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The Pacific Ocean had a La Niña event that did not act the way it normally does; Kirstie Hettinga By Kirstie Hettinga, AccuWeather.com Staff Writer Aug 17, 2010; 1:01 PM ET
Thanks to a strong La Nina weather pattern, the West Coast is likely to see winter conditions opposite of what it endured last year.
According to AccuWeather.com Expert Senior Meteorologist and West Coast resident Ken Clark said, "The difference going into this winter, is going to be totally on the opposite side, last year we had a moderate El Nino going through the winter, that drastically changed this spring to a La Nina pattern."
Clark said that the La Nina will create drier and warmer weather in the Southwest.
Fast forward to winter
December 21, 2010 | 4:42 PM | By Craig Miller
FILED UNDER: Water, La Nina, Oceans, weather
Pacific ocean conditions that often portend a dry winter sure haven’t so far.
Scientists like to joke that “climate is what you expect, weather is what you get.” The relatively soggy winter so far is a classic example of that.
Satellite image from last weekend, showing storm systems marching across the Pacific toward California. (Image: NASA)
A closely-watched oscillation in the Pacific is in the La Niña phase this winter, creating colder-than-normal surface temperatures and distorting weather patterns. Usually a La Niña means drier-than-normal conditions for Southern California in particular and often for northern parts of the state as well. Not this year–at least not so far. The rain set multiple records over the weekend. Los Angeles has had a third of its average annual rainfall in a week. So what’s going on?
Kevin Trenberth, who heads the Climate Analysis Section at the Nat’l Center for Atmospheric Research, says lately there’s a monkey wrench in the works, in the form of a “blocking anticyclone.”
“In La Niña conditions, which is what we have now, the main storms that come into North America come barreling into Washington, Oregon and British Columbia more,” Trenberth told me in a phone interview.
But lately a persistent region of high pressure in the north Pacific is diverting storms south, into California. Trenberth says: “There’s a crapshoot or a random component to it, if you like, in the more northern latitudes, that’s adding some extra flavor to what’s going on, I think.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1831
by Gareth on June 26, 2011
The extraordinary sequence of extreme weather events during the last 18 months is probably the worst run of natural disasters since 1816, when a huge volcanic eruption at Mt Tambora cooled the earth enough to cause the famous “year without a summer“, according to a powerful blog post by Weather Underground founder Jeff Masters. He runs through the list, giving details of each:
Earth’s hottest year on record Most extreme winter Arctic atmospheric circulation on record Arctic sea ice: lowest volume on record, 3rd lowest extent Record melting in Greenland, and a massive calving event Second most extreme shift from El Niño to La Niña Second worst coral bleaching year Wettest year over land Amazon rainforest experiences its 2nd 100-year drought in 5 years Global tropical cyclone activity lowest on record A hyperactive Atlantic hurricane season: 3rd busiest on record A rare tropical storm in the South Atlantic Strongest storm in Southwestern U.S. history Strongest non-coastal storm in U.S. history Weakest and latest-ending East Asian monsoon on record No monsoon depressions in India’s Southwest Monsoon for 2nd time in 134 years The Pakistani flood: most expensive natural disaster in Pakistan’s history The Russian heat wave and drought: deadliest heat wave in human history Record rains trigger Australia’s most expensive natural disaster in history Heaviest rains on record trigger Colombia’s worst flooding disaster in history Tennessee’s 1-in-1000 year flood kills 30, does $2.4 billion in damage
Masters argument is straightforward:
…it is highly improbable that the remarkable extreme weather events of 2010 and 2011 could have all happened in such a short period of time without some powerful climate-altering force at work. The best science we have right now maintains that human-caused emissions of heat-trapping gases like CO2 are the most likely cause of such a climate-altering force.
There’s more heat accumulating in the system, and more water vapour in the atmosphere to drive weather events.
A naturally extreme year, when embedded in such a changed atmosphere, is capable of causing dramatic, unprecedented extremes like we observed during 2010 and 2011. That’s the best theory I have to explain the extreme weather events of 2010 and 2011–natural extremes of El Niño, La Niña and other natural weather patterns combined with significant shifts in atmospheric circulation and the extra heat and atmospheric moisture due to human-caused climate change to create an extraordinary period of extreme weather.
So much for the normal weather models working!
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