Showing posts with label Precipitation extremes. Show all posts

Written by fatih al-farahat in ,


Models predict extreme precipitation, extremely low-pressure system for Northwest U.S. for November 1-2, 2010

Major Rain and Flooding Event Approaching


by Chris Mass, Cliff Mass Weather Blog, Seattle, Washington, October 28, 2010
Well, I was having some fun in my last blog, but this one will be serious. The reason? A major rain and potential flooding event may be coming, one that could impact some people's lives. But some uncertainty remains, and I will try to be upfront with that as well.

During the next few days, a disturbance off of Asia (Typhoon Chaba) will move northward, turn into a midlatitude cyclone and amplify into an extraordinarily deep, low-pressure center (see graphic). We are talking about 939 mb! (Compare that to the 955 mb over the Midwest that everyone was excited about two days ago.) There are so many isobars near that low the graphic is turning black!
PLEASE CLICK ON FIGURES TO ENLARGE

The monster storm, huge in scale and possessing hurricane force winds, will produce giant waves -- greater than 50 ft. high.  I could fill an entire blog about this storm...but there is a more acute worry here at home.

As the low pushes into the Gulf of Alaska it will result in the establishment of a very strong, moist current heading right for our region. You know the names -- "atmospheric river" is the generic term and our version is often called a "pineapple express."  The next graphic presents the early stages of this feature (Monday AM)....the total amount of water vapor in a vertical column is being shown:


You can see the current of moist air heading right for us.

Here is the 24-h rainfall prediction ending at 5 AM Tuesday. Red indicates 5-10 inches of precipitation over the Olympics, north Cascades, and mountains of southern BC. Precip decreases rapidly to the south.


A looks at a closer view for the same period below. A profound rainshadow will also exist NE of the Olympics. I am sure the National Weather Service will be putting out some statements on potential flooding of rivers coming off the Olympics and N. Cascades. At this point, it does not look like a situation that would produce urban flooding over the Puget Sound population areas.

The plume of atmospheric river air over us on Monday and Tuesday will feel warm, moist....almost tropical after the cold weather. Freezing levels will rise to 8,000-10,0000 ft., and a lot of the new snow will melt (sorry snow lovers).

I should be clear that there is often a lot of uncertainty with these cases of tropical storms converting into midlatitude systems. But the computer models have really locked on to this solution, and we are close enough now in time that I am believing it. Let's face it, it is really extraordinary we can do this at all.
Link:  http://cliffmass.blogspot.com/2010/10/major-rain-and-flooding-event.html

Written by fatih al-farahat in ,


Paul Douglas, Jeff Masters: October 26, 2010, weather bomb breaks all time low pressure records


Masters: “Strongest storm ever recorded in the Midwest smashes all-time pressure records”

'Weather bomb' hits Midwest with power of major hurricane

by Joseph Romm, Climate Progress, October 27, 2010
My dad was the biggest Republican that ever walked the earth. He always said: “Actions have consequences.” To pretend that a 38% increase in greenhouse gases isn’t going to have any impact, that we can have our cake and eat it too, and smear it all over our face, and maybe have our grandchildren deal with the hangover, I think it is immoral.
That’s Minnesota meteorologist Paul Douglas in an exclusive interview with Brad Johnson about the “weather bomb” that just hit and the global warming deniers that populate his state.
Weather bomb
Visible satellite image of the October 26, 2010, superstorm taken at 5:32 p.m. EDT. At the time, Bigfork, Minnesota was reporting the lowest pressure ever recorded in a U.S. non-coastal storm, 955 mb. Image credit: NASA/GSFC.
But let’s start with meteorologist Jeff Masters, who puts this staggering superstorm in contextand examines the climate change angle:

The mega-storm reached peak intensity late yesterday afternoon over Minnesota, resulting in the lowest barometric pressure readings ever recorded in the continental United States, except for from hurricanes and nor’easters affecting the Atlantic seaboard. So far, it appears the lowest reading (not yet official) was a pressure of 28.20″ (954.9 mb) reduced to sea level reported from Bigfork, Minnesota, at 5:13 p.m. CDT. Other extreme low pressures from Minnesota during yesterday’s storm included 28.22″ (956 mb) at Orr at 5:34 p.m. CDT, 28.23″ at International Falls (3:45 p.m.), and 28.23″ at Waskuh at 5:52 p.m. The 28.23″ (956mb) reading from International Falls yesterday obliterated their previous record of 28.70″ set on Nov. 11, 1949, by nearly one-half inch of mercury–a truly amazing anomaly. Duluth’s 28.36″ (961 mb) reading smashed their old record of 28.48″ (964 mb) set on Nov. 11, 1998. Wisconsin also recorded its lowest barometric pressure in history yesterday, with a 28.36″ (961 mb) reading at Superior. The old record was 28.45″ (963.4 mb) at Green Bay on April 3, 1982. The previous state record for Minnesota was 28.43″ (963 mb) at Albert Lea and Austin on Nov. 10, 1998. 
Yesterday’s records in context
Yesterday’s 28.20″ (955 mb) low pressure reading in Minnesota breaks not only the 28.28″ (958 mb) previous “USA-interior-of-the-continent-record” from Cleveland, Ohio, during the Great Ohio Storm of Jan. 26, 1978 (a lower reading in Canada during this event bottomed out at an amazing 28.05″/950 mb), but also the lowest pressure ever measured anywhere in the continental United States aside from the Atlantic Coast. The modern Pacific Coast record is 28.40″ (962 mb) at Quillayute, Washington, on Dec. 1, 1987. An older reading, taken on a ship offshore from the mouth of the Umpqua River in Oregon during the famous “Storm King” event on January 9, 1880, is tied with yesterday’s 28.20″ (955 mb.) 
The lowest non-hurricane barometric pressure reading in the lower 48 states is 28.10″ (952 mb) measured at Bridgehampton, New York (Long Island), during an amazing nor’easter on March 1, 1914 (see Kocin and Uccellini, “Northeast Snowstorms; Vol. 2, p. 324, American Meteorological Society, 2004).  The lowest non-hurricane barometric pressure reading from anywhere in the United States was a 27.35″ (927 mb) reading at Dutch Harbor, Alaska, on Oct. 25, 1977. The lowest hurricane pressure reading was the 26.34″ (892 mb) recorded in 1935 during the Great Labor Day Hurricane… 
… the famed storm that sank the ore carrier Edmund Fitzgerald in 1974, killing all 29 sailors aboard, was weaker than the current storm. Indeed, I wouldn’t want to be on a boat in Lake Superior today–sustained winds at the Rock of Ages lighthouse on Isle Royale were a sustained 68 mph, gusting to 78 mph at 3 a.m. EDT this morning! 
Yet Another Remarkable Mid-latitude Cyclone so far this Year!
Yesterday’s superstorm is reminiscent of the amazing low pressures reached earlier this year (Jan. 19-22) in the West, where virtually every site in California, Nevada, Utah, Arizona, southern Oregon, and southern Idaho–about 10–15% of the U.S. land area–broke their lowest on record pressure readings. However, the lowest readings from that event fell well short of yesterday’s mega-storm with 28.85″ (977 mb) being about the lowest recorded at any onshore site. 
Commentary
We’ve now had two remarkable extratropical storms this year in the U.S. that have smashed all-time low pressure records across a large portion of the country. Is this a sign that these type of storms may be getting stronger? Well, there is evidence that wintertime extratropical storms have grown in intensity in the Pacific, Arctic, and Great Lakes in recent decades. I discuss the science in detail in a post I did earlier this year. Here is an excerpt from that post: 
General Circulation Models (GCMs) like the ones used in the 2007 IPCC Assessment Report do a very good job simulating how winter storms behave in the current climate, and we can run simulations of the atmosphere with extra greenhouse gases to see how winter storms will behave in the future. The results are very interesting. Global warming is expected to warm the poles more than the equatorial regions. This reduces the difference in temperature between the pole and Equator. Since winter storms form in response to the atmosphere’s need to transport heat from the Equator to the poles, this reduced temperature difference reduces the need for winter storms, and thus the models predict fewer storms will form. However, since a warmer world increases the amount of evaporation from the surface and puts more moisture in the air, these future storms drop more precipitation. During the process of creating that precipitation, the water vapor in the storm must condense into liquid or frozen water, liberating “latent heat”–the extra heat that was originally added to the water vapor to evaporate it in the first place. This latent heat intensifies the winter storm, lowering the central pressure and making the winds increase. So, the modeling studies predict a future with fewer total winter storms, but a greater number of intense storms. These intense storms will have more lift, and will thus tend to drop more precipitation–including snow, when we get areas of strong lift in the -15 °C preferred snowflake formation region.
You can read more of the weather records smashed by this superstorm at Capital Climate.


