This is the driest winter on the record books so far. But is it unusual? The data shows yes and no…
For consistency purposes, I’m using data taken from the National Weather Service in Bismarck since they have data that goes back to the late 1800s.
This season, we have only seen 8.1 inches of snow. This is the driest winter so far… but with lots more winter and even the spring to go, it’s unclear whether we’ll end up staying in first place.
Outside of this year, it was the winter of 1980 and 81 that has the official title of the driest snow season on record with just under 12 inches of snow.
I went back and looked at the snow data for each La Nina year since 1950 (the data is below). Notice that there isn’t really any consistency in the total amount of snowfall. The La Nina pattern doesn’t mean much for snowfall.
So when you see the 13.6″ we got for the season in 2011 and 12… and compare it to the 100.3 inches just a few years prior in 2008 and 09, La Nina isn’t the factor for snowfall. There are many other factors involved when it comes to snowfall… where the jet stream located, how warm or cold the temperatures are, how much moisture is there in the air to work with.
This is a graph showing the snowfall each year since 1885. You’ll notice just how all over the place we are from year to year. The only consistency you see here is the steady increase in the last 30 years.
But what I think is more interesting than the snowfall… is the temperature profile we’ve seen this season so far and comparing it to years in the past. These are maps showing the winter temperatures for each year we were in a La Nina pattern since 1950 (data is below). Most of the time we have a colder than normal winter during the La Nina pattern. In fact, about seventy percent of the time that we’re in a La Nina winter, we end up with colder than normal temperatures. But we do have some La Nina winters that pan out to be warmer than normal… because La Nina – or El Nino for that matter – never guarantees a certain type of weather.
This year, a lot of the colder air we usually see has been locked up in the arctic with a stronger polar vortex, meaning the circulation that keeps the colder air north was tight and not letting outbreaks happen as much. But we’ve seen a disruption of this colder air… so that cold air is a little freer to move around. Quite often it takes a few weeks from the time it’s disrupted to the time it could impact us here in North Dakota. We have evidence that that certainly could happen by the end of January.