The 2017-2018 winter season featured the least amount of snowfall we have recorded since we moved to Nederland in July 2010. The total snowfall was only 110.1 inches, which is 43 inches below our normal of 153.1 inches. The table below shows the snowfall total for each of the winter seasons we have lived here. It also shows the total liquid precipitation for the water year (starting October 1) through June 1 of each winter season. The liquid precipitation from October 1, 2017 through June 1, 2018 was 10.93 inches, well below the average of 14.25 inches for this time of year:
The last column in the table shows the average El Nino Southern Oscillation (ENSO) 3.4 index for each snow season from October to June. It can be tricky to nail down a correlation between winter time precipitation here in the Front Range Foothills and ENSO. However, stronger ENSO episodes do seem to have some influence on how much snow and rain we receive. In the table, the negative ENSO 3.4 index values, below -0.5, represent La Nina conditions while the positive values above 0.5 represent El Nino conditions. Our two least snow seasons, 2010-2011 and 2017-2018, correspond to stronger La Nina episodes while our snowiest season, 2015-2016, coincided with a very strong El Nino.
Obviously, there are not enough data points to draw any absolute conclusions, but it has been noted that the Front Range and nearby cities such as Denver often see more up slope storms during El Nino years, particularly during the late winter and early spring. Interestingly, we had no snowfalls over 12 inches during the 2017-2018 snow season. The largest snowfall was 10 inches on October 10, 2017. Looking at our Snowfall Return Frequencies page, this is unusual. Most snow seasons feature about 3 storms of 12 inches or more of snow and nearly 5 storms of 10 inches or more.
We are running a deficit in precipitation so far this year, but the monsoon season is still to come and during a good year can bring plenty of beneficial precipitation.