Outside of Florida and the extreme south of Texas, few places in the conterminous United States see temperatures regularly reach the mid 80s in the dead of winter. While it is nice having warm, clear weather in January, the California sunshine that fuels this weather is a double-edged sword for the Golden State. For it is in winter when most of the state’s precipitation falls. This is a crucial time for replenishing the state’s water resources and nourishing it endemic flora and with life-giving water.

Coastal southern California is not technically a desert climate, at least not yet. Many climatologists draw a line separating true deserts and semi-arid environments at 10″ (254 mm) of precipitation per annum. Most of southern California is well above this threshold. Downtown Los Angeles, for instance, normally receives just under 15″ (381mm) of precipitation in an average year. But rainfall is well below average again this year throughout most of The Southland. Only 1.22 inches (30.988 mm) have been measured this season at a station in Thousand Oaks — near where these pictures were taken. The normal tally to date for that location would be 6.39″ (162.3 mm). So in this location, at least, conditions are only at 20 percent of “normal.”

It is important to understand that the lower the total precipitation average is in an area, the higher the precipitation variability will be from year to year in that location as well. Yet there are other factors that are helping to push California into drought conditions. The warm and dry weather of the past few days has been the result of a moderate Santa Ana condition. High pressure parked to the east in the high deserts of the Mojave and Basin and Range provinces provide the impetus. A pressure gradient soon results which then funnels clear, dry air towards the relatively lower pressure near the coast. In transit, the moving air heats by compression and picks up speed as it descends toward the ocean. In turn, this offshore flow usually brings warm temps, dry conditions and keeps the marine layer at bay in places like Santa Monica — which will often experience warmest temperatures and clearest skies of the year during such events.

Our daily weather is influenced by longer term events in the climate. Currently we have La Niña conditions that are strengthening and helping to give rise to the warm, clear and sometimes windy weather that we have seen over the past month. La Niña is the lesser known sibling of El Niño. Together these two phases in the Pacific Ocean Basin make up what is called the El Niño-Southern Oscillation or ENSO. These patterns shift every few years and the conditions they produce can last several months to several several years, depending on factors that are still being discerned. Generally speaking, the El Niño phase shifts circulation patterns so that warmer than normal ocean water at the surface flows to the eastern Pacific. For California this often means more winter storms and the rains that accompany them. La Niña is a reversal of this phase. Colder than normal water piles up in the eastern Pacific, which often leaves California high and dry in the winter months when the bulk of the state’s nourishing rains and snow falls.

So what does this all mean? No one can say with absolute certainty. The discovery of ENSO was only flushed out about 100 years ago. Consensus on climate change only began to crystalize in the 1980s. But some reasoned inferences can be made. Data continues to pile up supporting the postulation that the Earth’s climate is not only warming but becoming more variable and, to a certain degree, more unpredictable as well. However, it would be a mistake to think this is all guess work. Climate scientists now have conclusive evidence: the coming changes will mean wilder swings in drought and deluge for much of the planet, including the Golden State. Only the extent and duration remain unknown.

California sunshine is legendary and has attracted immigrants and adventurers for centuries. But that might not always continue to be the case. In the era of climate change, that omnipresent sunshine may begin to drive the same such folk to more habitable climes in the future.

The post All The Hills Are Brown and The Sky Is Blue … first appeared on Rediscovering the Golden State.

Our weather science story begins when summer turns to autumn. Land masses in the Basin and Range and Desert Southwest begin cooling much faster than the ocean surface. Summer’s less dense, expanding air masses in the thermal low pressure that has dominated over land are replaced with cooler, denser, sinking air masses in the Basin and Range during many fall and winter days and especially colder nights. The thermal low that was sucking in summer’s sea breezes from the coast is replaced by the cooler Great Basin High surface pressure that forms in this frigid air of fall and winter. As heavy, dense air settles out of this high pressure system, the wind flows away from the high and toward now relatively low pressure near the coast. The Coriolis effect spins this land breeze a little to its right as it flows over California. These cooler air masses are forced to compress and squeeze through California’s mountain passes and canyons on their way toward sea level and the coast. This compression heats an already dry continental air mass as it cascades into inland and coastal valleys on the ocean sides of the mountains. Relative humidities can drop well below 10%.           

