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The Real Story Behind the California Wildfires

October 19, 2017

By Paul Homewood


Meteorologist Cliff Mass has the real story behind the recent tragic wildfires in Northern California:


There has been a huge amount of media coverage regarding the tragic northern California fires, documenting the terrible loss of life and billions of dollars of damage to buildings, infrastructure, and the economy.  As I write this, the death toll has risen to 41, over 5000 buildings have been destroyed or damaged, and the estimates of the financial loss are in the tens of billions of dollars.



Media stories have blamed the catastrophic fires on many things:  a dry environment after the typical summer drought, unusual warmth the past several months, excessive rainfall producing lots of flammable grass, strong winds, global warming, and  the lack of vegetative maintenance (clearing of the power lineright-of-ways) by the local utility (PG&E).


But none of the stories I have read get at what I believe is the real truth behind this unprecedented, severe, and explosively developing wildfire event:
A unique mountain-wave windstorm produced the strongest winds in the historical record at some locations.  An event produced by the unlucky development of just the right flow regime that interacted with regional mountains to produce extreme winds beyond contemporary experience.
In short, this blog will make the case that the extreme nature of the wildfires were the result of a very unusual weather event, one that our weather models had the ability to forecast and warn about, if only their output were applied more effectively.  The blog also suggests that better use of state-of-the-art weather prediction offers the hope of preventing a similar tragedy.

The Unique Wind Event
Although there have been a lot of media reports about windy conditions, few have described the extreme, often unprecedented, nature of the winds on Sunday night and Monday morning (October 8/9th).   Some have even mocked PG&Es claims of hurricane-force winds, suggesting wind speeds of 30-40 mph.

Let’s clarify a few things.  There was a wide range of winds that night, with the strongest winds on ridge tops and on the upper lee slopes of terrain.  Some winds was startling.
For example, at 10:30 PM on 9 Oct 2017 the wind gusted to 96 mph on a 3400 foot peak NE of Geyersville, about 20 miles NNW of downtown Santa Rosa. They reported sustained 74 knots (85 mph).  Those are hurricane force winds (sustained of 64 knots or more).
At the Santa Rosa RAWS station (U.S Forest Service and Bureau of Land Management) at 576 ft elevation, the wind accelerated rapidly Sunday night to 68 mph (see below).

What is really amazing about the winds at these sites, was that they were unprecedented:  the strongest winds on record, with records going back to 1991 (Santa Rosa) or 1993 (Hawkeye).  And we are not talking about winds during the fall, but winds any time during the year.  Even during the stormy winter season when powerful storms can cross the region.
At low-levels, the situation was more mixed.  For example, at Napa Valley Airport (36 ft), the sustained winds at 11:15 PM October 9 (37 knots) were the strongest observed (looking back to 2001) at that location from July 1- November 30, while at the Santa Rosa Airport (KSTS) the sustained winds only reached 28 mph, with 40 mph gusts.
So why were the winds so strong and unprecedented at higher levels in the hills?  These winds were key for causing the wildfires to explode and to quickly move into populated regions.  And the winds undoubtedly damaged power transmission lines and thus helped start electrical fires, which may, in fact, have initiated the big wildfire runs.  And why were the lower-level winds less severe?  What can explain such differences?

Read the full story here.


It is worth reiterating straight away that when he talks about “unprecedented”, he is only looking at records going back to 1991.

And, indeed, there was a remarkably similar wildfire in the same area in 1964, known as the Hanly Fire.

The Press Democrat published an article about this in 2013:


Black streaks run 40 feet up the trunks of a ring of redwoods in the Pepperwood Preserve off Porter Creek Road in the Mayacmas Mountains northeast of Santa Rosa.

The trees are healthy, silently bearing the scars of the epic wildfire of September 1964 that rattled Santa Rosa’s nerves before it was stopped about 100 feet from the door of the old Community Hospital on Chanate Road.

Nearly all of the 3,200-acre preserve was scorched as 70 mph winds, close to hurricane strength, blasted the Hanly fire from Calistoga through Knights Valley, Franz Valley and down the Mark West Canyon to what was then the northeast outskirts of Santa Rosa.

At 52,700 acres, the Hanly fire is the largest in Sonoma County — and fourth-largest in the Redwood Empire — in the last half-century.

It pales in comparison to California’s mega-fires, including the 255,560-acre Rim Fire still burning in and around Yosemite National Park, now the state’s third-largest wildfire since the 1930s.

Firefighters and forest ecologists say it’s unlikely the Redwood Empire will ever see such massive blazes, but destructive wildfires regularly erupt in the region, as they do all over the state.

The Hanly fire, ignited when a deer hunter tossed a cigarette into dry grass on the slope of Mount St. Helena in Napa County, remains as testimony to what happens when California’s recreation-friendly Mediterranean climate bakes grass, brush and trees dry every summer.

