Tahoe Daily Tribune — Tahoe Weather Discussed

Last February I had the pleasure of interviewing the creator and author of the increasingly popular blog Tahoe Weather Discussion. In that interview, founder Bryan Allegretto shared his unique take on weather forecasting, his predictions for the winter’s snow totals and his idea for an interactive forum focused specifically on Tahoe winter weather.

Allegretto has a knack for long range, localized weather forecasting. This propensity has lead him to make annual, pre-season predictions for liquid precipitation and the resulting snow totals in the basin. Last November, Allegretto officially called for 125% of average snowfall, but he revealed to me that he was hedging his bets with that number. Unofficially, he thought that the number could be much higher. With reports of 130-145% of average (depending on location), it’s fair to say that he hit the mark.

Although Allegretto has only two years of formal training, he is no stranger to winter weather, climate patterns and storm prediction. Born in New Jersey, he took an interest in winter weather around the age of five. His father was responsible for calling in the local snowplow drivers when weather was on the way. It was his father’s need for accurate weather predictions that gave him his first hands-on experience in forecasting. At that time “there was no weather.com, there was no satellite or radar that you could call up on your computer,” he explains. “You had to watch the local news or call the National Weather Service on the phone.”

Despite the difficulty in gathering the data needed to analyze weather, Allegretto describes himself as having been obsessed with snow storms early on in life. By the time he was in high school, he was accurately tracking storms heading for the Poconos and Catskills. Seeing a big storm on path, Bryan would often load up his car with friends and drive into the mountains with the intention of getting buried. The resulting adventure provided a legitimate reason to miss school and work.

It’s no accident that Allegretto now makes his home in the Tahoe area. The thrill he got from a really big dump of snow, and the love of riding a snowboard on top of it, left him only a few places in the lower 48 to pursue his passion. Since his arrival six years ago, he has been tracking storms, learning the local geography and studying area weather with a keen eye on historical patterns. In 2009, Bryan launched Tahoe Weather Discussion to create a place for others to read his forecasts, as well as discuss, learn about and contribute their ideas about pending weather.

This week I had the opportunity to reconnect with Bryan and see what’s new with the site, and to get his take on the winter to come. As per usual, his comments were conversational, informative and interesting.

Always open for suggestion, Allegretto has responded to requests from readers and stacked the web site with tools for forecasting, and planning your next big pow day. His easy to navigate site posts resort snow totals, links resort web cams, and loops satellite, radar and jetstream feeds from NOAA. Moreover, there are several features (such as posting your own backyard snow totals) that allow the reader to get involved with the discussion.

This site is truly a user friendly educational tool that will engage forecasters at all levels of the game. One way I’ve used the site in the past is to first look at the raw data found at Tahoe Weather Discussion. I then try to make my own forecast before reading Allegretto’s post. It’s a great way to test your skills. But, don’t be surprised when his post points out a huge piece of the puzzle that you may have missed.

Bryan is admittedly a stickler for comparative review of weather models. He likes to take current conditions such as ocean surface temperatures, the Madden-Julian Oscillation (MJO), the Pacific-North American Pattern (PNA), and a verity of other teleconnections (global patterns of atmospheric pressure, temperature and precipitation) and compare them to historically similar scenarios. In this way he has an actual pattern with which to critique and analyze the current models.

For example, last season we were in a strong La Nina pattern following the El Nino winter of 09/10. There are four similar patterns on the books from which Bryan could draw data for comparison. With this global-historical perspective he then looked at how these macro patterns played themselves out in the Lake Tahoe basin. From there, Bryan explains, “its just a matter of calculating the average.” Simple, no?

The problem is that detailed climate records only go back about seventy years in the Tahoe area. Beyond that, it’s just written anecdotal evidence and general environmental evidence. Currently, we are in a weak to neutral La Nina pattern coming off of one of the strongest La Nina winters ever observed. According to Allegretto, there is little in the records from which to draw comparisons to this particular pattern.

Bryan points out that in cases of weak La Nina conditions, other forces come into play that would otherwise be marginalized by the force of a strong La Nina. The local water temps off the west coast become a stronger factor, as does the MJO and the high pressure ridge that likes to sits off the coast of California.

Despite the limitation of the weather records, Allegretto is making predictions with the data available. This winter he’s calling for average precipitation in the Tahoe basin. However, he qualifies that statement saying that “its going to be a cold winter.” That prediction means that the ratio of liquid water to snow will expand. Meaning that despite average precipitation, we could see above average snow totals. Furthermore, Bryan thinks that this winter will be much more compact than the last, with “a late start and an early finish.”

I’m sure that we’ll all be watching to see what happens. In the meantime, tune into tahoeweatherdiscussion.com and get involved.

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