Cage Match: Nov-Dec 1976 vs. Nov-Dec 2017

By popular demand, we now compare Nov-Dec 2017 with the comparable start period of the "season that shalt not be named", the "drought year," or simply, 1976/1977.

The 1976/1977 season is the worst on record in the modern era (i.e., since WWII) in the Wasatch Range.  Records for Alta-Guard show a total seasonal snowfall (November through April of only 314.5 inches.  This is the second lowest on record next to 2014/15, when only 267.5" was recorded.

If 1976/77 was only the 2nd worst snow year at Alta, what makes it the worst ski season?  The lack of early season snowfall.  Nov-Dec 1976 produced only 30.5 inches of snow, 17.5 inches less than the second lowest comparable period on record, Nov-Dec 1962, and 102.5 inches less than Nov-Dec 2014.  In my book, a lack of early season snow is far worse than a lack of late season snow, mainly because you can't ski on dirt and the backcountry powder skiing is far less vulnerable to the sun during November and December than March and April. 

This season, Alta-Guard reported only 15 inches of snow in November.  I haven't seen their numbers for December, but Drew Hardesty of the Utah Avalanche Center notes in today's Salt Lake Tribune that Alta-Guard hasn't yet hit 50 inches for the season, and currently sits with the second leanest snowfall behind the 1976/77 season.  I think it will come in a shade under 50 inches.  Thus, in terms of snowfall, this season is bad, but not as bad as Nov-Dec 1976.

What about temperatures?  Nov-Dec 1976 had a mean temperature at Alta 28.8ºF, making it the 10th warmest such period on record.  This Nov-Dec it was 31.2ºF, good for fourth warmest.  One might be able to make an argument that this difference in warmth may have had some impact on melt and snowmaking.  In the case of the former, the loss of snow to melt on high-elevation north aspects is very small (or non-existent) this time of year when the sun angle is low.  Perhaps the difference in temperature has had some impact on snow losses down low during warmer periods (rain on snow, for example).  I'm going to guess that the impact is small, but stand to be corrected if someone can further than analysis with more data than I can look at in the short amount of time this morning.  I suspect that the situation on south aspects between the two seasons is a draw.  Near to nothing in both instances.  In the case of the latter, perhaps snowmaking conditions were a bit worse this Nov-Dec, but the argument is irrelevant since I don't think any resorts had snowmaking in 1976.  It would be interesting to go back and read some news reports from the 1976 holidays about what was happening at the resorts (alternatively, share your perspectives in the comments).  This Nov-Dec, we clearly have benefited from snowmaking in ways that were not possible in 1976 and, for resort skiers, that's probably a trump card surely making the start of this season better.

Now, getting to the meteorology.  If you are into El Niño and La Niña, you might be interested to know that weak El Niño conditions prevailed during Nov-Dec 1976, whereas weak La Niña conditions prevailed this Nov-Dec.  That's all I'll say about that.

The upper-level pattern during Nov and Dec 1976 was very high amplitude (i.e., wavy) across the Northern Hemisphere with a high amplitude ridge parked along the Pacific coast of North America and a deep trough over eastern North America.  This pattern kept much of the western US dry, but the eastern U.S. cold and snowy.

Source: ESRL

Source: ESRL

I was 9 years old at the time and living in upstate NY, and I still remember that as a very cold winter.  The extreme nature of the winter across the US sparked a good deal of research on climate and climate variability.  In what would have been a "rapid response" paper at the time, Henry Diaz and Robert Quayle published a paper in the October 1978 Monthly Weather Review arguing that January 1977 was probably the coldest month experienced in the eastern half of the U.S. in the last 200 years and that the 1976–77 winter set a new record for fuel demand due to the extreme cold in high population areas.

Source: Diaz and Quayle (1978)

This Nov-Dec was also characterized by a very high-amplitude pattern across the Northern Hemisphere.  However, the pattern over North America in November featured a ridge centered over the west-central U.S., rather than along the Pacific coast.

Source: ESRL

 This enabled storm activity in the Pacific Northwest, but kept the Southwest dry.  For northern Utah, the snowfall numbers for November 1976 and 2017 are nonetheless quite similar at Alta Guard, with 13.5 and 15 inches, respectively.   I haven't had a chance to dig into the water equivalent numbers to see how those compare and if there were any differences in the fraction of precipitation that fell as snow in the two years.

By December, the west coast ridge was dominant.  This is a pattern somewhat reminiscent of November and December 1976.  Alta-Guard, however, did a bit better for snow this December than in December 1976. 

Source: ESRL

It's not surprising that we see some similarities (and differences) between the two Nov-Dec periods.  Droughts in the west are frequently associated with ridging along the Pacific coast and that is a preferred area for ridge development.   Whether or not the remainder of this season evolves in a manner similar to the 1976/77 season remains to be seen, but my personal view is that analog forecasting based solely on local precipitation characteristics is not bound to be reliable over many cases.  My take is we just have to see how this will play out and hope that things shift for the better soon.

A few other thoughts:

1. The 1976/77 season was unbelievably bad in the southern Sierra Nevada.  Mammoth Mountains snowfall history (available here) shows a total seasonal snowfall of only 94" and no snowfall at all from October through December.  Four inches of that 94 fell before October.

2. Alta Ski Area's web site shows 74" in this Nov-Dec, but their observing site is higher up on the mountain.

3. I have not addressed the issue of observational representativeness and uncertainty in this post.  The Alta-Guard measurement site has changed over the years and this does affect snowfall measurements.  Similarly, I've never dug into the Alta site information to see if the location of the temperature measurements have changed, and that could affect the temperature comparison (there's a big difference depending on sun exposure, especially in December).

4. SNOTEL observations in the central Wasatch do not extend back to 1976.  It would be very interesting to utilize the manually collected snow course data to do a comparison.