UPDATE 11/18/19 -- Here is our latest:
MENDOCINO Co., 11/17/19 — Pacific Gas & Electric is contemplating yet another preemptive power shut-off in advance of a wind event forecasted for the middle of this week. The National Weather Service’s Bay Area office has declared a fire weather watch for much of Sonoma, Marin, Napa and Yolo counties, and the Sacramento office has also declared a watch across the Sierra Foothill region and parts of the central valley, but there is, as of time of publication, no such watch declared for Mendocino County. (Read last night's coverage here)
The Mendocino County government has been contacted both by PG&E and by the California Office of Emergency Services (CalOES) and it is possible that maps showing the scope of the prospective shut-off could be made available to local governments by this afternoon — however, it must be noted as forecasts are not perfectly accurate and that, as has been observed in previous events, PG&E will likely not decide on the exact areas to shut off until right before the event.
PG&E is currently considering a shut-off for Wednesday and Thursday, and you can see their updates on the status of that at this website. It’s unclear if the weather event will meet the threshold to shut off transmission lines or just distribution lines, and thus whether we are facing the prospect of a large region-wide blackout, or something more localized and patchwork.
It should also be remembered that the areas thrown into blackout (if forecasts are borne out and PG&E decides to go through with this) will likely not exactly coincide with areas of dangerous fire weather. The power utility shuts off their power lines in an effort to prevent fires being sparked, either by tree limbs striking power lines, or by these lines being broken and falling due to high winds. What this means is that in cases where high-powered transmission lines need to be shut off, as was the case during the last protracted shut-off, areas far “downstream,” where the wind is but a whisper, can still find themselves thrown back into the pre-industrial era — and this to the great frustration of many people.
The Mendocino Voice spoke directly with Meteorologist Alex Dodd of the Eureka office of the NWS, who explained that the vast majority of Mendocino County is not expected to experience significant winds or dramatically low relative humidity. The exception to this will be along the eastern edge of the county, from east of Hopland up into the Cow Mountain area, and also in the National Forest areas east of Covelo. This region is expected to experience high winds of 20 to 30 miles per hour, and gusting up to 45 mph, at elevations above 2000 feet. However, the jury is still out as to how low the relative humidity (RH) will drop, a critical ingredient in the devilish mix of climatic features that is “fire weather,” and which propel the so called “Diablo Winds.”
As of Sunday afternoon the weather prediction can’t specify weather these RHs will get low enough to constitute critical fire weather, and the Eureka office is not yet ready to declare a fire weather watch, let alone a red flag warning, for Mendocino County. They hope that the forecast will be clearer by Monday evening. What is clear is that high winds are predicted for that area, beginning Tuesday night, peaking Wednesday afternoon, and dying down Wednesday night.
It’s also the case that the specific relative humidity might be less important than in other weather events because of the incredibly dry autumn that we’ve been experiencing in Northern California. Parts of the state are on track to have the driest fall on record, while others may tie earlier records of 60 years ago. What this means is that vegetation in the hills remains remarkably arid and combustible for this time of year.
Either way this wind and weather event is not expected to be nearly as potent as the one we experienced in late October, and in the best case scenario for Mendocino County this could mean that PG&E’s threshold for shutting off the high power transmission lines might not be met and we could see some small localized blackouts but not the general countywide event that occurred just before Halloween. PG&E has separate standards for when to turn off the distribution lines, which are closer to the ground, have weaker poles, and are generally closer to trees, than when to turn off the transmission lines which are generally higher, stronger and farther from vegetation. Still, even a wind event that only meets the threshold for distribution line shut-off could leave some of the easter portions of the county blacked-out, as happened in previous events.
Mendocino County CEO Carmel Angelo said that PG&E and CalOES contacted the county earlier today, and added that she will be providing local media outlets with information on maps as soon as they become available from CalOES or PG&E. During the last planned outage Angelo made several statements critical of PG&E, and especially of the quality and frequency of their communications with local governments. She reiterated those comments today, noting that during the last event, “It was very difficult getting information and then getting accurate information.” She also urged PG&E to do a better job of communicating not only with local governments, but directly with the public. She is also concerned that these power shut-offs could “create a public health event and nobody wants to see that.”Angelo will be attending the California Senate Energy, Utilities and Communications Committee meeting on Monday in Sacramento to speak on this issue and express these concerns.
Here's our coverage from last night: