Posts

Showing posts from December, 2011

The Great Basin

Defined by its hydrology, the Great Basin is a large area of the American West within which the rivers and streams drain from an irregular ring of topographic divides toward the interior of the basin, never to reach the sea. The west edge of the Great Basin runs along the crest of the southern Cascades, the Sierra Nevada Range, the Tehachapi Range and the San Bernardino Mountains while the east edge follows the crest of the Wasatch Plateau and the westernmost Uintas. Along its northern boundary, an irregular, low divide separates the watersheds of the basin rivers (dominated by the Bear and Humboldt Rivers) from that of the Snake River. The southern edge of the Great Basin is even more complex, separating basin river watersheds from that of the Colorado River, extending southward into northwest Mexico.

Since the Great Basin is surrounded by topographic divides, winds are downsloping from all directions, warming and drying the air; as a result, the Basin floor, with elevations rangi…

An Extreme Weather Year

By all accounts, 2011 has been a year of extreme weather across the U.S. Severe flooding in New England, a catastrophic drought across the Southern Plains, the worst tornado outbreak in recorded history, massive haboobs in the West and destructive wildfires across Texas have all dominated the headlines.

While years like this spawn doomsday discussions about the viability of our ecosystems, the threat to agriculture and the future welfare of mankind, they have no true predictive value. Though a backdrop of global warming cannot be ignored, these outbreaks of severe weather are more directly related to stagnant weather patterns, atmospheric derangements that often produce adjacent extremes of heat and cold, deluge and drought etc. A warmer climate may add fuel to the fire but the events themselves are sporadic; the last comparable episode of tornadic activity was in 1974 (almost 40 years ago) and the disastrous hurricane season of 2005 has since been followed by rather tepid years fo…

Pileated Woodpeckers

Most birders can easily remember their first sighting of a pileated woodpecker, especially due to their large size and distinctive markings; for me, this occurred along a country road near Wilmington, North Carolina. Though these woodpeckers are fairly common throughout much of their range, they prefer mature forests and are not often seen by the casual suburban birdwatcher.

Pileated woodpeckers inhabit forested areas of the eastern U.S., southern Canada, the Northern Rockies and Pacific Northwest; other than the rare and possibly extinct Ivory-billed Woodpecker of southeastern swamp forests, pileateds are the largest woodpeckers in North America. Adult pairs are monogamous and may remain together for a decade or more. Each spring, the pair excavates a new, oval-shaped tree cavity in which to raise their brood of 3-5 young; both parents incubate the eggs and, once fledged, the offspring will remain with their parents until autumn. The male often uses the nest cavity through the fo…

Moon over Venus

Last evening, a crescent moon gleamed in the southwest sky, its southern point tipped toward the horizon. Below the moon was Venus, its position suggesting a bright ornament hanging from and tilting its larger companion. This, of course, was an illusion, a product of my vantage point and the distance of those heavenly bodies from Earth. In fact, Venus has a diameter of 7521 miles, more than three times that of the moon; however, at its closest approach, Venus is 25 million miles from Earth, more than 1000 times the distance from Earth to the moon.

Such astronomical illusions have confused humans since our earliest days, leading us to see relationships among the stars and planets that don't actually exist. Indeed, many of the named constellations consist of stars that are farther from one another than each is from the Earth; their grouping in the night sky is merely a consequence of our own location in space. For astrologists or other pseudo-scientists to make predictions base…

Coffins: The Final Insult

The chemicals of life initially formed in a supernova explosion, fusing hydrogen and helium atoms to produce the "heavier" elements; these, in turn, combined to form molecules, the building blocks of all substances on Earth. The origin of life coincided with the appearance of DNA, which governs the assembly and function of all organisms, from bacteria to humans. Human DNA is the product of 3.6 billion years of DNA evolution, altered by random mutations, the incorporation of DNA from viral agents and countless recombinations of chromosomal DNA through sexual reproduction, all acted upon by natural selection.

Human DNA does not represent the endpoint of evolution but, rather, the current tip of one branch on the complex tree of life. Furthermore, our ability to live and reproduce on this planet is dependent upon the products of other life forms, most notably the oxygen released by photosynthesis and the nutrients provided by the various plants and animals that we consume. …

Birding in Context

Though I have been a birder for more than 35 years, I have never been one to chase after rare birds or to plan my vacations to add species to my life list. Nor am I crazy about group birding or bird related sporting events such as a "Big Year."

