Via Cliff Mass Weather and Climate blog,
The tragic Camp Fire of northern California has killed at least 31 people, destroyed approximately 7000 structures, and basically leveled the retirement community of Paradise, California.
It appears that the fire was initiated by a failing PG&E power line in the Feather River Canyon just to the north of the town of Pulga (see map with arrow below). The time of failure was roughly 6:15 AM November 8th, with fire reported 15 minutes later.
A regional terrain map shows the position of the town of Paradise (big star) and the fire initiation (red oval).
But why did the fire start in the specific location northeast of Paradise? Even more interesting, the regional winds were blowing, but were not THAT strong–which probably explains why PG&E did not de-energize the power lines.
The map below shows the winds (see barbs, and max gusts over the past hour-red numbers) at 6 AM Nov. 8th, right before the power line failed. The red oval shows the failure location (click to expand). Sustained winds of 25 knots at the Jarbo Gap location just to the south of the failure, but mostly less. Jarbo Gap had a gust to 51 mph, and the other locations were less. You wouldn’t think that such winds would take down big high-tension power lines.
The Jarbo Gap RAWS site is about 5.5 miles to the S-SW of the failure site, and located on a ridge. Winds were from the northeast there, with gusts around 50 mph for several hours before the power line failed (see below).
So why did the power line fail where it did?
Could there have been much stronger winds there? Was the location of failure one of particular vulnerability?
I suspect the answer is yes. To gain a big clue, lets look at the terrain immediately around the failure location.
As you can see below, the accident location was within a canyon or gap, which was oriented to the northeast–ALONG THE LARGE SCALE WIND DIRECTION– upstream from the accident site.
Winds would tend to be channeled and strengthened in the Canyon (again the failure site shown by an oval).
But let’s zoom in. The power line failure occurred on the northeast side of a terrain feature, where the canyon narrowed. The terrain features would have blocked the flow and thus the winds could well have been substantially accelerated at EXACTLY the location of the failure.
If I am correct in my hypothesis about the failure of the PG&E power line, it has some major implications for how PG&E decides to de-energize their lines.
They can never put in enough wind sensors to know the winds everywhere and to sense every wind hot spot. So they may want to become much more conservative regarding when they shut down regional power lines (e.g., when winds gust above say 40 mph).
Or they can make use of more sophisticated wind forecasting/analysis technologies, using ultra-high resolution models (e.g. grid spacing of say 50 meters) to determine where the hot spots are and how they relate to the large-scale winds.
The DRI CANSAC model, which only has 2-km grid spacing, was going for quite high winds (sustained winds of roughly 45 mph) in the vicinity of the failure site (see below) and it was not resolving the canyon properly. So this was a real warning. Now the model could be overdoing the winds, but PG&E folks have to understand that there can be localized accelerations in vulnerable locations, such as the one where the fire stared.
Modern weather prediction technology provides a powerful tool for making decisions about de-energizing power lines and for warning vulnerable areas. The loss of life for events such as at Paradise can be reduced greatly with the application of this technology.
And, of course, there is something else….the rapid growth of people living at the vulnerable wildland-urban interface.
And I won’t get into the global warming aspects of this event (which I believe are quite minor). If I talk about global warming having minor impacts, I get very threatening emails and folks try to get me kicked off the local public radio station in which I talk each week.
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