Here is more of Brad Johnson’s Wonk Room post:
Fueled by fossil fuel pollution, an unprecedented, freak “land hurricane” swept through the continental United States, leaving a path of devastation from Saskatchewan to Texas — while the Republican Party has been taken over by a hurricane of science denial. Our destabilized climate system, supercharged with billions of tons of manmade global warming pollution, is unlike anything in the historical record. “Welcome to the Land of 10,000 Weather Extremes,” Minnesota meteorologist Paul Douglas gasped. 
“The storm is huge,” Peter Kimbell, emergency preparedness meteorologist for Environment Canada, said. “Much of North America is being affected by this storm. It’s covering millions of square kilometers.” 
Douglas found intensity of the “weather bomb” something “hard to fathom”:
“Yesterday a rapidly intensifying storm, a ‘bomb,’ spun up directly over the MN Arrowhead, around mid afternoon a central pressure of 953 millibars was observed near Orr. That’s 28.14″ of mercury. Bigfork, MN, reported 955 mb, about 28.22″ of mercury. The final (official) number may be closer to 28.20-28.22″, but at some point the number becomes academic. What is pretty much certain is that Tuesday’s incredible storm marks a new record for the lowest atmospheric pressure ever observed over the continental USA. That’s a lower air pressure than most hurricanes, which is hard to fathom.”
The storm front — also dubbed the “Chiclone” for the bizarreness of having a cyclone-like system over Chicago — drew its power from a sharp temperature contrast between record warmth in the southeastern United States and average cold in the north. Thus this record stormfront, though it exhibited hurricane-like power, is unlike actual hurricanes that derive their power directly from heat trapped in the ocean. 
In an exclusive interview with the Wonk Room, Douglas — a nationally renowned meteorologist from Minnesota — discussed this “unprecedented, historic storm” and the consequences for our nation of our artificially altered climate. “We have to get acclimated mentally and physically for this kind of world where these kinds of supercharged storms are more frequent,” he said, as the atmosphere continues to warm. When asked about the numerous conservative global warming deniers in his own state — gubernatorial candidate Tom Emmer, incumbent Rep. Michele Bachmann (R-MN), Congressional candidates Chip Cravaack and Randy Demmer— and across the nation, Douglas said he was “ashamed” of the Grand Old Party for ignoring the “writing on the wall”:
“I’m a recovering Republican, and I don’t recognize my party any more. I’m ashamed so many Republicans don’t recognize the science. The writing is on the wall.”
When asked if reducing global warming pollution is a moral challenge and not just an economic debate, he agreed strongly:
“My dad was the biggest Republican that ever walked the earth. He always said: “Actions have consequences.” To pretend that a 38% increase in greenhouse gases isn’t going to have any impact, that we can have our cake and eat it too, and smear it all over our face, and maybe have our grandchildren deal with the hangover, I think it is immoral.”
Douglas said that this election has “been corrupted with money,” as the “energy lobby is obviously well-funded and powerful, and nobody wants to make waves.”
Nobody wants to make waves — except of course this superstorm, which, as Masters noted, was stronger than “the famed storm that sank the ore carrier Edmund Fitzgerald in 1974, killing all 29 sailors aboard.”

Here are two posts on the connection between human-caused global warming and superstorms that have been devastating the nation and the world during what is likely to be the hottest year on record:
“Given the association of extreme weather and climate events with rising global temperature, the expectation of new record high temperatures in 2012 also suggests that the frequency and magnitude of extreme events could reach a high level in 2012. Extreme events include not only high temperatures, but also indirect effects of a warming atmosphere including the impact of higher temperature on extreme rainfall and droughts. The greater water vapor content of a warmer atmosphere allows larger rainfall anomalies and provides the fuel for stronger storms driven by latent heat.”
“I find it systematically tends to get underplayed and it often gets underplayed by my fellow scientists. Because one of the opening statements, which I’m sure you’ve probably heard is “Well you can’t attribute a single event to climate change.” But there is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms, and it’s unfortunate that the public is not associating these with the fact that this is one manifestation of climate change. And the prospects are that these kinds of things will only get bigger and worse in the future.”
The past 12 months have been the hottest on record, according to NASA.  So perhaps it isn’t completely surprising that we are seeing these record-smashing deluges.  But the number of these beyond-extreme events just in the United States alone ought to make people take notice:
And, of course, another part of the world has been even more devastated by deluges and flooding, albeit while receiving only moderate attention in this country (see Juan Cole: The media’s failure to cover “the great Pakistani deluge” is “itself a security threat” to America).

And then there was the devastation to Russia, a country that always thought it was going to benefit from climate change:
This is all one big coincidence for the anti-science disinformers.  But for the rest of us, the really scary part is that we’ve only warmed about a degree Fahrenheit in the past half-century.  We are on track to warm nearly 10 times that this century (see M.I.T. doubles its 2095 warming projection to 10 °F — with 866 ppm and Arctic warming of 20 °F ).

In short, we ain’t seen nothing yet!