Whether you call them Santa Ana (southern California) or Diablo (northern California) winds, they announce fall’s arrival. Each year, we witness a competition that will determine the severity of our state’s fire season. Will the first weather fronts drop down from the Pacific to bring quenching rains to a state parched by several months of summer drought? Or will the dry winds come first, blowing across fire-adapted pant communities and baked soils that haven’t yet received the season’s first showers? Every year is different. In the fall of 2017 and 2018, brutal winds arrived before the rains, following especially long, hot, dry summers. Relative humidities dropped below 10% in the compressionally heated winds that fanned epic firestorms of death and destruction.

The accompanying weather maps (thanks again to NOAA’s National Weather Service) display some specifics from the most deadly days of November 2018. The surface map shows a steep pressure gradient from inland to the coast. And this event had the upper atmosphere support that is so important in bolstering the offshore winds so that they howl throughout the day and night. Note the 500mb map that shows air pressure and wind flow patterns approximately half way up through our atmosphere, around 18,000 feet (5,600 meters). Here, you see a large ridge of high pressure over the eastern Pacific that extends above the California coast. This shows upper level support that encourages a stronger offshore flow. Upper level winds will blow roughly parallel to the lines on this isoheight map (this map showing the height of 500mb) as those meandering winds flow west to east around the globe. You might be familiar with the upper level jet stream that can be embedded within these air flow patterns.

Just as these upper level winds curve up toward the north and over the ridge, they then meander back down south, toward the adjacent trough. This upper level motion causes the stream of air to slow down and become denser and heavier just east of the ridge, similar to how traffic on the freeway slows and bunches up behind various obstructions. Here is where negative vorticity advection and anticyclonic flow usually dominates. This denser air sinks, fortifying high pressure at the surface. It’s the combination of this upper level support on top of the already cold, dense high pressure at the surface that creates the strongest offshore winds. Winds blow out of this strong surface high pressure and toward lower pressure near the coast or out into the ocean. The Coriolis effect pulls the winds slightly to their right, spinning the air clockwise out of the high, resulting in strong surface winds that may gradually shift from north to northeast to east over days as the high pressure slowly migrates farther east. Eventually, the pressure gradients ease as the pressure cells change and migrate; the offshore event ends.

The good news is the fires are contained in the relative calm aftermath. The bad news may be displayed in layers of residual smothering smoke that hover over and downwind of the fires in the stable air. This air quality problem that takes us full circle to the start of our fire essays earns one more lesson in weather science. After the high pressure responsible for these offshore winds weakens and/or moves east, normally migrating northern hemisphere pressure systems and their shifting winds often disperse the smoke and may even deliver precious moisture to parched landscapes as winter’s storms begin to drop south and clear the air. In other cases, the weather patterns may briefly stall, leaving a stable, stagnant atmosphere lacking the winds necessary to disperse smoke from the fires.

The later was the case on November 10, 2018, the day after the Woolsey Fire erupted in southern California as the L.A. Basin was shrouded in orange and red. Dangerous air quality was measured until another Santa Ana event scoured out the basin on the next day.  Still, one week after the Paradise Fire erupted and was being successfully contained, a veil of toxic smoke from that blaze had covered the Sacramento Valley and drifted all the way over the Bay Area. Schools were closed, athletic events were canceled, and officials discouraged any outdoor activities from the Sacramento Valley through the Bay Area. Even The City’s iconic cable cars were shut down. 

How bad was it? We can start with the gone-viral photo taken by editor David Little and published by the Chico Enterprise Record just as the Camp Fire was spreading terror and death. As the winds gradually subsided, so did the air masses, allowing the accumulating smoke clouds to creep across the Sacramento Valley until they were finally strangling the Bay Area. Six days after the Camp Fire started, air quality was still some of the worst ever recorded in the region, the accumulated smoke capped by a ridge of high pressure overhead. More than 35 micrograms of small particulate matter per cubic meter are considered unhealthful by federal standards. But monitors around Chico and Gridley were recording more than 300 micrograms and one temporary station between Chico and Paradise recorded dangerous amounts over 900 micrograms per cubic meter. These microscopic particles of ash can lodge deep within the lungs, causing serious health problems.   

