The silly season is upon us with every Tom, Dick, and Larry putting together some sort of guess as to what this winter will be like. One of my favorites is below. Wet and "muggy" for the Pac Northwest. Yes, beware Washington your dewpoints could hit the mid-to-high 50s!
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| Source: http://weatheradvance.com/ |
As far as Utah is concerned, you know where I stand. There is very little skill in seasonal snowfall predictions for the Wasatch Mountains. We covered this
ad nauseam last year (see
Outlook for the 2013–14 ski season). The basic problem is that the main game in town for seasonal prediction is the El Nino/Southern Oscillation and our snowfall simply doesn't correlate very well with El Nino, La Nina or "No Nino" (a.k.a., neutral).
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| Source: Jeff Massey |
You can throw the alphabet soup of circulation anomalies like PDO, AMO, or NAO at the problem too and similarly there's simply not much correlation or forecast skill to be had for our neck of the woods.
Seasonal climate models? Well, here's the forecasts for February 2015. Take your pick. For northern Utah some are wet (green-blue) some are dry (brown-red). In virtual-reality land, you can have whatever February you want.
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| Source: NCEP |
So, after careful consideration, here's my winter outlook for the central Wasatch Mountains.
It's a pretty good bet, at least in the upper Cottonwoods where a bad year is usually good for 400" of snow above 8500 feet.
What is different among the seasonal climate models? Are they different models initialized with the same atmospheric state and same boundary conditions? Are some coupled ocean-atmosphere models? Pretty interesting. Given the chaotic nature of numerical integrations run out over months, I think one would expect them to be all over the place.
ReplyDeleteI believe they are run with different initial conditions. I suspect there could be other differences with regards to the ocean, ice and other states, but for the most part, you are seeing sensitivity to initial conditions.
DeleteEven during an El Nino year, one has to expect synoptic variability to play some role in the outcome over the western U.S., even in areas that show some correlation with the ENSO phase.