A bit of relief may be headed to firefighters this week as rain is predicted for parts of Northern California that are still struggling with containing wildfires. According to KRON 4, meteorologists have predicted that by Thursday, a weather system coming in from Alaska should be providing some light rainfall to parts of the Bay Area, with much of the rain concentrated around the Santa Rosa/Napa area.
The National Weather Service detailed the predicted weather system's effect and overlaid it with a map of the currently still-burning regions of Northern California:
A major pattern change will take place Thu-Fri as a system drops down from the Gulf of Alaska with a chance of rain in most areas#bayareawx pic.twitter.com/pRfGxpPPBr— NWS Bay Area (@NWSBayArea) October 16, 2017
By the numbers, the rain doesn't seem like a whole lot, as none of the forecast rainfall amounts show rainfall above third of an inch, according to current predictions, at least. That said, confidence remains high that it will rain, and if it does, it will still provide a lot of support to firefighters in the form of increased humidity. As the Chron reports, the increased humidity in the air reduces the spread of fires and reduces the chance new fires can start, which is always a concern following an especially rainy period of time. They spoke with NWS meteorologist Charles Bell, who told them: "We’ll have much higher humidity values, a lot more moisture in the air. That part will really be helpful for eliminating any fire starts, the growth of fires, the spread of fires."
The rain poses a new set of hazards, though, as Curbed points out. They spotted this report from AccuWeather, which warns of potential flash floods and violent winds, the latter of which proved to be a key factor in the spread of the wildfires. In AccuWeather's report, meteorologist Faith Eherts says that "Increased runoff in burned areas could heighten the risk of localized flash flooding," and in the absence of vegetation, the amount of water needed to trigger a flash flood is much lower. But still, we're talking about less than a third of an inch, so this is probably overly alarmist.
KQED's Guy Marzorati attended a community meeting where fire officials answered questions from fire survivors regarding forthcoming efforts to get residents back to their homes. There, they fielded a question about whether the coming rainy season will potentially impact drinking water for the region, as the rain can wash away toxins exposed by the fire, taking them into the drains and sewers and contaminating things from there. According to CalRecycle's Chief Deputy Director Ken DaRosa, "Erosion control is an active and engaged part of the cleanup effort that goes on."
Related: Yes, All That Winter Rain May Be Triggering Earthquakes