So these latest nightmares started with the dreaded National Weather Service wind advisories and red flag warnings for November 9, 2018 that turned out to be spot on. They included those NWS warning maps covering an area from the coastal ranges across the Central Valley and well into the Sierra Nevada foothills. At the same time, another NWS map displayed high wind or red flag warnings for all southern California mountains and coastal valleys. As was feared, apocalyptic firestorms swept through both regions. One week later, the maps forecast the dangerous air quality that spread into the Bay Area as responders dug through the ashes in Paradise hoping not to find the remains of hundreds of people still missing. Luckily, most were finally found alive, except for the 85 victims who perished. Our mission and responsibilities couldn’t be clearer or more urgent: our efforts to better understand the forces of nature and our interactions with them, and our abilities to anticipate what comes next require our immediate attention.       

The National Weather Service is the original source of all weather forecasting information in the United States.

The post Weather Science Behind the Firestorms first appeared on Rediscovering the Golden State.

On Saturday, November 10, 2018, people in many parts of northern and southern California woke up to another eerie orange and red smoky sky that had become all too common, the choking residue from the latest most destructive and deadly wildfires in our state’s history. Most of the larger ashes remaining from so many California dreams had already fallen out of what were once such well-defined towering pyrocumulus (flammagenitus) clouds.

Smoke from the deadly Camp Fire in Sierra Nevada foothill country eventually spread across the Sacramento Valley and later into the Bay Area. Smoke from the Hill and Woolsey Fires in southern California first blew out over the ocean and then gradually mixed into the atmosphere. When the offshore winds eased and turned gently onshore the next day, the clouds had diffused into veils of stifling smoky haze that would decorate sunrises and sunsets red as they drifted onshore, discouraging physical excursion for the next few days, and punishing millions with respiratory ailments. It was as if we were again witnessing the hangovers from what many viewed as nature’s latest tantrums, as she leaves behind the bodies of those who couldn’t escape the flames on foot or in their cars. But nature’s latest way of reminding us who is really in charge was also a reminder that we must better understand the science behind these events and we must also be more careful and thoughtful about where and how we choose to live.  

Some of us natives are old enough to remember how these occasional infernos played out every fall, and more recently during other times of year, more evidence that fire seasons have expanded in area, severity, and time. We examine the science and human factors that help explain and contribute to these catastrophes in our publication. Here, we will focus on the factors that combined to produce these latest disasters that make 2018 the latest in this string of worst wildfire years in the state’s history. It turns out that these firestorms that scorched through iconic neighborhoods in southern California and literally destroyed Paradise in northern California have become more common for several reasons.

Let’s begin by understanding what is NOT primarily to blame for most of these recent infernos. A few clueless demagogues have suggested the state has allowed some mysteriously magical source of accessible firefighting water to flow into the ocean. Our project’s analysis of California water resources and geography proves why they have failed their lessons in hydrology and water policy before they even started. Other opportunist politicians and the echo chambers following them have suggested that California is to blame for allowing tree densities to increase in our forests. They have even threatened to cut off our funding to punish us for these “mistakes”. But a rational analysis of the facts doesn’t support such shamelessly uniformed anti-California hysteria.  

First, the vast majority of the state’s most deadly and destructive wildfires in the last several years have started and burned in chaparral, coastal sage, and woodlands, NOT in forests with dense trees. You could cut down every tree in every California forest and most of these deadly fires would still have raged. You’d have to bulldoze and pave all the other plant communities that cover the majority of the state if you want to end these fires.  

Second, the majority of California forests that do exist are on federal lands, meaning that the very outside politicians blaming California are in charge of the very forest management they blame for the disasters. And those already underfunded forest management programs have been suffering from past budget cuts championed by those same feds. History haunts us here. More than a century of snuffing out all fires that started in our National Forests and parklands finally ended in the 1970s when forest managers realized that occasional beneficial fires cleared dangerous fuel that would otherwise accumulate to cause more intense, devastating, and out-of-control catastrophes. We were stuck with the fuel from poorly informed policies of the past. Control burns have become a vital part of forest and woodlands management in California ever since the 1970s, lessons we could have learned from Native Americans who practiced this for centuries before we managed these lands.  