As a naturalist, I enjoy watching birds within the context of their natural habitat, observing their interaction with plants and other animals and coming to understand how they contribute to the function of that ecosystem. Whether the setting is a barrier island, a mountain forest, a rolling prairie or a suburban neighborhood, birds play important roles, as foragers, hunters and potential prey. Furthermore, since many species are migratory, their unique contribution is often seasonal, either as temporary residents or as transient visitors.

Like other creatures, birds are far more interesting than items on a checklist and we cannot truly appreciate their importance without recognizing their vital role in maintaining the health of na…

Humans, Faith & the Universe

Christmas is a meaningful observance for members of one religion on one planet in our vast Universe. Since the Universe harbors trillions of suns, it is safe to assume that there are at least millions of planets similar to Earth, many thousands of which are inhabited by humanoid populations similar to our own. With that probability in mind, one wonders whether the simplistic beliefs associated with Christmas are universal or purely a fabrication of human thought, creativity and culture.

Most human societies support religious freedom as long as those groups or intstitutions do not impose their beliefs on others or invoke those beliefs to abolish or restrict the rights of others. Unfortunately, the indoctrination of innocent children with religious faith, often reinforced by guilt and fear, is a common practice in human society and seems to acknowledge the fact that mature, experienced and educated adults may not be as receptive to such beliefs.

Religous faith is clearly distinct fro…

The Common Good

The Christmas Holiday Season, more than any other time of year, highlights the horrendous disparity between the American socioeconomic classes. While the wealthy shower one another with extravagant gifts and engage in excessive consumption, the poor can barely make ends meet, often forced to choose between holiday gifts and the staples of survival.

In my judgment, the wide gulf between rich and poor in this country reflects the distorted priorities of our economic system. The pay structure of corporate executives is based on profit margins, not on job creation or the social value of their goods and services. At our universities, where the cost of tuition is becoming formidable, football coaches are paid more than ten times the salaries of the best professors. And, throughout our society as a whole, we reward entertainers, athletes and other celebrities far out of proportion to their value to society.

The stories of Christmas, from Bethlehem to Scrooge to It's a Wonderful Life,…

The Desert Raccoon

Natives of Central and South America, coatimundis have spread into the Sonoran and Chihuahuan Deserts of the southwestern U.S. Formally known as white-nosed coatimundis, these members of the raccoon family, unlike their more widespread and familiar relatives, are diurnal and gregarious, often moving about in noisy bands composed of females and their young.

Adult males, twice as large as the females, weigh up to 25 pounds and tend to be more solitary. Mating occurs in the early spring and 4-6 young are born after a gestation of almost 3 months. Females often use rock crevices for nursery dens but she and her offspring later use crude arboreal platforms for sleeping and resting. Wandering about for much of the day, these omnivores locate food and prey with their long, tapered snout; insects, lizards, eggs, nuts and fruit comprise most of their diet. Coatimundis are agile climbers, equipped with sharp claws to grasp limbs and a long tail for balance.

Favoring wooded canyons of the D…

Ice Age Relics

Mention Ice Age relics and most of us think of frozen mammoth carcasses, unearthed Neandertal bones or that living relic, the musk ox. More sophisticated students of natural history might also picture various forms of glacial terrain, erratic boulders or relic groves of hemlock, surviving the warm Holocene in shaded valleys of the Temperate Zone.

In fact, most modern plants and animals lived during the Pleistocene, having "moved" to warmer latitudes or to deeper waters when glaciers advanced and sea levels fell. Of course, the colder and wetter climate of the Pleistocene also spawned the evolution of new species, such as polar bears and Arctic fox, as their ancestors adapted to changing conditions.

We humans are also children of the Pleistocene, having appeared about 130,000 years ago, late in the course of that 2 million year Epoch. Like other creatures, we adapted to its shifting climate but, due to our large brains, we did not require new physical traits to survive; ra…

Kofa NWR

If you enjoy an escape to the Desert Southwest during the winter months but hope to avoid the congestion of large cities and National Parks, consider a visit to Kofa National Wildlife Refuge, northeast of Yuma, Arizona. This extensive preserve (over 665,000 acres) was set aside in 1939 to protect habitat for desert bighorn sheep; more than 80% of the refuge is designated wilderness and it thus harbors some of the most pristine Sonoran Desert landscape in the U.S.

