Winter Weather Forecasts
We've all heard that La Nina is forecast to influence our winter weather for a second consecutive ski season this winter. The cooler than average sea surface temps in the Equatorial Pacific mean different things to differrent regions, but for the most part backcountry skiers should be stoked because it normally means a good snow year for most western mountain ranges. I had the opportunity to attend the Oregon Chapter of the American Meteorological Society's annual Winter Weather Forecast meeting over the weekend where the pros discussed their takes on our upcoming winter.
Of course, La Nina talk factored heavily into the various discussions. The morning presentations included five different meteorologists' takes on the upcoming winter weather for the Northwest, specifically the greater Portland area. I took away a variety of interetsing facts and opinions from the various discusions, but the big picture theme that resounded through just about every forecast was that we (in the Northwest) can look forward to an above average snow season that is likely to have a slow start and a big finish. Sounds familiar doesn't it. I think we could sum up last season as an above average snow year with a slow start and a big finish.
Predictably, these guys are hesitant to really commit to too many specifics, and they use a lot of language like, "a better than average chance of a higher probability of above normal snowfall . . ." But they did offer up some details about their methods that were cool to hear. The various forecasters all rely on an analog approach where they look for similar historical conditions using a variety of weather indices and then crunch the various data to predict the future weather. A common theme among the various approaches was the similarieties between the approaching 2011 winter with that of 2008. There were a number of other similar years, including '89, '96 and '99, but 2008 was the closest match.
Here in Hood River, 2008 is remembered as the season with a great mid-December cycle that delivered three feet of snow just before Christmas in the low elevations of the Columbia Gorge. The skiing was great on local low-elevation hills, places that normally see little or no significant snowfall. It was, however, not until late January or arguable the first half of February that the upper elevations began to experience quality normal snowfall. In other words, it was a good snow year, but aside from the localized low elevation snow, good mountain snow started slowly and finished strong. If you want to immerse yourself in the various 2011 winter forecasts, you can read them all, along with all of their methods at the American Meteorlogical Society Oregon Chapter's website.