Link:  http://climateprogress.org/2010/10/27/strongest-storm-ever-recorded-in-the-midwest/#comment-303331

Written by fatih al-farahat in ,


BBC: UK rail network 'at risk' from climate change-caused extreme precipitation


UK rail network 'at risk' from climate change

by Howard Falcon-Lang, BBC, October 21, 2010Science reporter
Rail engineers inspect a damaged rail line (Image: RGS)The study warns that the UK rail network faces an increased risk of damage in the future
Changes to the climate could pose a "serious threat" to the UK rail network, scientists have warned.
Extreme weather events - wet winters and hot summers - are projected to become more common over the next 50 years as a result of global warming.
A new study, in the Quarterly Journal of Engineering Geology and Hydrogeology, predicts this could lead to more landslides and floods.
The authors say the damage could cause "widespread disruption" to travel.
To reach their conclusions, scientists from the University of Southampton and Network Rail studied the number of landslides and floods that resulted in delays of more than eight hours to rail travel.

Related stories

They found that the frequency of these major incidents was far higher during the wet winter of 2000-2001, when rail passengers experienced widespread travel disruption.
Scientists predict that such wet winters will become more common in the future, raising fears that climate change could result in "travel chaos".
Lead author Fleur Loveridge, a PhD student at the University of Southampton, said: "This is a really serious issue which needs to be addressed."
She added one of the most "at risk" areas was the south-east of England, because much of London's rail network is built on soft clay, which is particularly prone to landslides.
In a separate study by Network Rail, engineers concluded that half of the UK's 10,000km (6,000 miles) of railway cuttings and embankments were in "poor" or "marginal" condition, leaving them vulnerable to extreme weather events.
Earlier this year, eight people were injured when a train was derailed between Glasgow and Oban as a result of a landslide following heavy rain. In another recent incident, 40 tonnes of rock blocked a Dorset railway line resulting in major delays.
Ms Loveridge told BBC News: "Climate change in the near future is 'locked in' - it's too late to change that.
"We need to raise awareness and increase maintenance budgets, as well as supporting research to develop innovative engineering solutions to tackle the problems before they happen.
"Proactive planning for climate change adaption offers much better value for the taxpayer than bearing the huge costs when things go wrong."
The UK government, in its Spending Review, announced that Network Rail would receive £14bn to support rail maintenance and investment.

Written by fatih al-farahat in


Soaring cotton prices put pressure on inflation

Soaring cotton prices put pressure on inflation


The Independent, September 14, 2010
Soaring cotton prices threaten to put further pressure on inflation amid a chorus of warnings over the likely impact on price tags.
Devastating floods in Pakistan -- one of the world's largest producers -- and fears over this year's crop in China have sent cotton prices surging to 15-year highs in recent weeks.

High street fashion giants Primark, Next and Debenhams have flagged cost pressures as tightening global supplies threaten to push up prices.

The cotton crisis comes at a bad time for retailers, who are already battling against a range of factors, such as higher freight costs, wage inflation in China and the impending VAT hike to 20% in January.
Retail experts at Verdict Research are forecasting that clothing inflation will hit 4.4% in the UK this year -- the highest level for 24 years.
And Next sent shivers through the sector when it said last month that prices may rise by as much as 8% in 2011, with budget retailer Primark adding to the woes by cautioning over profit margins in the face of higher cotton costs.
The latest figures show that cotton prices are up 54% year-on-year, with the floods in Pakistan seeing supply fall far short of demand.
India -- another major producer, alongside China, Pakistan and the United States -- has compounded concerns after its textile industry called for an export ban until next year to ease supply issues.
There had been predictions of a bumper cotton crop from India this year, but reports now suggest heavy rain in both India and China could leave levels short of expectations.
Higher cotton prices have a huge bearing on the cost of clothing, with fabric accounting for around 60% to 70% of product price.
Debenhams said high cotton costs are likely to impact those at the value end of the market most and hopes to be able to absorb much of the price rises.
Primark remained tight-lipped on whether it would increase prices, but its caution over margins suggests the group is planning to take a significant hit to maintain its cut-price reputation.
Neil Saunders, consulting director at Verdict, said most will have little choice but to increase the cost to consumers.
"It means ultimately we will end up paying more for our clothes," he said.
There are fears the recent inflation pressures will mark the end of cheap clothing, such as £8 Primark tops and £2 t-shirts.
But Mr Saunders added that the budget retailers may be able to hold off price hikes by driving large volumes of sales.
"Retailers who will struggle to grow volumes will have to take a hit on profits or put up prices -- that means those in the middle market, such as Next, Bhs and Marks & Spencer," he said.
Verdict has pencilled in sharp clothing inflation next year as well, at 3.6% in 2011, as it believes retailers will spread the impact of the higher input costs and VAT increase over two years.
The British Retail Consortium (BRC) is less fearful over the impact of cotton prices, given its cyclical nature. "There's no reason that this will be a one way trend. Also, UK retailers are highly competitive and one of the factors they compete heavily on is price," said a BRC spokesman.
Clothing price rises must also be put in context, with the recent inflation spike coming after 10 years of sharp deflation.
The cost of clothes in the UK fell by around 2.6% each year between 1998 and 2008, according to Verdict, but it said deflation came to an end last year when prices edged up by 0.3%.
"The increases we're seeing now are partly just an unwinding of those falls," said Mr Saunders.
Link:  http://www.independent.co.uk/news/business/news/soaring-cotton-prices-put-pressure-on-inflation-2078855.html

