1. Don't worry, be happy. The correlation of Wasatch snowfall with El Nino and La Nina is so low that there's no point worrying about it. The graph below shows the Alta Guard snowfall vs. the El Nino phase, as we've discussed in previous posts (e.g., El Nino Likely for the 2015–16 winter, 12 June 2015). Nobody can reliably predict what is going to happen in the Wasatch this winter, so don't listen to people who claim they can.
2. Beware of small sample sizes. Every El Nino period has somewhat different characteristics and weather. El Nino is an important player in climate variability, but it isn't the only game in town. Because of the strength of this El Nino, you'll see all sorts of predictions for the coming winter based on a small number of events. In some instances, a small sample can be dominated by a signal, but in others, you're just seeing noise. Buyer beware.
3. Play the odds. Based on existing understanding and a wide range of predictive tools, the most likely areas for above average snowfall and snowpack during the coming winter is in the upper elevations of southern California, Arizona, and New Mexico. The dice are somewhat loaded, but not as strongly, as one moves northward into the upper elevations of central California, southern Utah, and southern Colorado. Whether or not these areas get off to a fast start to the ski season in November and early December or get hammered on your vacation is completely at the whims of the weather gods. However, these are the areas that have the greatest likelihood of above average snowfall by the end of winter.
4. Remember that the friendly confines of the central Wasatch really are friendly. It snows a lot here. Yeah, last year sucked, but most bad years in the central Wasatch are still better than a good year elsewhere. Are you really going to leave the central Wasatch to ski the Arizona Snowbowl because they are likely to have an above average snow year? Everything is relative.
Dr. Jim, I keep reading that El Nino years are warm, at least in the northwest. Do you have any charts for temperature at Alta similar to the above chart for snow?
ReplyDeleteThat is correct for the northwest. Composites of temperature anomalies for El Nino periods are available at http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/composites/. Northern utah is a bit on the warm side on average early in the winter (e.g., DJF), but sits near average or even on the cool side in the spring. Of course, when you factor in the long term warming trend, this gives us an El Nino mean that is a bit above average.
DeleteOf course those are averages for all El Ninos and there are variations. CPC is pretty much going for elevated odds of above average in the northwest and giving northern no strong loading of the dice here.
I don't worry much about temperatures at Alta. If we learned anything last year it's that during a very warm winter: (1) most of the precipitation will fall as snow anyway at that elevation and (2) it's damn hard to melt snow on north facing aspects even when it's really warm. Of course if you want to ski other aspects...
The last 5 strong El Niño events were 1957-1958, 1965-1966, 1972-1973, 1982-1983, and 1997-1998. In these 5 years the Alta UDOT November through April (does not include any Oct. or May snow) snowfall averaged 554″ which is above the 70+ year average of 490″. Not a big increase but it does gives us hope.
ReplyDeleteHow much difference does 10 inches in the Alta base make for a snowboarder who rides mostly on groomers? (Well, technically none because Alta doesn't allow snowboarders so those (of us) who poach once in a while are not often on the groomers.) I spent a couple of weeks at Park City in early '83 and it was actually very good.
ReplyDeleteHey Jim -- some recent research has highlighted the difference between classic, warm "eastern" Pacific El Nino and warm "central" Pacific El Nino. Here's one paper looking at temperature, but I've seen others suggesting this impacts precipitation as well, with the "eastern" Pacific El Nino (what we have this year) being better for Utah precipitation: http://onlinelibrary.wiley.com/doi/10.1029/2012GL052483/full
ReplyDeleteTwo big caveats are (1) that I'm not sure these impacts would translate to localized sites like ski resorts and (2) now we're REALLY talking about small sample sizes.
Jon:
DeleteYeah, I'm aware of this work. It makes some sense to me that these different flavors of El Nino might have somewhat different impacts. However, the problem, as you note, is that you start to cut the sample size down further and further when you look for analogs from a small subset of events, raising the possibility that some of the difference is due to other factors. Thus, I think that work should be considered, but only along with other approaches. In my view, a holistic look at the evidence shows that there are some areas where the dice are loaded (e.g., far southwest) and others where they aren't, and northern Utah falls into the latter. Basically, we don't know where we'll end up this winter.
Will El Nino screw SE AK for snow this year?
ReplyDeleteProbably will be warmer than average, but last year was so bad, perhaps you won't notice.
DeleteHa! I wasn't here last winter........Ferry trips to high country.
DeleteSeems the last 2 "Very Strong" El Nino's have been favorable to the Wasatch. 1982-83 one was the biggest seasons ever...and the 97-98 was about 20% above average.
ReplyDeleteWhile it is true that a small sample size reduces confidence...having 100% of a small sample size giving a certain message (including a near record one) is (IMHO) not one to poo-poo either.
The only 2 "Very Strong (>2.0)" ENSO events in CA produced huge positive precip anomalies much further north than typical El Nino events...well up into Oregon. I have to wonder if the same is true for Utah? This is of course assuming that the current El Nino (already about +2.1 on the weekly average) continues to grow or at least maintain into the early winter.
Maybe wishful thinking but after a few relatively meager winters (comparatively speaking) in the Wasatch, we might be due, as Mother Nature, in her everlasting efforts to average things out, has a way to compensate in a hurry sometimes. :)