Several media outlets and activist websites are claiming that this year's low snowpack is a major cause of the wildfires (see example below).
Poor mountain snowpack and early melt-offs have translated to low reserves,
drying out grasses, trees, and shrubs that easily ignite and spread wildfires.
The facts are clear: such claims are wrong. The below-normal snowpack has had little impact in promoting recent wildfire activity.
To demonstrate this, let's consider the most impactful fire this summer, the Little Giant Fire near Lake Chelan, which was initiated by lightning on July 16 (see map below). The location of ignition (shown with a fire symbol) was at approximately 5000 ft.
We can get a good idea of snow evolution at the fire from the nearby Trinity Snotel site (see below).
The snowpack (snow water equivalent) at this location this year (black line) was generally below-normal (green line), but NOT a record low (lower red line).
If you look closely, the snowpack at this location melted out on May 2, when on average it melts out on May 11th. So, the snow was lost about 9 days early.
But that does not matter for this fire, since the fire occurred OVER TWO MONTHS (July 16). There is a large body of literature showing that only days to weeks are needed for surface fuels to become dry enough to burn after the snow has melted.
Furthermore, most of the water from snowmelt goes into streams and rivers and is lost to the region.
Thus, by mid-July there was plenty of time for the ground and vegetation to dry out, even in a normal year with full snowpack.
Want more proof for different fires?
Two other big fires were found to the east near the Columbia River: the Kailser Canyon and Molrite fires (see below), which started in mid-July
There is a nearby Snotel site at Gold Mountain (4500 ft, see map)
Below are the snowpack observations at this location (again, the black line is this year, green line indicates normal).
Way below normal snowpack! The snow melted out around April 8 rather than the normal of April 18.
Not important for a fire that would start THREE MONTHS LATER.
Still not convinced? Let's consider the largest fire, the Sinlahekin blaze near the Colville reservation in north-central Washington (see map).
There are two Snotel sites near the fire, and I will pick one of them (Salmon Meadow, 4460 ft, with the horizontal line in the map below).
This site had an abysmal snowpack, melting out on April 5, when normal is May 2. But normal melt-out was well over two months before the fire and thus the early melt-out was not relevant.
In summary, the regional snowpack melted out a week to a month early this year near the big regional fires. But that is immaterial for wildfire because the mid-July fire initiation was over two months in the future.
Even with normal...or ABOVE NORMAL... snowpack, the melt out would have occurred two months before the fire, allowing more than enough time for the soils and fuels to dry out.
In short, the low snowpack made little positive contribution to the large fires that were initiated by lightning in July.
Finally, to provide independent evidence of this lack of connection between Washington State snowpack and fires, the plot below presents the regional snowpack on April 1 (blue line) and the subsequent fires over the region (red line).
There is little correlation between them.
Why are some folks exaggerating the role of low snowpack on regional wildfires?
Perhaps because they are trying to find a way to blame the burns on climate change, rather than invasive grasses, poor forest management, human land disturbance, and human ignitions.