Stretching between the Kofa Mountains on the north to the Castle Dome Mountains in the south, this refuge is accessed by a network of graveled roads, most of which require four-wheel drive vehicles. However, the road to Palm Canyon, leading east from US 95 between Quartzite and Yuma, can be traversed by the family car and is perhaps the best means to explore this ecosystem; a short trail at its terminus leads to a stand of California fan palms and conditioned hikers can proceed on to higher terrain.

In addition to the fan p…

Southwest Storm

Yesterday morning, a deep atmospheric trough covered the western U.S., its leading edge stretching from southern New Mexico to Upper Michigan. As cold air poured southward within this dip in the jet stream, a powerful storm developed along its southern rim, sweeping moisture up from the Gulf of Mexico.

By later in the day, the storm had moved into the northern Texas Panhandle and its central pressure was falling. Strong, counterclockwise winds raked the Southern Plains and, northwest of the cold front, blizzard conditions developed across northeast New Mexico, southeastern Colorado and southwestern Kansas. Ahead of the front, Gulf moisture was streaming through the Midwest, igniting thunderstorms in northeast Texas and heavy rain across eastern Oklahoma, eastern Kansas and most of Missouri.

This morning, the storm has weakened and its center swirls over western Oklahoma. High pressure, dropping southward within the trough, has shut down the snowfall and has shoved most of the rain…

Selling the Church

Tuning into 60 Minutes last evening, I encountered the usual mix of TV commercials for cell phone services, stock brokerages, automobiles and erectile dysfunction medications. But a new ad appeared amidst those expected enticements and was clearly aimed at the upscale, sophisticated viewers of that respected, long-running program. This polished and obviously expensive ad (given its placement on 60 Minutes) was directed at fallen-away Catholics; with images of the Vatican and scenes of aid work across the globe, it was a clear effort to restore the tarnished image of a once powerful and influential institution.

Reeling from the ongoing child abuse scandal and faced with an increasingly educated and skeptical populace, the Catholic Church is attempting to invoke a sense of nostalgia with this advertisement campaign. Whether a Fifth Avenue approach will be effective remains to be seen; after all, it is directed at past members who are unlikely to respond to this glossy package, having…

A Sherbet Sunrise

Yesterday morning, as I left Denver under clear, cold skies, I was treated to a spectacular sunrise on the High Plains. The mellow but brilliant colors reminded me of the rainbow sherbet that I often enjoyed as a child (and still do on occasion). Low, flat clouds had taken on a raspberry glow while a swath of lemon yellow stretched across the horizon, fading to lime green at the fringes. As sunrise approached, the pale yellow evolved to a deep orange off to the southeast, marking the site where the sun would soon appear.

Humans have always been inspired by the sunrise and, for early man, it surely brought hope after the long, frigid winter nights. Even today, the sun's return is especially welcome after the extended periods of darkness that typify the season. More than signifying the recovery of light and heat (what little is provided by a low winter sun), the colorful display offers reassurance that nature's cycle will persevere.

Some may feel that I am overstating the s…

The Owens Valley

The Owens River of southeast California rises along the eastern flank of the Sierra Nevada Mountains, at the southeast edge of Yosemite National Park. After flowing eastward through the Long Valley Caldera, the river angles to the south-southeast and begins its journey through the magnificent landscape of the Owens Valley.

The Owens Valley is a geologic graben, a block of crust that dropped between the parallel faults of the Sierra batholith to its west and the White-Inyo fault block mountains to its east; as the mountains rose on either side, this block slipped downward. The floor of the valley has an elevation of 4000 to 3500 feet (north to south) while its steep walls rise toward some of the highest summits in the Lower 48; the latter include Mt. Whitney in the Sierra Nevada (14,498 feet) and White Mountain Peak (14,252 feet) in the White Mountains. The latter range also includes Boundary Peak (13,167 feet), the highest point in Nevada, while the Inyo Mountains, known for their …

The Art of Parenting

Ask responsible parents and you will find that they all agree on one point: Parenting is both the most rewarding and the most challenging endeavor that a human can undertake. More than a duty to provide food, clothing, shelter and education, it involves the commitment to guide a child (or children) through the varied, tumultuous stages of growth and maturation.

