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Arctic Oscillation: Meet El Niño’s Cold Cousin

Arctic Oscillation: Meet El Niño’s Cold Cousin

Every few years, and more often in recent years, meteorologists start talking about a something called El Niño, or its opposite effect La Niña. Collectively known as Southern Oscillation, these two phenomena can have a dramatic effect on global weather patterns.

Less well-known, and even less understood than its southern cousins, but with just as much impact on the weather in North America, Europe an Asia, is a pattern called “Arctic Oscillation.” An atmospheric phenomenon, unlike El Niño and La Niña, which are caused by temperature shifts in the Pacific Ocean, AO refers to shifts in atmospheric pressure between the Arctic Circle and much of the Northern Hemisphere. In the “positive phase” of AO, atmospheric pressure lessens over the Arctic Circle and increases in southern latitudes. In its negative phase, it’s just the opposite. Atmospheric pressure is higher over the Arctic Circle and lower in the south. A related phenomenon, North Atlantic Oscillation, refers to shifts in pressure over the northern Atlantic Ocean.

What that means for our weather is that, when AO or NAO are in a positive phase, low-pressure systems — which cause cold, stormy weather — stay trapped in the extreme north. In a negative phase, those low-pressure systems are forced southward, bringing frigid air from the polar region down with them.

Over the last two winters, when cold temperatures and snow pounded much of the U.S. and Canada, AO was in an extremely negative phase. Combined with the effects of La Niña, which magnifies normal weather patterns, we’ve seen some extreme storms, prompting names like Snomageddon and Snowpocalypse.

We’re expecting the upcoming winter to once again be dominated by AO’s negative phase! On top of that, many meteorologists believe last year’s La Niña has returned for an encore performance. All I can say is, fasten your “sleet belts,” friends. As I said in the 2012 Farmers’ Almanac, we’re in for a “wet, wild winter!”

17 Responses

  1. before i read this artical i had never knew what none of this means i am still a little unsure but i never knew these things exsits

    by USAclimatereporter on Aug 9, 2012 at 11:11 am

  2. Thats what I want to hear cold and snowy.

    by jay weamer on Nov 23, 2011 at 7:35 pm

  3. will chatsworth ga be getting any snow like we did last year?

    by edge72 on Nov 19, 2011 at 12:04 pm

  4. I know we don’t have the extreme weather as in other parts of the country here in the San Francisco Bay Area, but for us the we had way more rain than normal last year and a fairly cool summer. My vegetable garden is proof that Mother Nature was messing with us!

    by Georgia on Nov 17, 2011 at 2:12 am

  5. Central MO, Crazy summer with weeks of 100+ temps…. Crazy winter this past season. A tornado rolled through town in May and the recent earthquake not far away makes me realize just how OUT OF CONTROL it is with Mother Nature in charge. Brace for a cold winter and more of the same next year. What we considered the “Norm” is no longer the case.

    by Ed on Nov 16, 2011 at 10:22 pm

  6. i live central mo. its always el or la here it seems.

    by jeffrey 5711 on Nov 16, 2011 at 10:11 pm

  7. Seems like Western WA has escaped the the cold weather of winter and the hot weather of summer experienced by most of the nation the past couple of years. The seasons tend to range between 30 and 70 degrees year round. Hate to complain but would like a bit more snow in winter and warmer temps during summer. On the upside we do seem to be protected from the more severe weather, so perhaps I should’t complain.

    by Linda on Nov 16, 2011 at 6:37 pm

  8. I’m in Texas too and any weather info is a big deal right now. We are starting to get rain again and some burn bans are lifting. I hope the rain continues, but could really do without most of the cold. The last two winters were too cold and too long for me. Praying for mild wet days and the return of nutritious hay for the farm critters.

    by Jennifer on Nov 16, 2011 at 2:34 pm

  9. I sincerely hope that here in Maine we don’t get a wet and wild winter. While I realize that we do need snow, I hate it! Even the cold is not much liked by me…So why do I stay in Maine? I love the State of Maine, weather and all and l would not live any where else:)

    by Linda on Nov 16, 2011 at 12:36 pm

  10. Have to agree with anyone in Texas, as I have close family there. They don’t need a year like this past year. Whenever the East got rain I wished we could catch it in a big net and fly it to Texas and other unusually dry places and pour it over the fires. Those people are hurting and didn’t get much help that I know of.

    by Nina on Nov 16, 2011 at 11:46 am

  11. Tommy, obviously the 2013 was a typo. I just briefly looked at the 2012 Almanac for winter weather, and it said exactly the same thing….”wet, wild winter”. Hopefully, our 2013 winter won’t be as bad.

    by Flo Ann on Nov 16, 2011 at 11:19 am

  12. Here in N. Central TX we could use for some cool weather and some MOISTURE. After breaking a lot of records for heat this summer, and having a horrid drought on top of the heat……. We are still basically above average for temps. Sure, I’m enjoying the beautiful weather, but I also realize what it means for us in the long run……… (Hay is almost requiring armed guards to ride shotgun!).

    by Tami on Nov 16, 2011 at 10:56 am

  13. Bite your tounge Kay … all we get is cool, damp and gray, day after day. It seems we only live half our lives … always waiting for a few weeks of summer. Not all of us are “snow monkeys” – so we wait. You can live outdoors most of the year even if you stay in out of the rain. Enjoy it … all 50 weeks of great weather…but think of us of us up in Michigan once in a while.

    by Brian on Nov 16, 2011 at 10:42 am

  14. Did you mean 2013 Farmers Almanac in the last sentence?

    by Tommy on Nov 16, 2011 at 10:11 am

  15. I wish we would get some of this stormy, cold weather in California. It is so BORING here!!! I am personally sick of sunny and mild. Ugh!!

    by Kay on Nov 16, 2011 at 10:03 am

  16. If you’re sharing thoughts, what about Central Texas? I don’t care what we get as long as it doesn’t include wind.

    by Scarlette on Nov 16, 2011 at 10:01 am

  17. Have your thoughts for my area in Cleveland changed any, if so how?

    by Nat on Nov 14, 2011 at 11:28 am

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