More recently, after more than 100 million trees died from drought and bark beetle infestations in the Sierra Nevada, it is estimated that about half of all California forests are in serious trouble. In response, California has doubled the acreage open to vegetation thinning, and the U.S. Congress has finally stopped cutting programs that could save billions in losses and instead has restarted funding for sound forest management in the state. Many local communities have thinned their forests and required defensible spaces around structures. Appalling and repeated losses of life and property remind us that short-term investments in sustainable forest management will result in saving lives and a lot of money in the long term.             

Now that we see how we are tackling just one of the perceived problems, what is really to blame for these historic conflagrations? First and most obvious is climate change. Those bark beetle infestations are directly linked to some of the longest and most severe droughts and heat waves in recorded history. Additionally, forest managers have demonstrated that several inches of rain may be required to replace evapotranspiration losses from just one degree of warming above the historic average in places like Sierra Nevada foothill country. And average California temperatures have increased roughly the same as global temperatures over the last century, more than 1.5 degrees F.

The 2017 and 2018 fire years also illustrate the importance of those first rains of fall (as the jet stream and storm tracks commonly migrate south) to douse what would otherwise be critical fire conditions each year in northern California so that fire responders can focus on the often still dry southern California and its Santa Ana winds. In the 2017 season, the storms arrived late in northern California, following one of the hottest and driest summers on record, and it happened again during the even drier autumn of 2018. This left an abundance of exceptionally dry fuels waiting like open buffets for the autumn winds that whipped flames into a feasting frenzy. Exhausted fire crews were fighting in northern California as southern California’s fires, as anticipated, erupted amid the annual Santa Anas.            

Though researchers emphasize how dehydrated introduced non-native invasive species (such as cheatgrass) serve as added conduits to spread fires, these growing threats earn little attention in the media. Throw increasing populations into these fire-prone plant communities and it is easier to understand this recipe for disaster that has repeatedly broiled into death and destruction from north to south. More recently, we have seen how PG&E and SCE are facing crippling liabilities as their aging power infrastructures fail and throw sparks into the fuels parched by these relentless, unprecedented weather patterns. Arson, target shooting, landscaping work, careless smokers and campfire enthusiasts, and sparks and heat from vehicles round out some of the other sources for fire starts. You can see why lightning no longer leads the list of culprits.

Solving California's Firestorms

Here, western potions of the Santa Monica Mountains were recovering from another fire just a few years before the 2018 Woolsey Fire would burn some of the same landscapes.

Fuel for the Fires

Fuel for the Fires

Smoke on High

Drought and Bark Beetles

Ready to Burn

Destroying Paradise

Pyrocumulus (flammagenitus) Cloud

The post Solving the Historic California Firestorms Puzzle first appeared on Rediscovering the Golden State.

In southern California two fires are menacing the Conejo Valley and Thousand Oaks, the community that was just rocked by a horrific mass shooting on Wednesday night that claimed the lives of 12 victims along with that of the gunman. 

The Woosley Fire started on Thursday and as of Friday has burned more than 10,000 acres in the Simi Hills and Santa Monica Mountains that straddle Los Angeles and Ventura Counties.  Some 75,000 homes are under evacuation orders in the two counties. 

Emergency and Evacuation Information

Strong Santa Ana winds allowed the fire to leap the 101 freeway and the blaze is now threatening the communities of Agoura Hills, Calabasas, Malibu, Oak Park, Simi Valley,  Thousand Oaks and Westlake Village.  

Just a few miles west, the Hill Fire also ignited Thursday afternoon and rapidly grew to over 6,000 acres. This fire arose in the Hill Canyon area between Thousand Oaks and the Santa Rosa Valley. It has now spread to adjacent areas of Camarillo, Newbury Park and threatens the western Santa Monica Mountains as well. 

Meanwhile in northern California the Camp Fire has charred some 70,000 acres in Butte County as of Friday and was only 5% contained.  The fire incinerated parts of Paradise and was threatening Chico this morning.  Some 40,000 residents have been ordered to evacuate.  It is estimated that at least 1,000 buildings  have been destroyed so far.  Many injuries to residents and firefighters have been reported. 

If you are in or near any of the areas affected by these fires please keep tuned to updates by emergency personnel and heed all instructions to evacuate if ordered or asked to do so. 

