The Volcano That Blasted This Winter

July 20, 2017
Grimsvotn Volcano

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First Grímsvötn volcano erupted through a glacier. Then it exploded through the air. Finally, its debris changed the atmosphere so much that it blasted winter away from most of the US.

Most people don’t even know anything about Grímsvötn. It blew up in the middle of Iceland last May. Ash and chemicals roared 12 miles high into the air. Then everyone discovered that its ash was too high to mess with air travel to Europe and forgot about it. Unfortunately, the ash and chemicals are still lingering in the air, even if no one cares. They block out sunlight in parts of the Arctic. The air cools. Air pressures change.

What has happened is as simple as 1, 2, and 3.  

  1. Winds really make a difference in winter. They can blow Arctic air deep into North America or away from the US.
  1. Air pressure determines where the winds blow. In the North Atlantic, the low pressure near Iceland (called the Icelandic low) steers the winds.  
  1. The volcano in Iceland changed the air pressure over Iceland. The Icelandic low became very low.

Last week’s blog The NAO: The Crossing Guard of the Atlantic discussed a weather pattern called the North Atlantic Oscillation (NAO). When the cold Icelandic low is very different from the warm high air pressure in the mid-Atlantic, the Azores High, winds trap the cold Arctic air in the north. This is called a positive NAO and this winter the NAO was more positive than it has been in a century.

The Icelandic Low is so strong that it has created a positive NAO. Source: NOAA

Even now, the NAO is shifting between neutral and positive. It sometimes allows cold air to hit the US, and then it zips it out into the Atlantic. The cold doesn’t stay very long.

It doesn’t mean that it doesn’t get cold. A huge storm from Siberia, “The Beast from the East”, has hit Europe. China has shivered with temperatures below normal since January. Two cold spells plunged down and killed people in India.

Still the cold winter has avoided most of the US. The blast of Grímsvötn, a volcano in Iceland, has warped the normal Arctic winds. In the process, it warmed the US. If you are seeing flowers in February, point to the volcano!



About This Blog

Are you a weather watcher? Welcome to “Weather Whispers” by James Garriss and until recently, Evelyn Browning Garriss. With expertise and humor, this column covers everything weather—from weather forecasts to WHY extreme weather happens to ways that weather affects your life from farming to your grocery bill. Enjoy weather facts, folklore, and fun!

With heavy hearts, we share the news that historical climatologist and immensely entertaining Almanac contributor Evelyn Browning Garriss passed away in late June 2017. Evelyn shared her lifetime of weather knowledge with Almanac editors and readers, explaining weather phenomena in conversation and expounding on topics in articles for the print edition of The Old Farmer’s Almanac as well as in these articles. We were honored to know and work with her as her time allowed, which is to say when she was not giving lectures to, writing articles for, and consulting with scientists, academia, investors, and government agencies around the world. She will be greatly missed by the Almanac staff and readers.

Reader Comments

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Okay I guess you just

Okay I guess you just answered my question about why the OFA was so far off base with winter weather this year. I live in the Northeast and it said it was going to be below normal temps and more snow and I'm telling you it is as if we haven't had any winter at all. I like it but how could you be so far off? I guess it's the volcano, okay, you're off the hook, this time.

What,if anything might this

What,if anything might this mean for weather in South America, especially for the amount of snow that might fall in places like Bariloche AR or Las Lenas, Chile?

Since this winter was a

Since this winter was a strong la nina year what does that mean for summer if it sticks around with us during the spring? I hope this summer will be really hot because im a big fan of the hot summer days! I heard next winter will be an el nino year most likely. Which is the opposite and el ninos tend to force the jet stream down right? Which would mean next winter might be a different story.... Hopefully :)

I'm curious about why this

I'm curious about why this phenomenon gave us such a warm winter while Europe has had such a record cold winter? Why didn't the Azores High minimize the cold hitting Europe?

Second question: Does this mean that we should expect a warmer-than-normal summer across the US?

The NAO shaped by the

The NAO shaped by the Icelandic Low kept the Arctic air from entering the Atlantic. It had to go somewhere, so it went into Siberia. As more polar air poured in, the cold expanded through Russia, Eastern Europe and finally into England and France. Normally winter storms hit Europe from the Atlantic. They called this winter of Siberian cold "The Beast from the East."

There are clues that this summer might also be very hot, but it depends on a number of factors that are still changing.

I live in north Texas and our

I live in north Texas and our Winter has been warmer and wetter than normal. After the hottest driest summer of 2011 we welcomed the moisture. Out temps,however, have been on somewhat of a roller coaster.

I live in MI and we where hit

I live in MI and we where hit with a storm in some areas up to 20" or so
We have had alot of rain this winter
I was wonderin how this winter will affect our summer

No winter here. Golfers love

No winter here. Golfers love it. I'm in central Texas and 2011 summer was beyond brutal. Will this volcano make it as hot or even hotter this year? Please, no more rolling black outs, wells going dry, fires and vanishing lakes.

This is the first time ever

This is the first time ever in my life that I have planned a large outdoor party. I was wondering if it's possible to somewhat tell what the weather will be like on sat Mar 17th

I don't know where you are.

I don't know where you are. Good luck on the party!

In Endwell, NY which is in

In Endwell, NY which is in upstate New York, we had a very unusually warm winter. Last year, we had a blizzard practicly, dumping over 2 feet of snow. This year, we barely had enough snow to cover the grass.

I live in new hampshire we

I live in new hampshire we have had a very mild winter with only a hand full of snow storms

I live in central Virginia

I live in central Virginia and this was quite mild of a winter. The volcano eruption didnt change the USA weather patterns perminately did it? I sure hope not! That worries me that next winter will be warm too. I love winter and this winter has been miserable. We cant even ski this year. Its been too mild of a winter. Never seen a winter like this

The good news is that what

The good news is that what goes up, must come down. Typically, a large volcano only affects weather for two to three years, then the ash precipitates out.

I live in Utah, near Salt

I live in Utah, near Salt Lake City and I personally have enjoyed a very warm winter with very little snow. I am sure the ski/snow sport industry doesn't love this weather, but being someone origionally from San Diego, I appreciate a break in the winter time. Luckily the past few winters have been wet so we aren't hurting for too much moisture, so for now, I'll happily wait for spring in the not too terrible winter.

We in Fl have had unusally

We in Fl have had unusally warm winter to the point of flabgastering our weather reporters. It seems we have not had a winter at all in FL.Praying that the summer will not be a swelter and hi-hurricane season. God bless the midwest with their spring storms.

It looks like it will be hot,

It looks like it will be hot, but there is some good news. Scientists are saying that there is a 1-in-3 chance of a warm El Nino developing this autumn. That would really quiet down the hurricane season.

I am near St. Louis - this

I am near St. Louis - this winter has been very strange. We have had more thunderstorms than snow all winter long, including tornadoes. Do you think the tornadoes will slow down for us this year in the midwest?

I admit I am really concerned

I admit I am really concerned about this year's tornado season. We are in a La Nina, which historically causes a more active tornado season for the South and the Ohio River Valley.


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