"All it needs is an ignition source," said Michael Gillogly, the Pepperwood Preserve manager, standing on an east-facing slope that the Hanly fire’s flames raced up 49 years ago. "It could burn any time."

Firefighters and forest ecologists agree: About 4,400 wildfires a year, covering nearly 220,000 acres, according to a recent five-year average reported by Cal Fire, are part of the circle of life and death in California.

"Fire is another of those processes built into the landscape," said Rick Mowery, a Mendocino National Forest fire ecologist. "A lot of California relies on fire to function in a healthy way."

Over thousands of years, the state’s flora and fauna have adjusted to fire, Mowery said. Species that couldn’t tolerate it "were gone long ago."

Nobcone pines can’t propagate without fire, while Ponderosa pines and redwoods are cloaked in thick bark that insulates them from all but the hottest fires.


The big difference between then and now is that many more people live in places like Santa Rosa. According to Wikipedia, the population there has exploded from 31000 in 1960, to an estimated 175000 now.

And Wikipedia also has this account of the Hanly Fire, and how it compares with the recent Tubbs one:

In 1964, the Hanly Fire, the largest fire in Sonoma County history, burned 52,700 acres, with striking similarities to the Tubbs Fire. Since 1964, hundreds of expensive homes, a golf course and clubhouse restaurant, office and medical buildings, light industry, lakeside retirement homes, a long row of nursing facilities, and two hotels were built in the Fountaingrove area, which had been almost entirely open land in 1964.

The path the Hanly Fire took in 1964, as well as the areas it burned, were very similar to the Tubbs Fire: from Calistoga, along Porter Creek and Mark West Springs roads into Sonoma County, burning homes along Mark West Springs and Riebli roads, through Wikiup, and to Mendocino Avenue, where it stopped, across the street from Journey’s End Trailer Park. The fire was propelled by 70 mph winds, close to hurricane strength, moving from Calistoga to Santa Rosa in only about half a day, but it only burned a few dozen homes.

Sonoma County has four "historic wildfire corridors," including the Hanly Fire area. New homes in the fire zones must meet building code requirements for fire-resistant materials for siding, roofing and decks, with protected eaves to keep out windblown embers. But despite a 100-foot fire break that ringed much of the Fountaingrove II subdivision, 600 upscale homes in the same path as the Hanly Fire, virtually the entire subdivision was destroyed by the Tubbs Fire.


I’ll leave the final comments to the experts who know about these things, from that Press Democrat report:


About 3,500 buildings, including homes for 9,600 people, a school, a PG&E substation and high-tech commercial buildings now occupy the area covered by the Hanly Fire and Nunn’s Canyon Fire in Sonoma Valley. Both started on Sept. 21, 1964 and together burned 65,800 acres and more than 100 homes.

Should the twin fires happen again, the damage to buildings and farms could exceed $1 billion and the firefighting costs would run into the millions, according to a scenario contained in the Sonoma County Hazard Mitigation Plan of 2011.

Current firefighting techniques might curtail the two fires, the scenario suggests, and Hoffmann noted that numerous vineyards now in the Hanly Fire’s path might slow down a blaze over the same terrain today.

But with a strong northeast wind, the phenomenon that drives the area’s worst wildfires, "all bets are off" he said.

Fire fuels quickly recover in burned-over areas. Dry grass can ignite every year; dead and downed forest litter accumulates in six or seven years; brush rebounds in about 20 years.

"California is made to burn," said Marshall Turbeville, a Cal Fire battalion chief based in Sonoma County.

About 33,900 people who live outside the county’s cities — representing 7 percent of the total population — are in areas "potentially at risk of wildland fires," the hazard mitigation plan says.

There are about 12,600 buildings in areas with "high and very high risk of wildfires," with an estimated replacement value of $4.8 billion, the plan says.

The county has four "historic wildfire corridors," including the Hanly Fire area, Sonoma Valley (scene of the Cavedale fires in 1925 and 1966), the Geysers (with fires in 1988, 1999 and 2004 that covered a total of 22,000 acres) and the Guerneville area (hit by major fires in 1923 and 1961, the latter burning 5,800 acres, 18 homes and $500,000 worth of timber.

In Santa Rosa, about one-fourth of the city’s residents live within four moderate, high and very high severity fire zones, mostly hilly, wooded areas all east of Highway 101.

  1. richard permalink
    October 19, 2017 1:07 pm

    Spread of non- native cheat grass is increasing wild fire across the US.

    • Gerry, England permalink
      October 19, 2017 2:16 pm

      Portugal planted lots of eucalyptus tress and wonder why they have bad fires.

  2. Broadlands permalink
    October 19, 2017 2:00 pm

    Santa Rosa…”the population there has exploded from 31000 in 1960, to an estimated 175000 now.”

    There is a high correlation between population and wildfires even though many are started by natural causes… lightning. Some are deliberate (arson), some are accidental, cigarette? But, more people will necessarily add to the probability?