The art of parenting is the ability to offer advice without preaching, to instill confidence without stoking arrogance, to set boundaries without smothering creativity, to encourage social responsibility without stifling personal independence and to foster achievement without setting unreasonable goals. An engaged parent recognizes the innate abilities and natural talents in his or her child and makes the effort to provide the resources (financial, educational and social) that will facilitate their development. Above all else, good parenting involves the capacity to listen, the fortitude to discuss difficult issues and the w…

River Refuge

Following a period of exceptionally cold weather along the Colorado Front Range, most of our lakes and ponds have frozen over, sending waterfowl to the South Platte River for vital nourishment. This annual phenomenon, earlier than usual this winter, concentrates the varied species of waterfowl as well as their natural predators. For birders and naturalists, this seasonal river refuge offers an opportunity to see a wide variety of species on a relatively short hike.

Yesterday morning, under clearing skies and amidst the warming air of a gentle chinook, I took a walk along the river through South Platte Park, in Littleton. As expected, ducks were abundant, including mallards, gadwalls, green-winged teal, buffleheads, common goldeneyes, common mergansers and a few ruddy ducks; hooded mergansers were unusually common, including one flock of a dozen birds. Belted kingfishers, great blue herons, ring-billed gulls, Canada geese, killdeer, black-billed magpies and the usual mix of winter …

Front Range Geese

Lying at the western edge of the Central Flyway, the Front Range of Colorado has always been an important rest stop for migrating Canada geese. Before human habitation, the wetland corridors of the South Platte and Arkansas Rivers attracted these migrants on their journeys between Canadian breeding grounds and wintering areas to our south.

Irrigated croplands and man-made reservoirs were the first developments to alter this pattern, encouraging some of the migrants to settle in for the winter; after all, contrary to popular perception, winters are relatively mild along the Front Range, the product of abundant sunshine, dry air and frequent chinooks. As the human population of the urban corridor exploded over the past several decades, many more lakes, reservoirs, parks and golf courses have made the region even more appealing to Canada geese and some never bothered to return to their homeland. Today, it is estimated that 150,000 Canada geese are permanent residents of the Colorado …

The Wichita Mountains

Rising from the flat terrain of southern Oklahoma, northwest of Lawton, ridges of igneous and metamorphic rock trend northwest to southeast. Thirty miles long, these rock formations originated in a rift zone that developed from the late Precambrian Era into the Cambrian Period, some 550-600 million years ago. Though the rifting process was aborted, plutons of granite, intrusions of gabbro and deposits of rhyolite were encased within and atop the surrounding crust and, over the next 20 million years, were covered by layers of younger Paleozoic sediments.

During the Pennsylvanian Period, about 325 million years ago, the continents began to merge into Pangea. The collision of North America and Africa crumpled up the Southern Appalachians and the docking of South America extended that collision zone toward the west, lifting the Ouachita and Wichita Mountains. Erosion coincided with this uplift and continues today; having carried away the overlying and encasing sediments, wind and water…

December on the Plains

As I left Columbia this morning, a silver dollar moon beamed in the western sky, illuminating the predawn landscape. By the time I reached western Missouri, the pink rays of sunrise were reflecting from a deck of high, puffy clouds and several flocks of snow geese wavered southward above the rolling farmlands.

Once I entered Kansas a thick layer of clouds covered the sky but rusty grasses of the Flint Hills added color to an otherwise drab landscape. Numerous red-tailed hawks perched along the highway, restless Canada geese moved among the crop fields and a lone Cooper's hawk streaked across the roadway, headed for a valley woodland. The first snow banks appeared west of Hays and snow cover waxed and waned for the rest of my trip, peaking near Colby, Kansas, and along the base of the Front Range. On the High Plains, flocks of meadowlarks, horned larks and longspurs drifted across the fields, ring-necked pheasants foraged along the highway and northern harriers flapped low abov…

The Nomad in our Soul

Last evening, a flock of cedar waxwings moved across the slate blue sky, heading toward the orange glow of sunset. We birders are fond of waxwings, admiring their agreeable nature, their cooperative behavior, their attractive plumage and, in particular, the carefree independence of their nomadic lifestyle.

