Our extreme weather: Arctic changes to blame?

By: Dr. Jeff Masters , 9:50 PM GMT on December 16, 2011

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"The question is not whether sea ice loss is affecting the large-scale atmospheric circulation...it's how can it not?" That was the take-home message from Dr. Jennifer Francis of Rutgers University, in her talk "Does Arctic Amplification Fuel Extreme Weather in Mid-Latitudes?", presented at last week's American Geophysical Union meeting in San Francisco. Dr. Francis presented new research in review for publication, which shows that Arctic sea ice loss may significantly affect the upper-level atmospheric circulation, slowing its winds and increasing its tendency to make contorted high-amplitude loops. High-amplitude loops in the upper level wind pattern (and associated jet stream) increases the probability of persistent weather patterns in the Northern Hemisphere, potentially leading to extreme weather due to longer-duration cold spells, snow events, heat waves, flooding events, and drought conditions.


Figure 1. Arctic sea ice in September 2007 reached its lowest extent on record, approximately 40% lower than when satellite records began in 1979. Sea ice loss in 2011 was virtually tied with the ice loss in 2007, despite weather conditions that were not as unusual in the Arctic. Image credit: University of Illinois Cryosphere Today.

Summertime Arctic sea ice loss: 40% since 1980
The Arctic has seen a stunning amount of sea ice loss in recent years, due to melting and unfavorable winds that have pushed large amounts of ice out of the region. Forty percent of the sea ice was missing in September 2007, compared to September of 1980. This is an area equivalent to about 44% of the contiguous U.S., or 71% of the non-Russian portion of Europe. Such a large area of open water is bound to cause significant impacts on weather patterns, due to the huge amount of heat and moisture that escapes from the exposed ocean into the atmosphere over a multi-month period following the summer melt.


Figure 2. The extent of Arctic sea ice loss in the summer July - August - September period in 2007 was about 1.4 million square miles (3.6 million square kilometers) greater than in 1980, according to the University of Illinois Cryosphere Today. For comparison, the lost ice coverage (orange colors) was equal to an area about 44% of the size of the contiguous U.S., or 71% of the non-Russian portion of Europe.

Arctic sea ice loss can slow down jet stream winds
Dr. Francis looked at surface and upper level data from 1948 - 2010, and discovered that the extra heat in the Arctic in fall and winter over the past decade had caused the Arctic atmosphere between the surface and 500 mb (about 18,000 feet or 5,600 meters) to expand. As a result, the difference in temperature between the Arctic (60 - 80°N) and the mid-latitudes (30 - 50°N) fell significantly. It is this difference in temperature that drives the powerful jet stream winds that control much of our weather. The speed of fall and winter west-to-east upper-level winds at 500 mb circling the North Pole decreased by 20% over the past decade, compared to the period 1948 - 2000, in response to the extra warmth in the Arctic. This slow-down of the upper-level winds circling the pole has been linked to a Hot Arctic-Cold Continents pattern that brought cold, snowy winters to the Eastern U.S. and Western Europe during 2009 - 2010 and 2010 - 2011.


Figure 3. West-to-east jet stream wind speeds at 500 mb (approximately 18,000 feet or 5,600 meters) in the mid-latitudes (40 - 60°N) over North America between 1948 and 2010. During fall (October - November - December) and winter (January - February - March), jet stream winds weakened by about 20%, from 13 - 14 m/s to 10.5 - 11 m/s. Spring (AMJ) and summer (JAS) winds changed little during this time period.

Arctic sea ice loss may increase the amplitude of jet stream troughs and ridges
The jet stream generally blows from west to east over the northern mid-latitudes, with an average position over the central U.S. in winter and southern Canada in summer. The jet stream marks the boundary between cold polar air to the north and warm subtropical air to the south, and is the path along which rain and snow-bearing low pressure systems ride. Instead of blowing straight west-to-east, the jet stream often contorts itself into a wave-like pattern. Where the jet stream bulges northwards into a ridge of high pressure, warm air flows far to the north. Where the jet loops to the south into a trough of low pressure, cold air spills southwards. The more extreme these loops to the north and south are--the amplitude of the jet stream--the slower the waves move eastward, and consequently, the more persistent the weather conditions tend to be. A high-amplitude jet stream pattern (more than 1000 miles or 1610 km in distance between the bottom of a trough and the peak of a ridge) is likely to bring abnormally high temperatures to the region under its ridge, and very cold temperatures and heavy precipitation underneath its trough. The mathematics governing atmospheric motions requires that higher-amplitude flow patterns move more slowly. Thus, any change to the atmosphere that increases the amplitude of the wave pattern will make it move more slowly, increasing the length of time extreme weather conditions persist. Dr. Francis discovered that during the early 1960s, a natural pattern in the atmosphere called the Arctic Oscillation increased the amplitude of the winter jet stream pattern over North America and the North Atlantic by more than 100 miles, increasing the potential for long-lasting weather conditions. The amplitude of the winter jet fell over 100 miles (161 km) during the late 1960s, remained roughly constant during the 1970s - 1990s, then increased by over 100 miles again during the 2000s. This latest increase in wave amplitude did not appear to be connected to the Arctic Oscillation, but did appear to be connected to the heating up of the Arctic due to sea ice loss. A warmer Arctic allows ridges of high pressure to build farther to the north. Since temperatures farther to the south near the bases of the troughs are not changing much by comparison, the result is that the amplitude of the jet stream grows as the ridges of high pressure push farther to the north. Thus it is possible that Arctic sea ice loss and the associated increases in jet stream amplitude could be partially responsible for some of the recent unusual extreme weather patterns observed in the Northern Hemisphere. This is preliminary research that has yet to be published, and much more work needs to be done before we can confidently link Arctic sea ice loss with an increase in extreme weather, though.