    • Joe Public permalink
      October 19, 2017 2:12 pm

      “But, more people will necessarily add to the probability?”

      It seems it would in Europe, and behaviour can’t be substantially different that side of the pond:

  3. Russ Wood permalink
    October 19, 2017 2:25 pm

    Why isn’t the state taxing fire in order to control it? After all, this IS California!

  4. October 19, 2017 3:14 pm

    What the report doesn’t say, although it hints at it, is that the forests are not managed properly. The underbrush should be allowed to burn off regularly. This prevents high temperatures damaging the mature trees. Once the underbrush becomes sufficiently dense, it will ignite to produce temperatures which then cause unmanageable fires. With so many people now living in the forested areas, small fires that would burn off the underbrush are quickly dealt with and so the remainder continues to grow.

    In Portugal they have a somewhat different problem in that the forests are privately owned and individually are quite small. Historically, these have been properly managed, but in recent times the forests have been passed on the children who are not interested in managing them. Add to this the fact that they flout the Portuguese law that says that you must not plant trees within 50 metres of a road or track, thus reducing any firebreak possibility, and you have what has happened this year. Spain has the same problem as California of mismanagement or lack of management. In this communidad (Valencia) they have just reduced the number of firefighters and manned lookout towers.

    Forests are perfectly happy when they are left to manage themselves; as always, the problem is misguided human intervention.

    • Curious George permalink
      October 19, 2017 3:39 pm

      Most of affected areas are private lands. Local regulations might affect landowner’s forest management options.

  5. October 19, 2017 3:29 pm

    The fact that indigenous tree species such as the Californian Redwood have evolved in such a way as to require burning events in order to propagate should tell us that forest fires have been occurring in California for a very long time indeed.

  6. October 19, 2017 3:30 pm

    Reblogged this on Climate Collections.

  7. Ross King permalink
    October 19, 2017 3:42 pm

    A term used around W.Canada is “Fire-Ladders”, meaning an accumulation of dry undergrowth below the canopy, which facilitates a forest-floor-level fire to “climb the ladder”, ignite the canopy, and tree-hopping conflagration, driven by any wind. I am given to understand that the indigenous forest -dwellers clearly understood this risk, and “managed” the under-storey accumulation of flammable materials within a certain distance of their habitations. I think they might well have “managed” it by controlled burns in suitable weather.
    Any comments appreciated.

  8. Tim Spence permalink
    October 19, 2017 4:14 pm

    There might be an even bigger story here. After examining a lot of images of the fire, there are entire blocks of housing destroyed while 80% of the trees were untouched. The blazes seemed to go from house to house, not tree to house to tree. Granted, there are some images of forest fires but the images from the housing estates are uncanny.

    • John F. Hultquist permalink
      October 20, 2017 12:57 am

      Radiant heat from a hot wildfire can ignite curtains inside a house through large glass windows. Resistant shutters for windows can help.

    • GlobalMF permalink
      October 21, 2017 9:16 pm

      I noticed the same thing. What else can be expected when houses are built 10′ from each other, as those appear to have been? I have no idea what the roofs were made of on those houses, but I saw no metal roofing amidst the ashes. Seems like that would be a good first step to preventing those type of conflagrations that probably start on the roof tops, and then spread from house to house.

      • October 22, 2017 10:14 am

        …or better still, don’t allow houses to be built within the forests.

  9. MrGrimNasty permalink
    October 19, 2017 6:20 pm

    I thought I read somewhere that the governors had ignored a report stating that the archaic electricity distribution network was an imminent risk of causing wildfires in urban areas and mass casualties would result.

    Which seems to be exactly what has happened.

    If someone can find the link/story again (I’ve lost it) I’d be grateful.

  10. John Cooknell permalink
    October 19, 2017 8:03 pm

    I agree with Tim Spence. It appears that combustible housing was built in an area where wild fires were a high risk! The houses are ash but the trees remain.

  11. October 20, 2017 9:06 am

    Reblogged this on WeatherAction News and commented:
    A good summary of the issue, thanks Paul.

  12. Tim Spence permalink
    October 20, 2017 9:36 am

    High winds and simultaneous explosions of transformers plus cables burning, what kind of power surge can be related to wind? Someone who has done a lot of research on this subject is Andrew Dodson.

    $10 trillion would be needed to rebuild the electric grid to integrate solar and wind on a large scale

    Sudden gusting behavior for wind, and cloud cover for solar both introduce serious transient behavior in power supply.

    (He goes on to state that these resonances and transient responses are causing large scale damage to transformers, regulators and inverters.)

  13. John Cooknell permalink
    October 20, 2017 12:57 pm

    Lots of things interfere with power systems, the load has changed, electronic equipment introduces lots of issues, lightning strike etc etc. Poor maintenance and overloading is the most likely culprit.

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