We humans, after all, were nomads for more than 90% of our history. Having evolved some 130,000 years ago, during a warm interglacial period of the Pleistocene, we roamed about sub-Saharan Africa for 50,000 years, trapped by a vast desert to our north and deep seas to our east, west and south. Then, as the Wisconsin Glaciers expanded, sea levels fell and the Sahara retreated, permitting our migration out of Africa that began about 80,000 years ago. By 60,000 YA we had reached Australia and by 50,000 YA humans were in Japan; our ancestors arrived in Europe 40,000 YA, in Siberia about 30,000 YA and had crossed into the Americas by 20,000 YA. Throughout all of this time, members o…

The Unexpected

In the course of our daily lives, unexpected events tend to be of the negative variety, producing hardship and disruption; accidents, injuries, acute illness, plumbing problems and other crises come to mind. Indeed, there are some periods in our lives when we seem to lurch from one crisis to another.

However, for those of us who enjoy the exploration of natural areas, unexpected events are usually rewarding and, in fact, motivate our desire to engage in such activity. Unexpected encounters with various species of wildlife or theretofore unseen plants instill memories that draw us back to the woods, fields and wetlands. It is the anticipation of such experiences that encourage naturalists to visit new areas, whether they are just across town or on the other side of the globe.

Over time, the unexpected may occur less frequently but the potential for its resurgence continues to feed our thirst for adventure. After all, the opportunity to experience nature's hidden and transient g…

Holla Bend NWR

In 1954, the U.S. Army Corps of Engineers straightened a section of the Arkansas River in an effort to reduce flooding in west-central Arkansas. This detour left an abandoned river bed that dips to the south and, since 1957, Holla Bend NWR has occupied the floodplain ecosystem that lies between the Arkansas and its old channel. Characterized by crop fields, wetlands, shallow lakes and bottomland woods, the refuge is known for its large number and variety of wintering waterfowl; in recent years, this has included trumpeter swans, brought from Iowa in an effort to re-establish a Midwest migratory population.

Attracted by the waterfowl, bald eagles also congregate at Holla Bend during the colder months, as do a number of golden eagles. Permanent residents include greater roadrunners, armadillos, coyotes and a large herd of white-tailed deer while a variety of herons, egrets, rails, shorebirds and summer songbirds inhabit the refuge during the warmer months. Least terns breed at Holla…

Swans over Columbia

At exactly 8:30 this morning, I glanced out a window at the University of Missouri Hospital, just in time to see a flock of swans. Moving east to west over the football stadium, they were too distant and my observation was too brief to make a species identification. Needless to say, the sighting was an unexpected shock to my system and they moved out of view before I could even get an accurate count; my guess is that a dozen swans comprised the flock.

Whether they were tundra or trumpeter swans is impossible for me to say but this was, by far, the largest congregation of swans that I have ever seen in central Missouri. Tundra swans, which breed across the Arctic, generally winter on estuaries along the Pacific and Atlantic coasts though some head south along the Rocky Mountain corridor to wetlands in New Mexico and Texas. Trumpeter swans breed on lakes throughout parts of the Northern Rockies and have been reintroduced across the Upper Midwest over the past few decades; most of th…

Lessons from the Silk Road

Established more than 2000 years ago, the Silk Road is the popular name for a network of trading routes that connected China with the Mediterranean region. These terrestrial roads and sea lanes facilitated an interchange of ideas, products, materials and food items, fueling the rise of early human civilizations and promoting the growth of large urban centers across Eurasia.

Yet, this vanguard of our modern global economy had negative effects as well. The routes were conduits for the spread of disease, the transport of slaves and the invasion of armies. In addition to the valuable goods, caravans and sailing ships brought political and religious zealots, spreading their message with a mix of promise and intimidation.

While modern technology has increased the speed and scope of global trade, the interaction of human cultures continues to produce benefits and risks. The natural tendencies of mankind, focused on personal welfare and survival, assures an imbalance of resources, an abus…

Humans & Cold Weather

Most humans, it is safe to say, are not fond of cold weather; we are, after all, tropical creatures, designed to function in a warm climate. While we enjoy an occasional snowstorm, relish the scent of wood smoke and look forward to the winter Holidays, the first taste of polar air triggers a longing for spring that often persists through the season.

Though we cannot shake our subconcious, genetic recoil to cold weather, some of our negative attitude is learned. Children, while naturally oblivious to threats that surround them and seemingly undaunted by the cold and snow, often learn to despise winter by observing and listening to the reaction of their parents. Then there is that human phase, from the teens through young adulthood, when attention to appearance outweighs the importance of appropriate winter clothing, instilling memories of cold exposure that persist through life.

