Everyone knows that wind fans fires, and almost everyone knows that the winds that matter are the howlers, which in Southern California means the Santa Anas. But a finer-grained scrutiny shows the same complexity for winds that characterizes terrain, fuels, and ignitions. In the South Coast big fires can occur without big winds. The winds that matter are those that push fires against cities or that trap firefighters. Straddling a tangle of mountains, the Los Padres National Forest illustrates that distinction decisively.
During a three year span, from 2007-2009, the LP experienced five major fires. Two giants loped over the backcountry, pushed and pulled by landscapes rugged with ridges and lumpy with chaparral. Three smaller burns slammed into high-value frontcountry. The three were an order of magnitude (and in two instances, two orders of magnitude) smaller than the large but they took out houses in a celebrity-studded coastline. That happened because winds spilled over the mountains and rushed downslope, even at night. Two landscapes, two kinds of fire behavior, two relationships to wind, and two kinds of fire – in Southern California wind is what makes big fires into great ones.
§ The LP sprawls over that granitic splintering where the Transverse Range breaks into a fan of lithic slivers – the Santa Ynez, the San Rafaels, the Sierra Madre. It then, with great gaps, continues leisurely up the Coast Range to Big Sur. Among the four regional ranges it has the largest fraction committed to wilderness (80%). It stands closest to the sea. And it displays the fullest assortment of winds.
There are the local winds – the land and sea breezes that are part of daily rhythms, that rise and fall over the land as tides do for the ocean. Mostly they bring maritime air and frequent fog. Daily, too, on the backside of the mountains, winds strengthen and falter as the sun heats and the evening cools; they interact with terrain and clumps of fuel to sent flames up chimneys, spin them through eddies and firewhirls, and quiet their spread at night. Overlying them are the synoptic winds that accompany fronts, or the rolling in and out of the region by high and low pressure cells. These, too, come from the west, or cause winds to veer from southwest to northwest, and they carry Pacific air to the crests of the mountains. Sometimes they supplement, sometimes they counter, the local breezes. This is all standard fire behavior with a California accent.
What makes robust fires into monsters are the winds that reverse this pattern and blow from the desert to the sea and from the crests of mountains to their bases. Where sea winds moisten, these desiccate; where slope winds rise and fall with the sun, these burn through the night; where normal fire can be flanked on ridges, these can spill over the levees and scatter embers with the abandon of a girandola. Such winds are not unique to Southern California. They belong to a category known, unimaginatively, as strong mountain downslope winds. They are the foehns of the Swiss Alps, the chinooks of the Rockies’ front range, the east winds of northern California and the Pacific Northwest. But nowhere else do they interact with such ferocity or last so long as at the South Coast.
The conditions that make them possible are hardwired into the regional terrain and the software of climate. Every autumn High pressure can stall over the interior basins of the West – on smaller scales, the Great Valley of Central California, or the Santa Ynez Valley – while Low pressure approaches from the southwest. The mountains stall the flow between them, and where the mountains are deep and high, and the pressure difference between centers is great, the gradient effectively steepens and the winds gush explosively. They flow over the mountains; dry, warm, gusting with the untrammeled sprawl of an avalanche or the floodwaters from a ruptured dam. In the Santa Anas the California tendency to exaggerate natural phenomena finds a meteorological expression. If a spark is anywhere around, flames take on the character of those winds. More insidiously, high winds can cause powerlines to break or arc and scatter sparks, thus adding ignition to their gallery of malevolence.
But the winds, even under Santa Anas, are not quite so simple. They are channeled by passes through the mountains, broken and funneled by ridges and ravines, diverted by summit spillways. And they interact with local winds: the bellows that bring prevailing winds from the west and the local generators lodged deep in mountain valleys continue, and the Santa Anas must beat against them, skip over them, or blow them locally away. One can weaken and the other strengthen – how they engage will scatter perimeter flames like leaves in a tempest and shape the contours of the burn overall. Still, there is a logic imprinted on the landscape, much as with floodwaters. There are patterns, although as with all matters Californian, from time to time the norm is meaningless, even when it involves the infrequent. What matters is the rare and the extreme.
