Paul Rogers, Lisa M. Krieger and Matthias Gaffni, BAY AREA NEWS GROUP
Investigators are looking at power line failures as a possible cause of the historic fires.
The heavy winds that downed power lines Sunday night at the start of the deadly wildfires raging across Northern California were far from “hurricane strength,” as PG&E has claimed, according to a review of weather station readings.
On Tuesday, the Bay Area News Group reported that Sonoma County emergency dispatchers sent fire crews to at least 10 reports of downed power lines and exploding transformers as the North Bay fires were starting around 9:22 p.m.
In response, PG&E said that “hurricane strength winds in excess of 75 mph in some cases” had damaged their equipment, but they said it was too early to speculate about what started the fires.
However, wind speeds were only about half that level, as the lines started to come down, the weather station records show. At a weather station in north Santa Rosa where the Tubbs fire started, the peak wind gusts at 9:29 p.m. hit 30 mph. An hour later, they were 41 mph.
Similarly, at another weather station east of the city of Napa, on Atlas Peak, where the Atlas fire started, wind gusts at 9:29 p.m. peaked at 32 mph. An hour later they were 30 mph.
Both speeds were substantially under the speed that power lines must be able to withstand winds under state law: at least 56 mph.