Tuesday, October 26, 2010

La Nina Expected To Bring Much Colder And Drier Winter To South Central And Interior Alaska In 2010-11

Accuweather has published their long-range winter forecasts for North America, and winter is expected to be much colder and drier than normal throughout South Central and Interior Alaska. Local stories published by Dermot Cole of the Fairbanks Daily News-Miner and Craig Medred of Alaska Dispatch.

Accuweather attributes it in large part to the development of a moderate to strong La Nina, the phenomenon occurs when sea surface temperatures across the equatorial central and eastern Pacific are below normal. This in turn sucks the primary storm track southward to along the U.S.-Canadian border, which will allow cold, dry Arctic air masses to hunker down over Alaska.

The effect for Alaska could be lengthy cold snaps where temperatures could drop below -10F in Anchorage and below -40F in Fairbanks. For South Central Alaska, this poses a threat of a winter energy crisis fueled by sustained peak demand in the event of a prolonged cold snap. The problem: South Central's electricity supply is natural gas-dependent. But if the pressure through the natural gas lines to the compressors becomes insufficient due to sustained peak demand, the compressors shut down, and South Central Alaska could, in a worst-case scenario, go dark in mid-winter. This problem is explained in much greater detail in this June 6th, 2009 post.

The problem is not necessarily expected this winter, but Enstar is facing natural gas deliverability shortfalls during peak use periods as early as 2011-12; they propose to start importing LNG to make up for the shortfalls. In addition, Cook Inlet Natural Gas Storage Alaska has plans to convert a nearly depleted gas field on the Kenai Peninsula into a storage facility where excess gas from the summer can be stored for use during the winter.

In 2005, Anchorage forecaster John Papineau noted that when El Ninos or La Ninas are strong, they are more predictable than when weak, even though the long-range forecasts are still little more than sophisticated guesses as to what is going to happen. Papineau published his findings in a paper entitled "Winter Temperature Variability Across Alaska During El Nino Events"

For the lower 48, Accuweather notes that with the storm track hugging the U.S.-Canadian border, the Northwest, Plains, Great Lakes and New England are likely to suffer the worst of winter, with the southern tier from the interior Southwest to the Gulf Coast and Carolinas to experience a "non-winter", with above-normal temperatures and below-normal precipitation.

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