Written by fatih al-farahat in


Canadian wild rice production wiped out two years running by excessive rain in Manitoba

Wild rice crops wiped out by high water

CBC News, September 14, 2010

A Manitoba wild rice processor is calling this the worst harvest he's seen in more than 50 years.

Harry Arseniuk, who owns the Indian Head rice processing plant in Lac du Bonnet, said a rainy summer and high water levels have decimated Manitoba's wild rice crop.

Usually his plant is in full swing in early September, drying and processing wild rice harvested from Manitoba lakes.

But this year rice pickers have nothing to collect, he said.

"It's just terrible. I've got the processing plant here and I'm sitting here and not one kernel of rice here. Nobody's coming in with any," said Arseniuk, 87.

Manitoba Conservation confirms that high water levels on provincial lakes have drowned out most of the crop.

Arseniuk expects he'll take a big loss this year and worries he won't be able to cover his plant's expenses.

He'd like to sell his business and retire but this is the second consecutive bad year for wild rice and he can't find a buyer.

Read more: http://www.cbc.ca/canada/manitoba/story/2010/09/14/mb-wild-rice-crops-manitoba.html#ixzz0zWQyy2t9

Written by fatih al-farahat in ,


Tomgram: Juan Cole, The Media as a Security Threat to America

Tomgram: Juan Cole, The Media as a Security Threat to America
 
by Juan Cole, TomDispatch, September 9, 2010
 
Call it strange or call it symptomatic.  These last weeks, Afghan War commander General David Petraeus has been on a “media blitz.”  He’s been giving out interviews as if they were party favors.  Yet, as far as I can tell, not a single interviewer has asked him anything like: “General Petraeus, twenty percent of Pakistan, which supposedly harbors Osama bin Laden and various militant groups involved in the Afghan War, and whose intelligence agency reportedly has an ongoing stake in the Afghan Taliban, is now underwater.  Roads, bridges, railway lines, and so U.S. supply lines have been swept away.  How do you expect this cataclysm to affect the Afghan War in the short and long term?”

In these last weeks, the Afghan War has once again been front-page news.  Yet only a single reporter -- the heroic Carlotta Gall of the New York Times -- has thought to focus on the subject of how the Biblical-style floods in Pakistan might affect the U.S. war effort and the overstretched supply lines that play a major role in supporting U.S. troops there.  While you could learn about rising violence in Afghanistan, the perilous state of the Kabul Bank, and many other subjects, reporting on the floods and the war has been nil, with even speculative pieces on the subject largely nonexistent.

We know next to nothing about how U.S. supplies are now getting to Afghanistan, or how much the cost of getting them there has risen, or how this might affect U.S. operations in that country.  Given the scale of the catastrophe and the degree to which the U.S. is embedded in the region, you might at least expect the American media to be flooded with commentary on what the event could mean for us.  Think again.  As Juan Cole (who runs Informed Comment, which offers the best running commentary available on the Middle East and whose most recent book is Engaging the Muslim World) indicates, this startling journalistic blank spot is just a modest part of a far larger blankness when it comes to one of the truly horrific weather events in modern memory.  Don't miss Cole discussing flooded Pakistan on the latest TomCast audio interview by clicking here or, to download it to your iPod, here.  Tom
The Great Pakistani Deluge Never Happened Don’t Tune In, It’s Not Important 
By Juan Cole
The Great Deluge in Pakistan passed almost unnoticed in the United States despite President Obama’s repeated assertions that the country is central to American security.  Now, with new evacuations and flooding afflicting Sindh Province and the long-term crisis only beginning in Pakistan, it has washed almost completely off American television and out of popular consciousness.
Don’t think we haven’t been here before.  In the late 1990s, the American mass media could seldom be bothered to report on the growing threat of al-Qaeda.  In 2002, it slavishly parroted White House propaganda about Iraq, helping prepare the way for a senseless war.  No one yet knows just what kind of long-term instability the Pakistani floods are likely to create, but count on one thing: the implications for the United States are likely to be significant and by the time anyone here pays much attention, it will already be too late.
Few Americans were shown -- by the media conglomerates of their choice -- the heartbreaking scenes of eight million Pakistanis displaced into tent cities, of the submerging of a string of mid-sized cities (each nearly the size of New Orleans), of vast areas of crops ruined, of infrastructure swept away, damaged, or devastated at an almost unimaginable level, of futures destroyed, and opportunistic Taliban bombings continuing.  The boiling disgust of the Pakistani public with the incompetence, insouciance, and cupidity of their corrupt ruling class is little appreciated. 

