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"... and it never failed. During the scanty snow seasons skiers longed for those epic powder days, and during the prosperous winters they lost all memory of the lean snow years. It was always that way"
-adapted for snow
from John Steinbeck - East of Eden
Final Powder Alert
Last winter review and outlook for next season.
Let's all say adios to winter of 2014-15 - thanks for nothin'
Washington ski areas had their worst snow season on record. See NWAC snow climatology: http://data.nwac.us/CLISNO/CLISNO.TXT. It may seem strange, but we had near normal precipitation this last fall/winter. The problem was the high snow levels. The snow levels were consistently 1000-2000 ft above normal. Below 5000 ft, there was little or no snow much of the season. I did get some decent ski days, but they were few and far between.
What Happened?
It could have been an arbitrary, wacky winter snow season. But there appears to be a connection between our poor snow season and elevated equatorial Pacific Ocean water temperatures. Here are some possibilities of what happened and an outlook of next winter season.
First, I don't think it was global warming at work. The warmth was caused by the unusual position of the Pacific high-pressure ridge.The high pressure was offset from normal in position & magnitude. This unusual offset is something climate models do NOT indicate will happen with climate change. However, it is important to note, higher snow levels is something we will see more often, as the climate shifts warmer in the decades to come. The higher snow levels this last season, are a good example of what more winters will look like in the future.
Next suspect: El Nino. It often causes a mild and dry NW winter. But this winter's El Nino was late in coming and very weak. Plus, it was not dry - we had normal winter precipitation. I don't think El Nino was a consideration this last winter, but the for the upcoming winter (2015-16) it may be the driving factor.
Next possibility: The unusual, huge "blob" of warm ocean water off the coast of North America. This blob actually started last year (2013-14 winter) and has now expanded. The high- pressure - not visa versa, caused the original blob. I think the blob may have modified incoming air masses, to be a tad warmer, but the ultimate cause is the position of the high pressure ridge, directing the storm tracks.
The prime suspect: It is well known that unusual areas of warmer Pacific tropical ocean water temperatures can affect our weather here in the mid latitudes (Seattle: 47 degrees north). What happens is the warmer tropical oceans produce weather patterns, which change the circulation from the tropics to the higher latitudes - modifying our winter storm track. Sure enough we've had a warm pool of tropical water in the equatorial Pacific (but not El Nino). That seemed to do the trick. The results were the Western U.S. received inconsistent snowfall/mild weather while the East Coast had big time snow and cold. The latest research from Dr Dennis Hartmann from UW suggests this idea.
See paper: http://www.atmos.washington.edu/~dennis/
Quoting.....
"Using a combination of analysis of past data and large ensemble
of specified SST (sea surface temperatures) modeling experiments, a strong case can be made that a variability of the ocean-atmosphere system originating in the Tropics is the mostly likely "cause" of the winter of 2014 anomalies" (winter of 2014 - 2015 too)
What is next?
All indications are the rest of the spring, the summer and fall will be warmer than normal and likely drier than normal. Remember our summers and early fall are typically fairly dry.
It is unknown if the tropical ocean temperatures will continue building warmth. A shift to full on moderate to strong El Nino (mild for the NW) is on the table, due to current observation and consistent modeling indications. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf
The pattern will not lock in until about September, so there is still time to change. El Nino will bring milder than normal temperatures for the upcoming NW winter, with fewer big storms, lack of lowland snow and below normal Cascade snow, less chance of big wind storms.
Finally...now the good news.
If an El Nino does develop as forecast one thing is likely. Even El Nino doesn't cause winter snowfall as sparse as the winter of 2014-15 - so next season has got to be better! |
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