This article was originally posted on OpenSnow.com by Meteorologist Joel Gratz.
Unfortunately, our luck has run out.
After 12 years of no major hurricanes (Cat 3, 4 or 5) making landfall in the US, Hurricane Irma and Hurricane Harvey both struck as major storms. To all those in Texas, Florida, and the Southeast, here’s to a speedy recovery and a hope that we are done with landfalling storms this season.
History Repeats Itself
As I was following the coverage of Hurricane Irma’s trek through the Atlantic Ocean, one graphic caught my eye.
This was shared on Twitter by Brian McNoldy, a hurricane researcher at the University of Miami.
The bottom image shows a day in September 2010 when there were three storms in the Atlantic and Caribbean, and compares this to the top image, which was on a day in September 2017 when there were also three storms in nearly the same areas.
Analog Forecast Technique
The atmosphere is chaotic, but there are also patterns that tend to repeat.
One way to make very long-range forecasts (3-6 months out in time) is to match the current weather pattern with past weather patterns, and then use the years with similar patterns as a template for what might happen in the current year. This is called ‘analog forecasting’.
Using the image above, the tropical weather pattern in the Caribbean and Atlantic had three storms in September 2017.
The image above also shows us that the tropical weather pattern in the Caribbean and Atlantic had three storms in September 2010.
If September 2010 is similar to September 2017, then perhaps the winter snowfall pattern during the 2010-2011 season will be similar to what we will see during the upcoming 2017-2018 season.
So, how much snow fell during the 2010-2011 season?
Before showing the 2010-2011 season’s snowfall, a WARNING:
Long-range forecasts are rarely accurate, and this article shows how most of last season’s forecasts were incorrect. Also, these forecasts predict the total snowfall over 6 months (a full winter season), but we know that skiing quality improves and degrades with storm cycles that last a few days to a week. Paying attention to a 1-10 day forecast is the way that you’ll find powder. A 6-month outlook like this offers little to no planning value for folks like us who are searching for pow.
Snowfall during 2010-2011
With that WARNING out of the way, here is the snowfall during the 2010-2011 season, shown as ‘percent of normal’. The blue dots show above-normal snowfall.
Notice that nearly the entire US had above average snowfall. Remarkable! Many of you will remember this as a phenomenal season, so I truly do hope that this weather pattern repeats itself.
La Nina In 2010-2011
The 2010-2011 season was a La Nina season (source), which means that there was cooler than average ocean water in the central Pacific Ocean and the storm track entered the US from the northwest.
Some forecast models are also pointing toward a trend for La Nina during this upcoming season, 2017-2018. While I do not have high confidence about La Nina for the upcoming season, it is encouraging that BOTH the analog forecast using hurricanes and the ocean models trending toward La Nina point toward a similar pattern as we saw during the 2010-2011 winter.
What This Could Mean For 2017-18
First, long range forecasts are usually not accurate. Don’t get too excited or depressed based on this article.
Second, even though long range forecasts stink, this article shows that the upcoming 2017-2018 season might just be similar to 2010-2011. The 2010-2011 season was a very good season.
Third, since the factors I discuss in this article are pointing toward a good season, I am getting a bit more serious about my powder planning. I am not locking in trips just yet (I am lucky to be able to plan last minute, I know), but I am starting to seriously consider how to take advantage of the powder if it comes.
Fourth and last, remember that long range forecasts are usually not accurate, so don’t let all of this talk about a repeat of 2010-2011 go to your head.
See Joel Gratz’s original post on OpenSnow.com
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