The likely tie-in of these floods (of a sort no one in Pakistan had ever experienced) with global warming was seldom mentioned.  Unlike, say, BBC Radio, corporate television did not tell the small stories -- of, for instance, the female sharecropper who typically has no rights to the now-flooded land on which she grew now-ruined crops thanks to a loan from an estate-owner, and who is now penniless, deeply in debt, and perhaps permanently excluded from the land.  That one of the biggest stories of the past decade could have been mostly blown off by television news and studiously ignored by the American public is a further demonstration that there is something profoundly wrong with corporate news-for-profit.  (The print press was better at covering the crisis, as was publically-supported radio, including the BBC and National Public Radio.)

In his speech on the withdrawal of designated combat units from Iraq last week, Barack Obama put Pakistan front and center in American security doctrine, “But we must never lose sight of what’s at stake. As we speak, al-Qaeda continues to plot against us, and its leadership remains anchored in the border regions of Afghanistan and Pakistan.”  Even if Pakistan were not a major non-NATO ally of the United States, it is the world’s sixth most populous country and the 44th largest economy, according to the World Bank.  The flooding witnessed in the Indus Valley is unprecedented in the country’s modern history and was caused by a combination of increasingly warm ocean water and a mysterious blockage of the jet stream, which drew warm, water-laden air north to Pakistan, over which it burst in sheets of raging liquid.  If the floods that followed prove a harbinger of things to come, then they are a milestone in our experience of global warming, a big story in its own right.


More here:  http://www.tomdispatch.com/post/175292/tomgram:_juan_cole,_the_media_as_a_security_threat_to_america__/

Written by fatih al-farahat in ,


"Heavy snowfall in a warming world" by Dr. Jeff Masters in his Wunderblog

Dr. Jeff Masters' WunderBlog 



 by JeffMasters,  February 8, 2010

A major new winter storm is headed east over the U.S., today, and threatens to dump a foot or more of snow on Philadelphia, New York City, and surrounding regions Tuesday and Wednesday. Philadelphia is still digging out from its second top-ten snowstorm of recorded history to hit the city this winter, and the streets are going to begin looking like canyons if this week's snowstorm adds a significant amount of snow to the incredible 28.5" that fell during "Snowmageddon" last Friday and Saturday. Philadelphia has had two snowstorms exceeding 23" this winter. According to the National Climatic Data Center, the return period for a 22+ inch snow storm is once every 100 years -- and we've had two 100-year snow storms in Philadelphia this winter. It is true that if the winter pattern of jet stream location, sea surface temperatures, etc., are suitable for a 100-year storm to form, this will increase the chances of a second such storm occurring that same year, and thus the odds of having two 100-year storms the same year are not 1 in 10,000. Still, the two huge snowstorms this winter in the Mid-Atlantic are definitely a very rare event one should see only once every few hundred years and is something that has not occurred since modern records began in 1870. The situation is similar for Baltimore and Washington, DC. According to the National Climatic Data Center, the expected return period in the Washington, DC/Baltimore region for snowstorms with more than 16 inches of snow is about once every 25 years. This one-two punch of two major Nor'easters in one winter with 16+ inches of snow is unprecedented in the historical record for the region, which goes back to the late 1800s.


Figure 1. Cars buried in Philadelphia by "Snowmageddon." Image credit: wunderphotographer TragicHipster.

Top 9 snowstorms on record for Philadelphia:

1. 30.7", Jan 7-8, 1996
2. 28.5", Feb 5-6, 2010 (Snowmageddon)
3. 23.2", Dec 19-20, 2009 (Snowpocalypse)
4. 21.3", Feb 11-12, 1983
5. 21.0", Dec 25-26, 1909
6. 19.4", Apr 3-4, 1915
7. 18.9", Feb 12-14, 1899
8. 16.7", Jan 22-24, 1935
9. 15.1", Feb 28-Mar 1, 1941

The top 10 snowstorms on record for Baltimore:

1. 28.2", Feb 15-18, 2003
2. 26.5", Jan 27-29, 1922
3. 24.8", Feb 5-6, 2010 (Snowmageddon)
4. 22.8", Feb 11-12, 1983
5. 22.5", Jan 7-8, 1996
6. 22.0", Mar 29-30, 1942
7. 21.4", Feb 11-14, 1899
8. 21.0", Dec 19-20, 2009 (Snowpocalypse)
9. 20.0", Feb 18-19, 1979
10. 16.0", Mar 15-18, 1892

