Today's LA Times article about the numerous wildfires north of San Francisco, CA, and in Northern California highlights in stark terms their current challenge. “…The sheer magnitude of what has already burned is sobering: about 1.3 million acres this month alone, with four more months of potential fire season to go. Only 2018 saw more land scorched in California — over an entire year.”
Wildfires in California are a normal occurrence, but two factors make the current situation more severe then we're used to hearing about at this time of year. One is a tremendous amount of lightning and the other is that August's dry weather creates a much different landscape then what meets the usual wildfires of October and November.
As of Monday, August 24, there are over two dozen major fires and multi-fire event “lightning complexes”. The San Francisco Chronicle has a very good live-map of the current wildfires and their status information. The LA Times explains that, “the blazes include the LNU Lightning Complex fire, which at nearly 350,000 acres is the second-largest fire in California history. The SCU Lightning Complex fire, at more than 347,000 acres, is the next largest. Combined, they dwarf the Thomas fire, which at 281,893 acres shattered the records just three years ago.”
The majority of the roughly 1100 residential and commercial structures lost and evacuations seen thus far have occurred since August 15, “which marked the start of what officials are calling a “lightning siege” of about 12,000 strikes that started an estimated 585 fires…” in the state, as noted by the LA Times.
I spoke with NFPA's Wildfire Field Representative, Dave Shew – also a long-time California resident – about the role lightning is playing in ignitions and he explained that usually at this time of year, weather that is generating lightning is more north in the Sierra Nevada Mountain areas, not down towards San Francisco, and never this concentrated. He stressed, “the widespread lightning siege in the Bay area is unheard of at this time of year.”
Lightning is also connecting with a landscape full of dry vegetation baking in August's heat. There is also little respite delivered by over-night lower temperatures that one would usually see in the fall months.
From his vantage point in Napa County, CA, north of San Francisco, Dave shared with me that these current wildfires, “seem to have a very different feel from our typical fall wind event fires. With those, we get hurricane force winds blowing everything up, but as soon as the wind stops blowing, the fires essentially go out. With these, we are still in the summer, with longer, hotter days, and very little or no cooling at night to allow for a “recovery” period.”
Dave went onto explain that these current fires, “appear to be largely topography driven, and yes, there are significant winds, but much more influence from dry vegetation and topography than normal.” As lightning findings this fuel, he explains that it is, “not uncommon for them to smolder for a week or more before they start really burning. So unfortunately, we are nowhere near out of the woods yet.”
1) Dave Shew, NFPA. 8-17-2020 PM Hennesey and Gamble Columns.
2) Dave Shew, NFPA. 8-24-2020 current smoke obscuring views from a similar perspective.
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