High winds and dry conditions have fueled the Dixie fire burning in Plumas and Butte counties since it began in mid-July. As of Friday, the fire is over 240,000 acres and 24% contained.
NSPR's Alec Stutson spoke with Paul Ullrich, a Professor of Regional and Global Climate Modelling at UC Davis, about how regional weather patterns and climate change can affect firefighting efforts in the North State. Here are the highlights from their conversation.
This interview has been edited for brevity and clarity.
On current fire conditions in the North State
Well, the whole region there is pretty dried out, and as a consequence, much of the forest area around there is just basically ready to be ignited. However, when we look at variability in weather patterns, almost all of that is governed by wind direction, which is inevitably very hard to predict, particularly in mountainous regions.
On providing firefighters with weather predictions
(Firefighters) can use this information to do short-term predictability if they want to understand something like wind direction. That's predictability on the order of minutes to hours. But we can also look at the increased risk of wildfires. Given climatological conditions or weather conditions over a particular period of time, we can then identify those areas that are at the highest risk for a potential ignition event. And that can either be a natural ignition event, as in the case of the lightning storms that we had in 2020, which were predicted in advance. But it can also contribute to things like understanding of soil drying or vegetation drying and which locations may be susceptible, based on a long-term record of weather.
On the ways rising temperatures can cause an increased fire risk
We are seeing an upward trend in temperatures which is associated with anthropogenic climate change. This upward trend in temperatures is a contributing factor to the loss of snow and consequent soil drying that has been experienced throughout the Sierra Nevadas. And it has also led to higher temperatures which make it again contribute to more soil drying, drying of vegetation, and basically priming that vegetation for the potential transit of wildfires.
On other effects of climate change on the North State
Particularly in Northern California, we have rising temperatures associated with climate change. That plays a role in many other types of weather that is relevant to wildfires. So for instance, precipitation. If you have moister soil, that tends to preclude the formation of individual wildfires. It's anticipated that there will be increases in precipitation in Northern California, particularly during the winter season. Now that's coming in the form of rain instead of snow because of the higher temperatures, but that's a simple consequence of the fact that warmer air tends to hold more moisture with it. The air that we're seeing coming off the Pacific now is moister, that is it has more water vapor in it than it has historically, because of these higher temperatures.