The top 10 snowstorms on record for Washington, DC:

1. 28.0", Jan 27-28, 1922
2. 20.5", Feb 11-13, 1899
3. 18.7", Feb 18-19, 1979
4. 17.8" Feb 5-6, 2010 (Snowmageddon)
5. 17.1", Jan 6-8, 1996
6. 16.7", Feb 15-18, 2003
7. 16.6", Feb 11-12, 1983
8. 16.4", Dec 19-20, 2009 (Snowpocalypse)
9. 14.4", Feb 15-16, 1958
10. 14.4", Feb 7, 1936

Heavy snow events--a contradiction to global warming theory?
Global warming skeptics regularly have a field day whenever a record snow storm pounds the U.S., claiming that such events are inconsistent with a globe that is warming. If the globe is warming, there should, on average, be fewer days when it snows, and thus fewer snow storms. However, it is possible that if climate change is simultaneously causing an increase in the ratio of "snowstorms with very heavy snow" to "storms with ordinary amounts of snow", we could actually see an increase in very heavy snowstorms in some portions of the world. There is evidence that this is happening for winter storms in the Northeast U.S. -- the mighty Nor'easters like the "Snowmageddon" storm of February 5-6, 2010, and "Snowpocalypse" of December 19, 2009. Let's take a look at the evidence. There are two requirements for a record snow storm:

(1) A near-record amount of moisture in the air (or a very slow moving storm).
(2) Temperatures cold enough for snow.

It's not hard at all to get temperatures cold enough for snow in a world experiencing global warming. 

According to the 2007 Intergovernmental Panel on Climate Change (IPCC) report, the globe warmed 0.74 °C (1.3 °F) over the past 100 years. There will still be colder than average winters in a world that is experiencing warming, with plenty of opportunities for snow. The more difficult ingredient for producing a record snowstorm is the requirement of near-record levels of moisture. Global warming theory predicts that global precipitation will increase, and that heavy precipitation events -- the ones most likely to cause flash flooding -- will also increase. This occurs because as the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 Intergovernmental Panel on Climate Change (IPCC) report, water vapor in the global atmosphere has increased by about 5% over the 20th century and 4% since 1970. This extra moisture in the air will tend to produce heavier snowstorms, assuming it is cold enough to snow. Groisman et al. (2004) found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events in the U.S. over the past 100 years, though mainly in spring and summer. However, the authors did find a significant increase in winter heavy precipitation events have occurred in the Northeast U.S. This was echoed by Changnon et al. (2006), who found, "The temporal distribution of snowstorms exhibited wide fluctuations during 1901-2000, with downward 100-yr trends in the lower Midwest, South, and West Coast. Upward trends occurred in the upper Midwest, East, and Northeast, and the national trend for 1901-2000 was upward, corresponding to trends in strong cyclonic activity."

The strongest cold-season storms are likely to become stronger and more frequent for the U.S.
The U.S. Global Change Research Program (USGCRP) began as a presidential initiative in 1989 and was mandated by Congress in the Global Change Research Act of 1990 (P.L. 101-606), which called for "a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change." This program has put out some excellent peer-reviewed science on climate change that, in my view, is as authoritative as the U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC) reports. In 2009, the USGCRP put out its excellent U.S. Climate Impacts Report, summarizing the observed and forecast impacts of climate change on the U.S. The report's main conclusion about cold season storms was "Cold-season storm tracks are shifting northward and the strongest storms are likely to become stronger and more frequent."

The report's more detailed analysis: "Large-scale storm systems are the dominant weather phenomenon during the cold season in the United States. Although the analysis of these storms is complicated by a relatively short length of most observational records and by the highly variable nature of strong storms, some clear patterns have emerged (Kunkel et al., 2008).

Storm tracks have shifted northward over the last 50 years as evidenced by a decrease in the frequency of storms in mid-latitude areas of the Northern Hemisphere, while high-latitude activity has increased. There is also evidence of an increase in the intensity of storms in both the mid- and high-latitude areas of the Northern Hemisphere, with greater confidence in the increases occurring in high latitudes (Kunkel et al., 2008). The northward shift is projected to continue, and strong cold season storms are likely to become stronger and more frequent, with greater wind speeds and more extreme wave heights." The study also noted that we should expect an increase in lake-effect snowstorms over the next few decades. Lake-effect snow is produced by the strong flow of cold air across large areas of relatively warmer ice-free water. The report says, "As the climate has warmed, ice coverage on the Great Lakes has fallen. The maximum seasonal coverage of Great Lakes ice decreased at a rate of 8.4% per decade from 1973 through 2008, amounting to a roughly 30% decrease in ice coverage. This has created conditions conducive to greater evaporation of moisture and thus heavier snowstorms. Among recent extreme lake-effect snow events was a February 2007, 10-day storm total of over 10 feet of snow in western New York state. Climate models suggest that lake-effect snowfalls are likely to increase over the next few decades. In the longer term, lake-effect snows are likely to decrease as temperatures continue to rise, with the precipitation then falling as rain."

