa Ynez in between, effectively creating a closed box canyon leading up the Santa Ynez River, perfect for concentrating that hotter air.

Finally, you’d tack on high pressure areas like those that develop in the Santa Maria basin or the southern Central Valley near Bakersfield to accelerate the movement of high pressure air up the river or over the San Rafael Mountains.

The result: almost ideal topography and physics for the the development of sundowner type winds.

Checking Airport High and Low Pressures 

“We have a general understanding of when conditions are right for a sundowner to develop,” Carvalho tells me as we sit in her office on the 6th floor of Ellison Hall. 

There are basically three types of sundowner regimes, she explains to me.

“Western sundowners will occur when there is a major difference between air pressure at the Santa Maria Airport and that at the Santa Barbara Airport,” she points out, “This will concentrate higher pressure differentials along the western part of the Santa Ynez Mountains.

“When there is a similar difference between the air pressure at the airports in Bakersfield and Santa Barbara there is a higher potential for what we call the eastern sundowners.”

The third regime combines a mixture of both, with the winds picking up first in the west and later in the evening on the eastern part of the Santa Ynez Mountains.

Carvalho considers high pressure air flowing in from the east to be of the most serious concern given that it impacts the canyons immediately behind Santa Barbara and Montecito, where the mountains are the steepest and the potential for strong air flow down them is the greatest.

Developing a Model Not So Easy

But while understanding the topography of sundowners and why they occur here and virtually nowhere else may be reasonably easy, creating a model to predict exactly when or where a sundowner will occur or to what intensity one will develop is not so simple.

Pre-staging personnel and equipment is key to the quick fire-response times needed in such a fire-prone environment as we have here in Santa Barbara.

Weather modeling has come a long way in providing the data needed to predict the probability a fire will occur, and vegetation modeling has allowed us to understand which areas are most prone to carry a fire.

Knowing how to predict which of the scores of passes, saddles and gaps along the Santa Ynez Mountains the high pressure air will be most vulnerable to a sundowner is not so easily done.

But working out the details is absolutely critical to protecting Santa Barbara from the next destructive and possibly deadly wildfire.

Virtually every major fire ranging from the Sycamore Fire in 1977, to the Paint Fire in the 1990s and the Jesusita, Tea, Holiday and Thomas fires in the past 15 years has been sundowner driven.

That’s where the work Carvalho is doing comes in.

When Things Get Tricky

Over the past two years, the SWEX grant has provided the funds to deploy both fixed and mobile LIDAR stations, launch weather balloons, and use fixed-wing aircraft to fly cross sections of the Santa Ynez Mountains.

Carvalho points to an image on her computer screen of data they’ve collected from the aerial flights.

It shows what looks like a blue wave rising up from the valley side, curving over the mountaintop and then gliding down the front side.

“We call these mountain waves,” she tells me. “The blue represents a narrow band of much drier, warmer air.”

To my untrained eye, I’m assuming that I’m seeing what a sundowner wind actually looks like. But she cautions me, “not so quick.”

Though not so visible, she explains, the flow also includes bands of hotter and cooler air, creating a much more complex set of conditions than one might envision.

Then Carvalho traces the mountain wave as it flows down the mountain side to a point where it becomes somewhat disrupted with a noticeable drop in temperature and increase in humidity.

The blue wave has just met the marine layer.

“That is something we did not expect,” Carvalho tells me.

“What it does indicate,” she adds, “is that the marine layer may play a much larger role in determining how impactful sundowner winds coming from the valley will be.”

While it appears we are a few steps closer to understanding what additional research will be needed and where to focus it, breaking the code of the elusive sundowner effect still has a ways to go.

Reverse Engineering the Data

Ultimately, it may be that using the vast weather resources available combined with the data now being collected through the SWEX project will provide the tools needed to perfecting the ability to reverse engineer known sundowner events for use in modeling future ones.

Could this lead to the development a database of models used to predict future events?