If we look at the average temperature at Alta, for example, the largest outlier is not this year, but December 1980 – January 1981 (hereafter just 80–81).
There's a lot of missing data in the record for Alta, so I thought it might be wise to look at another site, in this case, Silver Lake Brighton. Indeed, it is 80–81 period that is the warmest on record.
The large-scale patterns for the two periods are actually pretty similar. 80–81 featured a western North American ridge and a deep North American trough.
The pattern is similar in 14–15, although it's not quite as amplified over the continental U.S.
So, it was a warm December to January period this year, but there has been warmer. Perhaps not surprising giving the strong ridging, the snowfall in 80–81 was also low, totaling 107 inches for the two months at Alta-Guard, just a bit more than the 102 inches observed this year.
A number of people have asked me if I think the bad snow years of late are a long-term trend. I don't think that they are for a couple of reasons. One is that there is a lot of variability in the climate system, so we need to expect some bad years and strings of bad years. Such years are in the instrumented record, as well as tree-ring reconstructions. A second reason is that although the warmth of this December–January and its impact on lower and mid elevation snow are consistent with the emerging long-term warming trend, the warmth this December–January has also been strongly accentuated by the anomalous ridge. In other words, what we have seen this year is primarily a reflection of the upper-level ridging and secondarily a reflection of that upper-level ridging occurring in a warmer world.
Whether or not climate change is increasing the variability in the climate system and perhaps increasing the likelihood of extremes like this year remains an open question being investigated by climate scientists today, and perhaps the subject of a future post.
Hi Jim, great analysis as always. Few questions
ReplyDelete1. Was it as cold and snowy in the east in 80-81 as this year
2. You did a post a year or two ago on snotel April 1 SWE trends. The result was the trend in Apr 1 SWE at 8000 feet was flat, the trend at 6000 feet was down. Don't recall exactly how you couched it, something like this was consistent w global warming. Your tone seemed more supportive than the "open question" phrase you use today. Am I reading too much, or are you changing your thinking as to the effects of increasing atmospheric carbon concentrations on mountain snowpack.
3. Do you know weatherbell.com? They did a forecast back in August that this winter in the East would be similar to last winter: cold and snowy, with possibly severe disruptions to transportation, heat and electric. Dumb luck or are they smart? If the latter, do you know what it is they know?
Thanks as always, keep up the good work, pray for more snow, less wind
1. Didn't look into this.
Delete2. The open question here is on *variability* meaning higher amplitude flow leading to extreme cold/warm and extreme dry/wet. Some might call this "extreme weather." No change in thinking on the overall long-term trends in temperature and fraction of precipitation falling as snow as a function of elevation. That post is still valid.
3. Don't know enough about their forecasts to comment.
I find it interesting that the average temperature appears to have no long term trend over decades at both the Alta site and the Brighton site. Many years ago, I attended a talk on statistical analysis to discover the "best Atmospheric variable" to analyze for a "fingerprint" of global warming. That variable is surface temperature. Could it be that the surface temperature in high mountain locations (in this case 700 mb) is so influenced by the large scale flow at 700 mb that we do not yet see a trend toward higher temperatures there?
ReplyDeleteI would be cautious inferring a long-term trend from those time series as they are uncorrected for instrumentation and site changes, and for a fairly brief period (Dec-Jan).
Delete1. Was it as cold and snowy in the east in 80-81 as this year?
ReplyDeleteNo. 1980-81 was 81% of normal snowfall at Northeast ski areas for which I have data. 1980-81 was arguably the worst ski season on record for North America as a whole (70% of average snowfall). 1976-77 was by far the worst for the West (record low in 5 out of 7 regions I track, 58% for the 7 western regions combined), but the the Northeast had its second best season at 131%. 2014-15 at the end of January was at 74%, which would be 3rd worst if it stays that way. A normal final third of the season would put 2014-15 into the 80-85% range, similar to 2011-12.
The Northeast ski areas are about average in snowfall so far in 2014-15, but the cold weather enhances snowmaking and prevents the rains and thaws that are most destructive to ski quality there. It's also important to remember that snowstorms in the eastern metro areas that generate the most publicity are not the ones that bring the most snow to the major ski areas of upper New England and Quebec.
Thanks Tony.
DeleteThanks Tony. CNN (there's a reliable source) reports Boston's average snowfall is 47 inches, they just had a week where it snowed 40 inches, and the last two weeks are above the average for the year
Deletehttp://www.cnn.com/2015/02/03/us/weather/
Wrong? Right, but local variablility? Colder than average across the Northeast, but some places average snowfall, others above average?
My thinking is if its unusually cold and snowy in Boston, it will be unusually cold and snowy in the Wasatch at some point in the future. Mean reversion. A few years ago it was 80 degrees in March at Stowe, this year its cold if not snowy at Stowe, and cold and snowy in Boston. Mid-60s in Salt Lake early February this year, another year hopefully soon, it will be cold and snowy.
People remember the outlier events like 1977 where it was very snowy in the East but dry in the West or vice versa. The year it was 80F in Stowe in March was 2012, which was a bad year in most of the West too, though there was lots of snow in the PNW and western Canada in 2011-12. In the long term the correlation of eastern vs. western snowfall is zero.
DeleteI just want to cry. :'(
ReplyDeleteI have a feeling we could make a run at 70 degrees tomorrow, although I believe that would be the earliest on record if we do.
ReplyDeleteIt would be interesting to see how SLC soundings compare for this season and 80-81, and what the SLC time series looks like. There is only one record high at KSLC for 80-81 DJF in late February, but we have 5 this year already (6 likely tomorrow) and a few extreme 700-mb temperature events, so the 2-3C higher at 700 mb is a bit surprising. Maybe that week around New Years is holding this year back from being truly special, although we still have the rest of February and another block next week to make up for that.
ReplyDeleteThe valleys have mixed out pretty well in the last few weeks, so I think that is a good part of it. Now that the valley surface temperature (and even lake temperature) have warmed up so much, it will be easy to set record highs if we stay in this type of pattern.
ReplyDeleteThe valleys have mixed out pretty well in the last few weeks, so I think that is a good part of it. Now that the valley surface temperature (and even lake temperature) have warmed up so much, it will be easy to set record highs if we stay in this type of pattern.
ReplyDeleteIs there any historical precedent for the sustained ridging pattern we've seen now for the past four years (i.e. what are the chances this will happen again next year)???
ReplyDelete