Commentary
Of course, both climate change contrarians and climate change scientists agree that no single weather event can be blamed on climate change. However, one can "load the dice" in favor of events that used to be rare -- or unheard of -- if the climate is changing to a new state. It is quite possible that the dice have been loaded in favor of more intense Nor'easters for the U.S. Mid-Atlantic and Northeast, thanks to the higher levels of moisture present in the air due to warmer global temperatures. It's worth mentioning that heavy snow storms should be getting increasingly rare for the extreme southern portion of the U.S. in coming decades. There's almost always high amounts of moisture available for a potential heavy snow in the South -- just not enough cold air. With freezing temperatures expected to decrease and the jet stream and associated storm track expected to move northward, the extreme southern portion of the U.S. should see a reduction in both heavy and ordinary snow storms in the coming decades.

The CapitalClimate blog has a nice perspective on "Snowmageddon," and Joe Romm of climateprogress.org has some interesting things to say about snowstorms in a warming climate.

References
Changnon, S. A., D. Changnon, and T. R. Karl. 2006. Temporal and spatial characteristics of snowstorms in the contiguous United States, J. Appl. Meteor. Climatol., 45, 1141-1155.

Groisman, P. Y., R. W. Knight, T. R. Karl, D. R. Easterling, B. Sun, and J. H. Lawrimore. 2004. Contemporary changes of the hydrological cycle over the contiguous United States: Trends derived from in situ observations, J. Hydrometeor., 5, 64-85.

Kunkel, K. E., P. D. Bromirski, H. E. Brooks, T. Cavazos, A. V. Douglas, D. R. Easterling, K. A. Emanuel, P. Ya. Groisman, G. J. Holland, T. R. Knutson, J. P. Kossin, P. D. Komar, D. H. Levinson, and R. L. Smith. 2008. Observed changes in weather and climate extremes. In Weather and Climate Extremes in a Changing Climate: Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands [T. R. Karl, G.A. Meehl, C.D. Miller, S.J. Hassol, A.M. Waple and W.L. Murray (eds.)]. Synthesis and Assessment Product 3.3. U.S. Climate Change Science Program, Washington, DC, pp. 35-80.

Link:  http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1427

Written by fatih al-farahat in ,


M. Sugiyama et al., PNAS 2009, Precipitation extreme changes exceeding moisture content increases in MIROC and IPCC climate models

Proceedings of the National Academy of Sciences, published online before print December 22, 2009; doi: 10.1073/pnas.0903186107

Precipitation extreme changes exceeding moisture content increases in MIROC and IPCC climate models

Masahiro Sugiyami* (Integrated Research System for Sustainability Science and Transdisciplinary Initiative for Global Sustainability, University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan),  Hideo Shiogama (National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan) and Seita Emori (National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506; and Center for Climate System Research, University of Tokyo, Kashiwa-shi, Chiba 277-8568, Japan )

Edited by Kerry A. Emanuel, Massachusetts Institute of Technology, Cambridge, MA, and approved November 24, 2009 (received for review March 23, 2009)

Abstract

Precipitation extreme changes are often assumed to scale with, or are constrained by, the change in atmospheric moisture content. Studies have generally confirmed the scaling based on moisture content for the midlatitudes but identified deviations for the tropics. In fact half of the twelve selected Intergovernmental Panel on Climate Change (IPCC) models exhibit increases faster than the climatological-mean precipitable water change for high percentiles of tropical daily precipitation, albeit with significant intermodel scatter. Decomposition of the precipitation extreme changes reveals that the variations among models can be attributed primarily to the differences in the upward velocity. Both the amplitude and vertical profile of vertical motion are found to affect precipitation extremes. A recently proposed scaling that incorporates these dynamical effects can capture the basic features of precipitation changes in both the tropics and midlatitudes. In particular, the increases in tropical precipitation extremes significantly exceed the precipitable water change in Model for Interdisciplinary Research on Climate (MIROC), a coupled general circulation model with the highest resolution among IPCC climate models whose precipitation characteristics have been shown to reasonably match those of observations. The expected intensification of tropical disturbances points to the possibility of precipitation extreme increases beyond the moisture content increase as is found in MIROC and some of IPCC models.

*Correspondence e-mail:   masahiro_sugiyama@alum.mit.edu

Link to abstract:  http://www.pnas.org/content/early/2009/12/21/0903186107.abstract