These are developing stories and we will provide updates as more information becomes available. 

The post Several Wildfires Erupt Across the Golden State first appeared on Rediscovering the Golden State.

But the fires that terrorized neighborhoods in Northern California two months ago were different. They happened in an area that was previously thought to be relatively safe and distant from parched wildlands prone to burning. This was the case in the calamitous firestorms that developed in October 2017 north of the Bay Area. Epic torrential winter rains had just doused a relentless, historic drought. This was immediately followed by a record hot and dry summer in northern California, leaving a mélange of overgrown grasses to mix with open and dense woodlands, a parched recipe of fuel waiting for nature’s next surprise.

Late one Sunday night, autumn’s dry offshore “Diablo” winds cascaded down Coastal Range mountain slopes with up to 70 mph gusts, stronger than locals said they had ever experienced that time of year, downing trees and live power lines that may have sparked the nightmare that followed. The gusts were heated by compression and quickly drove racing walls of flames directly through the dried woodlands and grasses and into neighborhoods in places like northern Santa Rosa and parcels scattered throughout the state’s storied Wine Country.

Entire neighborhoods and wineries were burned to the ground in firestorms so fast and violent that hundreds of terrified families were forced to run for their lives in that one night. Within one week, thousands had been forced to evacuate as more than 8,000 homes and business were destroyed, including entire stores and shopping centers. The more than 40 people killed in the destruction that totaled several billion dollars made this the most deadly wildfire in California history.

Such tragic events have long been anticipated and even experienced in communities near southern California’s mountain slopes and wildlands during Santa Ana winds (such as in San Diego County earlier in the century), but they have become ominously more frequent in these northern California communities during recent years.   

In our book, we examine the natural forces and cycles and the human decisions and developments that combine to create these firestorm catastrophes. But we cannot forget the human tragedies and suffering left behind and the geographic dangers that are sometimes part of life in California’s suburbs and exurbs that might encroach into natural landscapes.

You could feel a sense of loss by reviewing some of the comments that were made on social media before and after the fire that burned the community of Coffey Park to the ground on that Sunday night. Their park was a beloved resource to this neighborhood that seemed to disappear in minutes. Here are a few excerpts from that will help us make these connections to the geography and the people living there.

Forty reviews rated their park 4.3 out of 5 before the firestorm. They included:

“Nice place for a Sunday afternoon walk”

“Small but nice neighborhood park serving the houses around it.”

“It is a nice park for people of all ages.”

“Walking distance from my house. Grandkids love the park.”

“I live in the neighborhood, and this is a great local park. 2 play structures and a large field well suited for soccer or football games. All the benches have charcoal grills, so it’s also a good place for birthdays and BBQs.”

“Best park in S.R.”

“Been at this park since my first born…we now visit every summer and still come by here and spend the whole afternoon walking/running while the kids play at the slides & swings”.

After the fire, the messages turned heartbreaking: 

“Not anymore! Fire got it all destroyed!!! 

“Sadly, the entire surrounding area has been destroyed in a wildfire.”

Already by October 12, 2017, the Google reviews page started with “Permanently closed”. And by November 27, one message read:

“Moving day: As we sifted together through the rubble that once was their beloved home, it started to sink in…there isn’t much left to find. The fire tornado that burned though Coffee Park was so quick and hot that almost everything the fire touched turned to ash. Moving on is not easy, but it is the only path going forward…”

UPDATES: In our publication, we reported that the deadliest (wine country) and largest (Thomas) wildfires in California history occurred in 2017. Unfortunately, we had to report that the Mendocino Complex fire, at more than 450,000 acres, set the new record as the largest, at least by September 2018. Though the Mendocino Complex was actually two fires (the Ranch and River fires) that burned through four counties, most of the acreage burned in the Ranch fire, which would have been the largest alone. The fires started in July and were finally contained by September, as California’s 2018 fire season was running ahead of the record-setting 2017 season. We had hoped another update would not be required. Unfortunately, 2020 became, by far, the worst fire season ever recorded in California history. Look ahead on this web site to California Burning to find a separate story about the weather patterns that led to this latest most horrific fire year.

The post Deadly Firestorms That Ravaged Santa Rosa and California’s Wine Country first appeared on Rediscovering the Golden State.