Mark Losleben - CU INSTAAR Research Staff
The following snowpack conditions on Niwot Ridge have been reported by Mark Losleben for November 2004. Select here for more information about these snowpack reports
Early Snow Season Greetings from Niwot Ridge!
This is just a preliminary report, as the first official snow measurement will be the end of this month. But how does the coming season appear to be shaping up at this early date? With the caveat that it is early, and anything can happen, this seasons snowpack is promising to be very different from the last. Last seasons heavy states are this seasons losers, so far. In general, the northern half of the western US states are below average, while the southern half are above. (This is an El Nino pattern). Last season, Oregon most often had the highest snowpack, and Utah near the lowest. The reverse is true now. Utah has 188% of average snowpack, compared to Oregon's 28%. Interestingly, the highest snowpack states have a Snowpack Index (SI) of greater than one (more snowpack than normal given the amount of precipitation received), in contrast to the states with the lowest snowpacks which have an SI of less than one.
Colorado is one of the blessed southern tier of states, although not anywhere as blessed as Utah. Roughly, Colorado shows a north/south split similar to the western US pattern, with the southern basins having greater snowpack than the northern basins, compared to their average. The state average snowpack is 111% and its cumulative precipitation since October 1 is 113%. The basin with the lowest snowpack is the Yampa/White showing 97% of average and 108% of average precipitation since Oct 1, and the Gunnison has the most; 133% snowpack/130% precipitation. Our South Platte basin is 107%/109%, and here on Niwot Ridge is 119%/145%, snowpack/precipitation, respectively.
What are the large-scale drivers for this change from last year (if indeed this pattern continues – a big IF)? Klaus Wolters MEI is positive as it was the last three years, so little help there, and the PDO index is not providing a strong signal as the most recent October value is barely negative compared to the past two years of positive values.
So, it will be interesting to see if this early season pattern holds. Until the end of the month,
Mountain Climate Program
University of Colorado