As Fall progresses I have been keeping an eye on the progress of the yearly snowfall. I use several methods to track this and have found an interesting disagreement between the methods. One measure is the snowpack which is a measure of how deep the snow is where the snow is located. The other is the snow extent which is how much area is covered by snow. The sources I use for the two measures are:
Snowpack: US Dept. of Agriculture
Snow Extent: Rutgers Snow Lab
I would expect that places that have deeper snow would at least show as having snow through the snow lab, but this is not the case. I understand that the snow lab isn’t very sensitive to mountain regions, but the disparity is so great that it makes me wonder about their data.
The snow extent for Oct 11th, 2011 is as follows:
This shows almost no snow in the contiguous United States. That would be fine, but the snowpack data is in stark contrast to this. What it shows is that the western United States has a much deeper snowpack than normal for this time of year.
On average, there is more than twice the normal snowpack for this time of year. Since it is the mountain tops that get snow first it is no surprise that the region is not widely covered in snow, but the snow in the mountains is significantly deeper than normal.
The question is which method is a better measure of what is going on with the Earth’s climate. It is extra snowfall in the mountains that will have an impact on glacier behavior, not how widely the snow is spread. That the snow is already deeper than normal is certainly interesting in the context of trying to understand what is going on with the Earth’s climate. This matches up well with my observations from the past summer when I was in Glacier National Park taking pictures.
In comparing the most recent month of September to historical snow extent, the comparison is very normal according to the data from the snow lab.
So the overall balance is fairly normal for the month of September, the depth of snow in the mountains is significantly deeper than normal for this time of year. This does not seem to be the type of climate change that is caused by global warming.
As always, I will be keeping track of the snowpack and extent throughout the winter. I suspect that it will be an interesting Fall/Winter this year even though the La Nina is very different than the one last year.