La Nina Likely to Persist into Winter

Conditions in the equatorial Pacific Ocean that gave Alaska its unusual summer this year are likely to persist into the winter.

The National Weather Service confirms that La Nina has re-emerged in the tropical Pacific Ocean and it’s anticipated that it will gradually strengthen and continue into winter. A strong La Nina could impact weather patterns in Alaska. The reemergence of a La Nina has prompted forecasters with “NOAA’s Climate Prediction Center” to upgrade last month’s La Nina Watch to a La Nina Advisory. Mike Halpert is the deputy director of the Climate Prediction Center. He says La Nina winters often result in drier than normal conditions across the southern tier of the U.S. with wetter than normal conditions across the Pacific Northwest. Halpert is quick to point out that a La Nina should be seen as just a contributing factor to a particular weather pattern.

La Nina is basically a phenomenon where cooler than normal sea-surface temperatures cause changes to weather patterns. Halpert says the  threshold used is just a half a degree Celsius below average.

It believed that the 2010-2011 La Nina contributed to extreme weather across the globe.  Halpert says that included record winter snowfalls, spring flooding and a drought across much of the U.S.

Halpert says that La Nina’s typically occurs every three to five years but about half the time La Nina’s occur in back to back years.

La Nina conditions typically last for about nine to 12 months but sometimes the event can persist for as long as 2-years.    The name means “the girl” in Spanish and its counterpart is El Nino, which features warmer than normal sea surface temperatures.  It’s anticipated that the reemerging La Nina will influence “NOAA’s” official winter outlook that will be released next month.

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