§ To all this the Los Padres offers a local codicil. The Santa Ynez Mountains are a cameo of the Transverse Range, the coastal-front mountains for what appears as a granitic wave train. A deep valley behind, steep mountains against an urban complex – this is the South Coast formula in miniature. And what the Santa Ynez Mountains are to the Transverse Range, the Sundowner is to the Santa Ana.
By rushing down to the Santa Barbara coast at dusk the Sundowner winds seem to embody their name. The etymology is otherwise but uncertain. In one version it derives from the Spanish zonda (for foehn wind), while in another, from simoom, a version of scirocco (perhaps via Spanish). Or those may be attempts by the colonizing Spanish to render the Chumash term into something that sounded familiar. The one surety is that English-speakers converted the indigenous expression into something else that loosely related to the phenomenon as they experienced it.
The same seems to be true for its meteorological mechanics. In a loose way the Sundowner is a Santa Barbara Santa Ana. It relies on similar arrangement of air masses that causes winds to pile up against the north slope and then spill over the south toward the coast. As they rush down, they warm and dry. It may be that the Sundowner is what remains after air cascades from the north across the fan of mountain waves. Or it may be outcome of a mesoscale equivalent in which the California interior accretes air and a Catalina eddy tugs them south. In some cases the Sundowner effect means a dramatic rise in temperature (up to 107o). In others, it means a downslope wind particularly noticeable at night.
The history of Santa Barbara is a chronicle of Sundowner fires. Sediment from the channel holds charcoal through most of the Pleistocene. The American record begins when Richard Henry Dana recounted one such episode that dated from the 1820s. In August 1940 the San Marcos fire “provided a thrilling spectacle for the thousands of Santa Barbarans and outside visitors celebrating the annual Spanish Days festival.” Over the past few decades the fires have become less an entertainment and more a threat. The Refugio (1955), the Coyote (1964), the Wellman (1966), the Romero (1971), the Sycamore Canyon (1977), one after another, they burned swathes down the slopes of the Santa Ynez, rupturing along a biotic faultline, and all raised the stakes since the flames no longer passed through the rabbit habitat favored by the Chumash or the ranchlands preferred by Spanish and early Americans. On June 27, 1990 a Sundowner drove the Painted Cave fire through 4,900 acres, 427 homes, 221 apartments, 15 businesses, and 10 public buildings. In July, 2008 the Gap fire washed down toward Goleta and Isla Vista, half of the 9,544 acres on the Los Padres, half on private lands, upending watersheds. In November, 2008 the Montecito Tea fire blew through 1,940 acres and 210 houses, Westmont College, and the Mount Calvary Retreat House and Monastery. In May, 2009 the Jesusita fire rushed down Mission Canyon toward downtown Santa Barbara, taking out 8,733 acres, 80 houses and a commercial property.
The right wind on a smartly placed spark will spread. So, too, even a small fire, measured by geographic size, may spread widely through the culture if fanned by modern media. Such propagation requires as primary fuel not chaparral but celebrities. Actor Christopher Lloyd lost a home. Rob Lowe had to evacuate. Steven Spielberg evaded the flames. Oprah Winfrey was spared but broadcast her feelings on her show. Governor Arnold Schwarzenegger visited the burn.
Fire effects, that is, are no longer limited to air, soil, water, flora and fauna. With the right wind behind it a fire can blow ash across national TV. The Sundowner can not only leverage an ember into a conflagration, but blow up a local fire into a national story. It is not the vigor of the wind that matters. It is its ability to shake the right neighborhoods and, through its funneling down media channels, to be made visible.
July 2011 / [pdf]
Acknowledgements: I’d like to thank Andrew Madsen for allowing me to join a field trip to the scene of the La Brea fire, Chris Childers for a terrific tutorial on the fire and the Santa Barbara County fire scene generally, Celine Moomey for maps and data, and Anthony Escobar for his insights into fire on the Los Padres. I regret my abstract of an essay cannot give full honor to their understanding and assistance.