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The Vanishing La Niña

April 2, 2012

Credit: The Weathervane
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Here is the good news. The La Niña is vanishing.

One of the major factors that shaped the autumn and winter of 2011/2012 was the La Niña in the Pacific. This pattern of wind and water in the Pacific helped to shape weather around the world.

Here in the US, it helped create the drought that eliminated so much of the snow in the Western mountains. It created a two-year drought in Texas and left large stretches of the South high and dry.

By the middle of March, 58% of the contiguous US was dry or in drought conditions.

La Niña   SOURCE: NOAA

The La Niña is a large pool of unusually cool water in the Central and Tropical Pacific. It cools the air above it, altering not only the air’s temperature but also its ability of hold moisture. The air pressure changes and that, in turn, alter wind patterns. When over a million square miles of tropical air changes pressure, it changes wind and weather patterns around the globe, particularly in the tropics and the Pacific Rim.

The impact of a La Niña can be magnified or reduced by other climate factors. In the Northern Hemisphere, the wintertime behavior of the Arctic Oscillation (AO) can overwhelm the impact of a wintertime tropical oscillation. Normally a La Niña creates cold weather in Canada and the northern states. This year a positive Arctic Oscillation trapped the cold polar air north, leaving temperatures in most of the US positively toasty.


The Arctic Oscillation kept the La Niña from creating a cold winter. SOURCE: The Weathervane

This winter’s La Niña was weaker than the winter of 2010/2011, when the US froze and 49 of 50 states were covered with snow. It peaked in January and started to fade in February. At this point, most scientists expect La Niña to be gone by mid-to-late spring.

The good news is that to all intents and purposes, the La Niña is over. It is so weak that we are beginning to see a return to more normal winter. Rain has begun to return to the West and Texas. Storms lashed western states in late March, bringing near-normal snowpack to northern portions of the Pacific Northwest and welcome moisture, if not relief to central and southern portions of the West. Even parched Texas saw some relief, although 90% of the state remains in dry or drought conditions.

With La Niña fading, rains are returning to much of the drought-stricken USA. SOURCE: Wikipedia

Looking to the future, the majority of scientists expect the Pacific to be neutral this summer. Think of it – normal water and more normal weather.

Wouldn’t that be a nice change?

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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

What about Southeastern,

By vwall

What about Southeastern, Arizona? Are we going to have a decent monsoon this year?

Looking forward to more

By ~ Sil in Corea

Looking forward to more normal weather. Did Europe and Asia got the winter that missed North America this year?

I live in the southern

By Laurie VanZandt

I live in the southern Willammittee Valley of Oregon, and am looking forwards to some nice Spring weather...do you think we'll get some soon, with a nice warm Summer? I hope so!

I live in Northern Ohio I

By bassink

I live in Northern Ohio I hope the terrible rains stay away this year and return back to normal,gardening was bad the summer of 2011.

I noticed that our temps are

By kymom

I noticed that our temps are cooler, more normal for this time of year. 80's in March and April is way too warm already! Thanks for the heads up on normal summer weather!

I know here in the northeast,

By Angie Gentley

I know here in the northeast, the maple sugar season was early and short-but secretively, this Virginia born girl did a dance of joy when we saw temperatures in the 80s a few weeks ago. VT doesn't get many stretches of week-long, sunny, 80 degree weather. Fingers crossed that we see a warm summer, too-once it finally gets here, that is!

bye bye la nina! we wont miss

By brenda mcgraw

bye bye la nina! we wont miss you. Stay away from us next winter. we want to have a normal winter next year. It would be great if everything would just stay normal. What does that mean for summer here in the mid atlantic? Please not another 2009, that was barely a summer and I love my summers

Everything seems to indicate

By Evelyn Browning...

Everything seems to indicate a very warm summer. I'll write about why in another blog.

EVELYN PLEASE TELL ME THE

By PARCHED IN WEST TEXAS

EVELYN PLEASE TELL ME THE SUMMER OF 2012 IS GOING TO BE BETTER FOR US IN WEST TEXAS. I AM 34 YRS OLD AND HOPE TO NEVER SEE ANOTHER DROUGHT LIKE THIS ONE. WE STILL HAVENT SEEN RELIEF YET. WE ARE HOPING AND PRAYING THAT OUR MONSOON WILL KICK IN SOON AND BRING US RELIEF. WHAT DO YOU THINK IS IN STORE FOR US?

Looking forward to rain in

By ScruffyKitty

Looking forward to rain in the Florida Keys again. How does La Nina effect hurricane season in the Atlantic and Gulf?

Typically, La Ninas help

By Evelyn Browning...

Typically, La Ninas help create stronger east to west trade winds. More storms hit the western Gulf Coast, particularly Mexico, or wander up the middle of the Atlantic missing all land.

With the La Nina gone, there will be more tropical moisture (good) and tropical storms (bad) hitting the US.

YAY! We folks here in North

By mookzmom

YAY! We folks here in North Central TX have been waiting for this news! Hoping I'll have much better luck with my gardens this year. Love this update! Keep up the good work!

Thank you! I hope today's

By Evelyn Browning...

Thank you! I hope today's Texas storms brought you good rain and no tornadoes.

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