Figure 4. A high-amplitude jet stream pattern observed over the U.S. on December 13, 2011. Instead of blowing straight west-to-east, the jet was contorted into a southward-bulging trough of low pressure that brought cold temperatures and a snow storm to Southern California, and a northwards-bulging ridge of high pressure that brought record warm temperatures to portions of the eastern 2/3 of the country. The axis of the jet stream is marked by the strongest winds (green and light blue colors) at the top of the lower atmosphere (200 - 300 mb pressure level.)

Earlier snow cover melt on Arctic land also increases the amplitude of jet stream troughs and ridges
As Earth's climate has warmed over the past 30 years, the Northern Hemisphere has seen a dramatic drop in the amount of snow cover in spring (April, May, and June.) Spring is coming earlier by an average of three days per decade, and the earlier arrival of spring has significantly reduced the amount of snow on the ground in May. Less snow on the ground means the land surface can heat up more readily, and May temperatures in Arctic have increased significantly over the past 30 years. Dr. Francis found that the upper-level wave amplitude has increased by over 100 miles (161 km) in summer over the past decade, and this change appears to be connected to the decline in May snow cover. Thus, reduced May snow cover due to global warming may be causing higher-amplitude jet stream patterns, potentially leading to slower-moving weather patterns that favor extreme weather in summer, such as heat waves, drought, and flooding. Note that significant changes to the upper-level atmospheric circulation in spring were not observed, so springtime extreme weather events like the 2011 flooding and tornadoes in the U.S. cannot be connected to changes in the Arctic sea ice or high-latitude snow cover using this research.

Related posts
Florida shivers; Hot Arctic-Cold Continents pattern is back
Jet stream moved northwards 270 miles in 22 years; climate change to blame?

Jeff Masters

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Quoting VAbeachhurricanes:


Dear?

As yqt1001 said, that's his title. Or, rather, one of many, among which were "Highest Incarnation of the Revolutionary Comradely Love", "Ever-Victorious, Iron-Willed Commander", and "Shining Star of Paektu Mountain". Complete list here.
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Quoting Neapolitan:

I guess we'll see. The new leader will be his son, Kim Jong-Un--or, if you will, Kim Jong-Healthy--a Western-educated 20-something.

Also from Twitter: "North Koreans to commemorate Kim Jong Il's death with a hunger strike. It began about 50 years ago."


Ba da boom!
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Quoting yqt1001:


That's his official title. Dear Leader

Apparently, he died form over-working. The only time I have ever seen pictures of him are of him looking at stuff in North Korea (usually the army or a computer). Must be very difficult. XD

Also, to everyone who says that the world is a better place. Technically speaking nothing should change with his passing. North Korea is a country, not a terrorist group. "Taking out" the leader doesn't mean a change. A slow change should happen (Cuba-esque maybe?), but nothing rapid, at all.

I guess we'll see. The new leader will be his son, Kim Jong-Un--or, if you will, Kim Jong-Healthy--a Western-educated 20-something.

Also from Twitter: "North Koreans to commemorate Kim Jong Il's death with a hunger strike. It began about 50 years ago."
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Quoting WxGeekVA:


That's why I modified my borderline comment.
Close one.
Quoting VAbeachhurricanes:


If you could have anything for Christmas is would be a ________________
Nice censoring.
Member Since: August 14, 2010 Posts: 10 Comments: 17081
Quoting VAbeachhurricanes:


Dear?