For all of these reasons, many if not most humans come to loathe winter weather and prefer to remain indo…

Winter Sinks In

The dip in the jet stream that brought frigid temperatures, snow and Santa Ana winds to the West over the past few days has broadened out and the atmospheric trough now covers the western two-thirds of the country; this morning, its leading edge extends from south-central Texas to western New York and wintery conditions stretch from this front all the way back to the Pacific Coast.

A reinforcing cold front has also dropped southward through the Rockies, bringing single-digit and below-zero (F) temperatures to the northern parts of that region while low pressure over the Desert Southwest is spinning snow into southern Colorado, New Mexico and West Texas. Light snow is also expected along the southeast edge of the trough, including northeast Texas, northern Arkansas and southeast Missouri. Here in central Missouri, we dodged the precipitation but the temperature at dawn is 27 degrees F and highs are expected to remain in the thirties for the next several days.

Unlike many winter storm…

Darker Days, Brighter Nights

In the American Midwest, winter days are darker and, of course, shorter; sunrise begins later and sunset occurs much too soon. While sunny days come along, most are cloudy and the low sun angle provides little heat. It is, indeed, a gray and daunting season.

On the other hand, winter nights are often ablaze with stars. The dry, frigid air, free of summer haze, provides an unfiltered view of the heavens, a dazzling display of light arriving from the distant past. Though our own sun has retreated to the south, thousands glow overhead, lending perspective to our lives here on Earth.

The depth of our winter darkness is less than three weeks away but solar warming will take much longer to recover. Until then, we can gaze at distant suns, knowing that they are bringing summer heat to countless populations across our vast Universe.

Short-tailed Weasels

Short-tailed weasels, also known as ermine or stoats, are circumboreal in their distribution; in North America, they are found across Alaska and Canada, extending southward to the Northern Sierra, through the higher Rockies to New Mexico, across the Upper Great Lakes region and into New England. These small mustelids favor taiga, stunted timberline forest and open, brushy woodlands along streams; there they hunt for voles, mice, pikas, chipmunks, rabbits and small birds.

Solitary for much of the year, short-tailed weasels mate in summer and, after a period of delayed implantation, an average of 6-8 kits are born the following spring; able to fend for themselves within 2 months, the young disperse by late summer. Adult short-tailed weasels are generally 10-12 inches long and sport a brownish coat with white underparts during the spring and summer months; come fall, they molt to a white pelt to blend with their snowy surroundings though the tip of their tail remains black in all seas…

Evolution & Climate Change

Most life forms, including the first unicellular organisms, evolved in tropical ecosystems. Even today, the Tropics harbor the great majority of species on Earth and provide an environment in which new species are most likely to evolve.

Over the eons, adaptation to a temperate or cold climate fostered more diversity as plants and animals dispersed across the planet, continents drifted toward colder latitudes and Earth's climate gyrated between periods of glaciation and global warming. Physical traits such as feathers, fur and fat insulation favored survival in the cold while some species developed behavioral adaptations such as migration, estivation or hibernation to survive in regions with a dramatic change in seasonal conditions.

We humans also evolved in the Tropics but, thanks to our large brains, were able to adapt quickly to colder climates without "waiting" for natural selection to control our expansion; the capacity to utilize fire, produce clothing and constr…

Ripples in the Sky

Last evening, after two days of clear, cold weather, a shelf of high clouds stretched across the western horizon, lit by the colorful rays of the setting sun. Along the leading edge of this sheet of ice crystals was a series of ripples, giving the appearance of pink beach sand, molded by incoming waves.

This spectacle was produced by low pressure over the Great Plains, injecting moisture into the upper layers of the atmosphere and creating turbulence as the rising, warmer air encountered the frigid air at an altitude of 40,000 feet. Later in the evening, this thin veil of cirrus clouds moved across central Missouri and produced a halo around the bright crescent moon.

Such high cloud formations usually signal an advancing front and, in this case, a deep trough is forming across the western U.S.; this dip in the jet stream will bring heavy snow and frigid temperatures across the Rocky Mountain corridor and spawn Santa Ana winds in Southern California. Ahead of the front, milder air i…