this winters weather

Discussion in 'THE CROTON SOCIETY' started by pocomo, Dec 26, 2011.

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  1. pocomo

    pocomo Active Member

    Messages:
    337
    Location:
    10
    Saw an explanation of the weather patterns of the last two years and the difference from this years. The past 2 years there was a high pressure area centered over Greenland that forced the jet stream to bring storms and cold weather through the US. This year the high is centered over the mid Atlantic and the jet stream is is able to stay at northern latitiudes and the weather systems are bringing storms and cold air to the extreme northern US and Canada. Europe is staying warmer also. It also makes for (hopefully) a warmer, wetter SE US. Hopefully the high will stay in place.
     
  2. Bullwinkle

    Bullwinkle Esteemed Member

    Messages:
    1,450
    Location:
    DAVIE FL
    The Arctic Oscillation and its influence on winter weather
    The Arctic Oscillation (AO), and its close cousin, the North Atlantic Oscillation (NAO), are climate patterns in the Northern Hemisphere defined by fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores High. It is one of oldest known climate oscillations--seafaring Scandinavians described the pattern several centuries ago. Through east-west oscillation motions of the Icelandic Low and the Azores High, the AO and NAO control the strength and direction of westerly winds and storm tracks across the North Atlantic. A large difference in the pressure between Iceland and the Azores (positive AO/NAO) leads to increased westerly winds and mild winter in the U.S. and Western Europe. Positive AO/NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward. In contrast, if the difference in sea-level pressure between Iceland and the Azores is small (negative AO/NAO), westerly winds are suppressed, allowing Arctic air to spill southwards into eastern North America more readily. Negative AO/NAO winters tend to bring cold winters to Europe and the U.S. East Coast, but leads to very warm conditions in the Arctic, since all the cold air spilling out of the Arctic gets replaced by warm air flowing poleward. The winter of 2009 - 2010 had the most extreme negative NAO and AO since record keeping began in 1865; a very extreme AO/NAO also developed during the winter of 2010 - 2011. But this year, the pattern has flipped. The AO has been almost as strong, but in the opposite sense--a positive AO, leading to very warm conditions over the U.S. Unfortunately, the AO is difficult to predict more than a week or two and advance, and we don't understand why the AO can vary so much from winter to winter. The latest predictions from the ECMWF and GFS models show this positive AO pattern continuing for at least the next ten days. Real winter conditions won't arrive in the U.S. until the first week of January, at the earliest. Between now and the end of 2011, the only major winter storm the GFS model expects in the U.S. will be in the Pacific Northwest, on December 30 - 31.


    Courtesy Jeff Masters Weather underground
     
  3. Crazy for Crotons

    Crazy for Crotons Well-Known Member

    Messages:
    2,050
    Location:
    south Tampa, Bokeelia
    Hopefully this changes but the European forecast model shows very cold air headed for Florida next week (Jan 2-4). Accuweather shows 39F for me next Tuesday morning. The NAO and AO are still moderately positive so a sustained cold event is unlikely. It's now a race to get out of January before both the AO and NAO both go negative. February can still be cold but the longer days help some.
     
  4. Moose

    Moose Esteemed Member

    Messages:
    7,947
    Location:
    Coral Gables, FL Zone 10b
    Today 6:30 am 59F, 7:30 am 58F, 11:30 am 71F, 2:20 pm 74F - whats not to like?

    I stand by my prediction, no low below 45F in the Moose Land this season. :p
     
  5. rpebinger

    rpebinger Active Member

    Messages:
    104
    Location:
    Winter Haven, FL - 9A usually
    Ultimate low of 39F this morning up in the frozen tundra. No frost evident as of sunrise. I hope that Ray's prediction above of 39F in Tampa Tuesday is way off. TWC is showing 38F for Winter Haven on Monday 1/2/12. Hope everyone is well and Happy New Year (hopefully a warm one!)

    Rich
     

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