UPDATE 11/17/19 — Here’s our latest:
UKIAH, 11/16/19 — Pacific Gas & Electric has raised their rating for the “potential” that they’ll shut off power to our region from “not expected” to “elevated.” Essentially this means that weather forecasts indicated an somewhat higher chance of dry offshore-winds late next week, and that if those conditions materialize, and turn out to be severe enough, we may once again find ourselves in an intentional blackout.
PG&E calls these preemptive power outages, which they do to mitigate the risk of one of their uninsulated power-lines striking a tree, or being down, and sparking a fire, a “public safety power shut-off” or “PSPS.” But to all of you out there suffering from mild PSPS-PTSD (say that three times fast), as of tonight the risk has only been raised one level in their four level warning system, so there’s no need to start emptying your fridge and stocking your cupboard just yet, but this is worth monitoring.
The forecast is somewhat complicated by the fact that PG&E makes these assessments for broad regions, with most of Mendocino, Sonoma and Marin counties falling into Region 3, and far northeastern Mendo, as well as Lake and Napa counties falling into Region 4. During past red flag warnings this fire season, the danger has been concentrated in the inland high hills of Sonoma, Lake, Napa and Yolo counties, where an inversion layer keeps temperatures higher and humidities lower overnight, leading to an especially elevated fire risk. These higher elevations are also the place where the “Diablo Winds,” the hot, dry, offshore winds that are increasingly common this time of year (analogous to the Southern California Santa Ana Winds), blow hardest, with speeds topping 100mph during the last wind event.
Closer to the coast and farther north, the fire danger is far lower, and this has been the situation in most of Mendocino County during the past several red flag warnings. Even during the most severe wind event of the season, the last “historic” one that resulted in power being shut off continually for four days in most of our county, the winds were barely a breeze through much of Mendocino. Unfortunately, the specific local conditions are often not as important to whether or not we’ll be able to keep the lights on, as are the weather conditions where the major power transmission lines run — and in our case that means precisely those higher, hotter, drier areas of Sonoma, Lake, and Napa counties.
Whatever the specifics, one thing that is certain is that fire season, and grave fire risk, persist across the state as we enter the latter half of November without any significant rain fall. And the forecasts remains dismal, with no significant rain predicted through the end of Nov. In fact, parts of the state are on track to have the direst autumn in recorded history — yet another dismal record being broken in this new era of climate change.
For excellent insight into our meteorological predicament as climate change continues to weird our weather, following meteorologist Daniel Swain on Twitter is a good idea:
Here is PG&E’s weather forecast that accompanies the graphic above:
Saturday, November 16, 2019
NOTE: This forecast is based on weather conditions and fuel moisture content only and does not include other criteria used to determine whether a PSPS may be necessary.
Weather models continue to show potential for breezy to locally gusty offshore winds to develop mid-week next week across Northern California. The updated PSPS forecast now shows elevated PSPS potential for the middle part of next week for zones 2, 3, 4 and 5. There is still considerable uncertainty regarding the strength, timing and humidity levels with this system. Expect changes in the forecast moving forward. High pressure building over the territory this weekend results in much warmer than normal weather. Expect maximum temperatures away from the immediate coast to rise into the 70s to low 80s, which is 10 – 20 degrees above normal for mid-November. Fuel moistures are expected to drop due to the warm trend combined with breezy north to northeast winds across Northern California this weekend. Due to lack of precipitation, fuel moistures remain extremely dry for mid-November and generally below critical values.
Please note: This forecast is published daily by an operational meteorologist from PG&E’s Meteorology and Analytics team. This forecast has been customized for PG&E utility operations and should not be used for any other purpose or by any other entity. This forecast only provides a broad overview for a potential Public Safety Power Shutoff (PSPS) event in the next 7 days as determined from an analysis of forecasted weather, the potential for wind-related damage, and fuel moisture content in dead and live vegetation. It is not a fire danger forecast. The forecast is broken down by broad PG&E Geographic Zones numbered 1 – 9; however, PSPS decisions are made at more granular levels; thus, only a portion of a zone may experience a PSPS event. While a PSPS event may not be expected for an area, due to the interconnectivity of the grid any location within PG&E territory may be subject to PSPS event.PG&E
Parts of Southern California will be under a red flag warning this weekend due to the dry weather and high temps.