The Extremely Weird La Niña

January 2, 2012

Ski resorts are relying heavily on snow-making machines from Vermont to Colorado.

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Despite a cool La Niña shaping global weather, here in North America the weather has been amazingly warm.  Winter weather sulked in the West and refused to move east. Indeed, the weather got so strange that on Christmas there was more snow in El Paso, Texas, on the Mexican border, than in Toronto, Canada!

It has been very weird weather for a La Niña.

Expand picture! Credit: NOAA

Notice how a La Niña is supposed to shape the winter weather. It is supposed to produce cold wet weather in Western Canada and the Pacific Northwest. The South and Midwest are supposed to be hot. Texas and the Southwest are supposed to be dry while the Ohio River Valley is normally wet.

This did not happen this December. Indeed, throughout the month, the weather was more similar to the conditions normally produced by a warm El Niño. Almost all of Canada and the Northern Plains were substantially warmer than average (>5˚C or 9˚F) and the Southern and Central Rockies were freezing, averaging 8˚F (4.4˚C) cooler than normal. The Gulf was as warm as expected, but so was the entire East. The Desert Southwest and Southern Plains have been buried in snow which is great news for drought stricken Texas but very unusual for a La Niña.

December 20 – 31 – Temperatures (top map) and Precipitation (bottom) Top – Red means temperatures are more than 9˚F (5˚C) warmer than normal and dark blue is 9˚F (5˚C) cooler    Bottom – Dark blue means 200% more precipitation than normal while brown is less than 50% of normal

So what happened? Scientists have centuries of historical and tree ring data that indicate how La Niña events effects climate. Why is this event behaving so differently?

Scientists really are not sure, but here are some theories that I have heard so far:

  • Man-made global warming.
  • La Niñas fluctuate in strength. This one weakened through November to mid-December but is beginning to grow stronger. When the La Niña is weak, it lets the warm sub-tropical jet stream warm the East.
  • The Arctic Oscillation, the “wild card” of winter, remained positive and trapped the cold polar air mass north.
  • The North Atlantic Oscillation remained positive, which also traps the polar air mass north.
  • The Gulf Stream in the Atlantic is very fast this year, so the Atlantic has been extremely warm. That heat seeped inland throughout the East.

The combination of all these factors is rare, but it has happened in the past. I hope that you are enjoying the warmth (if that's what you like).

If snow and cold are more to your liking, there's lots of winter left in the calendar! In fact, we predict that winter will make a comback across the eastern U.S. and Midwest by mid-January!

How is your winter weather to date? Please report the weather in your area—and let us know what you think of it!


Evelyn Browning Garriss, historical climatologist, blogger, writer for The Old Farmer's Almanac, and editor of The Browning Newsletter, has advised farmers, businesses, and investors worldwide on upcoming climate events and their economic and social impact for the past 21 years.

Comments

Oh how I miss the

By aj123

Oh how I miss the snow....Long Island East Ender. I am surely the minority but this has been a DULL winter!

I live 300 miles from the

By Evelyn Browning...

I live 300 miles from the Mexican border and have 2 feet of snow in my yard. There is a 5 foot drift blocking one of my roads. I would love to share the snow with all of you!

midwests winter

By theatre_baby

I'm in Southern Illinois- typically, it's in the 20s and we've usually had a bit of snow already. I can't complain about this year- it's been steady in the 40s and 50s with sunshine.

very strange weather here in

By Jared Leff

very strange weather here in SD too. has been mostly 50-60 so far this winter, and we are used to minus 20, and minus 30 this time of the year, but i guess its starting to change back to normal this evening a bit. posted this 1-10-2012.

Not just in the US

By Joanne Sherman

I just got back from Germany and their weather has been unusually warm there, too. Didn't need my jacket, a sweater was enough most of the time. There were even geraniums blooming in some of the outdoor flower boxes in the villages!

Don't forget if we don't get

By Michele Prokopchak

Don't forget if we don't get a hard freeze at least 6-8 inches (or more) of the ground we are going to have a very"BUG"GY 2012--I don't relish insect bites. And I love cold and snow--bring it on Old Man Winter!

warm and loving it

By Catherine Boeckmann

Still no snow in NH.  I don't mind mild weather as it's preferable to an ice storm and keeps oil bills low. Plus, we can make snow on the ski mountains if we have to, but I definitely hope we'll get more precipitation over the winter season as it's good for the gardens come spring! Thanks for the great post, Evelyn, as always.

winter weather

By Leland

Do you think the earthqaukes under the ocean releasing hot gases could have much more of an affect than we think.

I think they do, but not in

By Evelyn Browning...

I think they do, but not in this case. There is a correlation between seismic activities in the East Pacific Rise and warm El Niños, not cool La Niñas. The area between the South Pacific tectonic plate and the Nazca plate off South America is a huge volcano field. When these volcanoes are going off, our instruments read the accompanying earthquakes.

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