So does our current dry October offer any insight on our winter ahead? Below is the SWE plot from the 2004 - 2005 winter at the Snowbird Snotel. By November 1st a whopping 13.1 inches of precip had already fallen and the snowpack at Snowbird was already comparable to an average January 1st snowpack! This winter would go down as one of the snowiest since the snotel first started reporting in 1990.
Next I investigated the upper levels during winters after dry and wet Octobers. Winters ending in 2004, 2000, 2009, 1996, and 2013 had the 5 driest Octobers and below is the the mean 500 mb geopotential height anomalies for those 5 winters (Nov - Apr). There are above average height anomalies across the entire West suggusting ridging during those winters.
So where do we stand currently? Thus far the Snowbird snotel has received 1.3 inches of precip for the month. If we do not get any more this winter would be tied for the 2nd driest October, but there is still a lot of month left. Looking at the long range, however, I find it unlikely that Snowbird receives the 4.8 inches of precip necessary for an average October, which may slightly weight the odds for a below average winter.
Look for another post this week by another graduate student about the Arctic Oscillation and its role on our winter weather, and perhaps I will post again in November about how November precip is an even better indicator of December - April precip than October. Only if I am allowed of course.
post by Jeff Massey