That's his official title. Dear Leader

Apparently, he died form over-working. The only time I have ever seen pictures of him are of him looking at stuff in North Korea (usually the army or a computer). Must be very difficult. XD

Also, to everyone who says that the world is a better place. Technically speaking nothing should change with his passing. North Korea is a country, not a terrorist group. "Taking out" the leader doesn't mean a change. A slow change should happen (Cuba-esque maybe?), but nothing rapid, at all.
Member Since: November 19, 2010 Posts: 1 Comments: 1286
Quoting WxGeekVA:


That's why I modified my borderline comment.


If you could have anything for Christmas is would be a ________________
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Quoting washingtonian115:
And just when we start talking about the admin banning people because of fowl language the Doc makes a post XD.


That's why I modified my borderline comment.
Member Since: September 3, 2011 Posts: 13 Comments: 3475
And just when we start talking about the admin banning people because of fowl language the Doc makes a post XD.
Member Since: August 14, 2010 Posts: 10 Comments: 17081
Beautiful example of Kelvin-Helmholtz clouds here. Click on the little thumbnail pic at the top left.
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Quoting JeffMasters:
Wunderground releases its free iPhone app

We are proud to announce that our free Weather Underground iPhone app is now live in the iTunes store. Don't worry Android users, we anticipate that the Android version will be live on Monday.

I'll have a new post on Monday, about the Philippines flooding disaster.

Jeff Masters


If only i had a cool phone...
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Quoting Neapolitan:
Dear Leader Kim Jong-Il has died.


Dear?
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Quoting SPLbeater:


well next time you venture down to NC, stop by my house in Lee county for a few lol
My husband would kill me XD.I normally go to Ashville and Raleigh and Durham where my relatives are scattered out.
Member Since: August 14, 2010 Posts: 10 Comments: 17081
338. JeffMasters (Admin)
Wunderground releases its free iPhone app

We are proud to announce that our free Weather Underground iPhone app is now live in the iTunes store. Don't worry Android users, we anticipate that the Android version will be live on Monday.

I'll have a new post on Monday, about the Philippines flooding disaster.

Jeff Masters
2011: The Year the Evil Died

Osama Bin Laden=DEAD
Moammar Gaddaffi=DEAD
Kin Jong Il=DEAD

Wonder who else on the EVIL list will die in the next 13 days...
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting presslord:
posting Accuguess info here is kinda like walking into Starbuck's with a cup of Dunkin' Donuts coffee...


Which isn't illegal, more like frowned upon... "like *********** on an airplane, stupid terrorists"
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Quoting washingtonian115:
Yes.Northern Virgina is different from southern Virgina.When I'm travling to see my relatives in North Carloina They offer more "Southern hospitallity" than northern virginians do.And the people are just different down there.it's like two states in one XD.


well next time you venture down to NC, stop by my house in Lee county for a few lol
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Quoting WxGeekVA:


Exactly. They are smart enough to stay away from the crime den also known as the federal government.... XD


hahaha, ive lived in this state my whole live nova and down here, ready to leave. haha
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Quoting VAbeachhurricanes:


yeah, the smart ones sink to the bottom ;)
Quoting WxGeekVA:


Northern Virginia is waaaaaaaaaaaay different from Southern Virginia......
Yes.Northern Virgina is different from southern Virgina.When I'm travling to see my relatives in North Carloina They offer more "Southern hospitallity" than northern virginians do.And the people are just different down there.it's like two states in one XD.
Member Since: August 14, 2010 Posts: 10 Comments: 17081
Quoting VAbeachhurricanes:


yeah, the smart ones sink to the bottom ;)


Exactly. They are smart enough to stay away from the crime den also known as the federal government.... XD
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting VAbeachhurricanes:


The "D" word... so many possibilities... hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
Fine I'll censor it next time.I'll put the letter D and three stars following in behind it. :).
Member Since: August 14, 2010 Posts: 10 Comments: 17081
Quoting WxGeekVA:


Northern Virginia is waaaaaaaaaaaay different from Southern Virginia......


yeah, the smart ones sink to the bottom ;)
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Quoting VAbeachhurricanes:


Short and sweet lol


Thank you! One less maniacal psychopath in the world!!!! I feel safer already!
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting washingtonian115:
You two our from Virginia.So you all should stick together!!.(That's sorta like saying all the Floridians should stick together on here and we know that's never gonna happen).


Northern Virginia is waaaaaaaaaaaay different from Southern Virginia......
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting WxGeekVA:


Link please.... It's not on CNN...


Short and sweet lol
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Quoting WxGeekVA:


Not to be......?rude?.... per say, but did anyone make you the blog police....


im just giving a warning that if the right person sees that with authority, it could be removed.
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Quoting washingtonian115:
Wellll I said the "D" word plenty of times and haven't gotten banned thus far.However If I start saying other foul langage then I know I'll defentially be on the list for perma-bann.


