Weather

We're in for a drier winter, probably

winter-outlook-201112.jpgNOAA's forecast for the coming winter expects a drier than average wet season in Southern California, wetter months than usual up north and, sadly, continuation of the extreme drought across the southern plains of the central U.S. The entire southern sphere of the country, including Southern California, is "at risk of having above normal wildfire conditions starting this winter and lasting into the spring," the agency says. Hat tip: Emily Green at Chance of Rain.com.

Click the map to enlarge.

Also this interesting discussion of how the effects of a La Niña condition, which NOAA declared back in September, are counter-influenced by the "lesser-known and less predictable Arctic Oscillation:"

For the second winter in a row, La Niña will influence weather patterns across the country, but as usual, it’s not the only climate factor at play. The ‘wild card’ is the lesser-known and less predictable Arctic Oscillation that could produce dramatic short-term swings in temperatures this winter.

NOAA expects La Niña, which returned in August, to gradually strengthen and continue through the upcoming winter. It is associated with cooler than normal water temperatures in the tropical Pacific Ocean and influences weather throughout the world.

“The evolving La Niña will shape this winter,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “There is a wild card, though. The erratic Arctic Oscillation can generate strong shifts in the climate patterns that could overwhelm or amplify La Niña’s typical impacts.”

The Arctic Oscillation is always present and fluctuates between positive and negative phases. The negative phase of the Arctic Oscillation pushes cold air into the U.S. from Canada. The Arctic Oscillation went strongly negative at times the last two winters, causing outbreaks of cold and snowy conditions in the U.S. such as the “Snowmaggedon” storm of 2009. Strong Arctic Oscillation episodes typically last a few weeks and are difficult to predict more than one to two weeks in advance.


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