The "D" word... so many possibilities... hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
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Quoting VAbeachhurricanes:


I did.
You two our from Virginia.So you all should stick together!!.(That's sorta like saying all the Floridians should stick together on here and we know that's never gonna happen).
Member Since: August 14, 2010 Posts: 10 Comments: 17081
Quoting VAbeachhurricanes:
So Kim Jong-il has died... is his son gonna take charge?


Link please.... It's not on CNN...
Member Since: September 3, 2011 Posts: 13 Comments: 3475
So Kim Jong-il has died... is his son gonna take charge?
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Quoting VAbeachhurricanes:


I did.


LOL!!
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting SPLbeater:


Rule #3. FOul Language is not allowed
Wellll I said the "D" word plenty of times and haven't gotten banned thus far.However If I start saying other foul langage then I know I'll defentially be on the list for perma-bann.
Member Since: August 14, 2010 Posts: 10 Comments: 17081
Quoting WxGeekVA:


Not to be......?rude?.... per say, but did anyone make you the blog police....


I did.
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Quoting SPLbeater:


yes, really. check the community standards :D


*** I'm censoring myself ***
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Quoting SharpObjects:
Is FOWL language allowed?

Cockadoodle- doo!!!


LOL

QUACK QUACK QUACK!!
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Quoting WxGeekVA:


Really.....?


yes, really. check the community standards :D
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Is FOWL language allowed?

Cockadoodle- doo!!!
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posting Accuguess info here is kinda like walking into Starbuck's with a cup of Dunkin' Donuts coffee...
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Quoting SPLbeater:


Rule #3. FOul Language is not allowed


Really.....?
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting washingtonian115:
Damn.That would be nice though to have some snow over the holiday break.And to see some decent snow fall in the mid-atlantic before the year ends out.More like a white New Years.


Rule #3. FOul Language is not allowed
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Quoting WxGeekVA:


Sadly, it has no support from other recent runs and other models. Until we see more support, I'm not buying it because I've already had my heart broken by two close calls with snow so far this winter...
Damn.That would be nice though to have some snow over the holiday break.And to see some decent snow fall in the mid-atlantic before the year ends out.More like a white New Years.
Member Since: August 14, 2010 Posts: 10 Comments: 17081
Quoting washingtonian115:
If I'm looking at that correctly it would seem that D.C get's some snow as well?.I sure hope so...and not any of this baby crap we've been getting as of late.o
r teasing would also be a good thing to say...


Sadly, it has no support from other recent runs and other models. Until we see more support, I'm not buying it because I've already had my heart broken by two close calls with snow so far this winter...
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting bappit:
SOPA is the Stop Online Piracy Act. It has generated a lot of dismay on the internet. For instance, see here.


Ah. Thank you for clarifying. Another attempt by the US Gov't to control our lives and take our freedom...
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting TropicalAnalystwx13:

See post 279, that image is for December 28, 2011, which shows a lot of snow for PA.
If I'm looking at that correctly it would seem that D.C get's some snow as well?.I sure hope so...and not any of this baby crap we've been getting as of late.o
r teasing would also be a good thing to say...
Member Since: August 14, 2010 Posts: 10 Comments: 17081
How many inches is the 18?
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305. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #45
TROPICAL STORM WASHI (T1121)
9:00 AM JST December 19 2011
===============================

SUBJECT: Category One Typhoon in South China Sea

At 0:00 AM UTC, Tropical Storm Washi (1000 hPa) located at 9.6N 113.3E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving west at 9 knots

Dvorak Intensity: T2.5

Gale Force Winds
===============
120 NM from the center in northern quadrant
80 NM from the center in southern quadrant

Forecast and Intensity
======================
24 HRS: 6.9N 108.9E - Tropical Depression
Member Since: May 24, 2006 Posts: 51 Comments: 45591
Quoting palmbaywhoo:
Are any models showing a possible snow event for PA anytime after the 30th? Heading up that way and hoping for some of the white stuff!

See post 279, that image is for December 28, 2011, which shows a lot of snow for PA.
Member Since: July 6, 2010 Posts: 113 Comments: 32267
303. HadesGodWyvern (Mod)
SOPA preposition is going be real strict with copyright material if the president of America signs the bill into law.
Member Since: May 24, 2006 Posts: 51 Comments: 45591
Quoting TropicalAnalystwx13:
lol, my comment about the upcoming season was removed for violating the Community standards? How?


some people out there, have no sense at all. they call this a weather blog. you post something about the tropical weather. its removed. WTF.

this comment might be removed, but i could care less because the senseless editers(excluding Jeff) need this message!
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please dr. jeff stick to your specialty
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Are any models showing a possible snow event for PA anytime after the 30th? Heading up that way and hoping for some of the white stuff!
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.