Causes of the Russian heat wave and Pakistani floods
The Great Russian Heat Wave of 2010 is one of the most intense, widespread, and long-lasting heat waves in world history. Only the European heat wave of 2003, which killed 35,000 - 50,000 people, and the incredible North American heat wave of July 1936, which set all-time extreme highest temperature records in fifteen U.S. states, can compare. All of these heat waves were caused by a highly unusual kink in the jet stream that remained locked in place for over a month. The jet stream is an upper-level river of air, between the altitudes of about 30,000 - 40,000 feet (10,000 - 12,000 meters). In July over Europe and Asia, the jet stream has two branches: a strong southern "subtropical" jet that blows across southern Europe, and a weaker "polar" jet that blows across northern Europe. The polar jet stream carries along the extratropical cyclones (lows) that bring the mid-latitudes most of their precipitation. The polar jet stream also acts as the boundary between cold, Arctic air, and warm tropical air. If the polar jet stream shifts to the north of its usual location, areas just to its south will be much hotter and drier than normal. In July 2010, a remarkably strong polar jet stream developed over northern Europe. This jet curved far to the north of Moscow, then plunged southwards towards Pakistan. This allowed hot air to surge northwards over most of European Russia, and prevented rain-bearing low pressure systems from traveling over the region. These rain-bearing low pressure systems passed far to the north of European Russia, then dove unusually far to the south, into northern Pakistan. The heavy rains from these lows combined with Pakistan's usual summer monsoon rains to trigger Pakistan's most devastating floods in history.
Figure 1. Winds of the jet stream at an altitude of 300 millibars (roughly 30,000 feet high). Left: Average July winds from the period 1968 - 1996 show that a two-branch jet stream typically occurs over Europe and Asia--a northern "polar" jet stream, and a more southerly "subtropical" jet stream. Right: the jet stream pattern in July 2010 was highly unusual, with a very strong polar jet looping far to the north of Russia, then diving southwards towards Pakistan. Image credit: NOAA/ESRL.
What caused this unusual jet stream pattern?
The unusual jet stream pattern that led to the 2010 Russian heat wave and Pakistani floods began during the last week of June, and remained locked in place all of July and for the first half of August. Long-lived "blocking" episodes like this are usually caused by unusual sea surface temperature patterns, according to recent research done using climate models. For example, Feudale and Shukla (2010) found that during the summer of 2003, exceptionally high sea surface temperatures of 4°C (7°F) above average over the Mediterranean Sea, combined with unusually warm SSTs in the northern portion of the North Atlantic Ocean near the Arctic, combined to shift the jet stream to the north over Western Europe and create the heat wave of 2003. I expect that the current SST pattern over the ocean regions surrounding Europe played a key role in shifting the jet stream to create the heat wave of 2010. Note that the SST anomaly pattern is quite different this year compared to 2003, which may be why this year's heat wave hit Eastern Europe, and the 2003 heat wave hit Western Europe. Human-caused climate change also may have played a role; using climate models, Stott et al. (2004) found it very likely (>90% chance) that human-caused climate change has at least doubled the risk of severe heat waves like the great 2003 European heat wave.
Figure 2. A comparison of the departure of sea surface temperature (SST) from average just prior the the start of the great European heat waves of 2003 and 2010. Temperatures in the Mediterranean Sea were up to 4°C above average in 2003, which has been implicated as a major cause of the Western European heat wave of 2003. Image credit: NOAA/NESDIS.
References
Feudale, L., and J. Shukla (2010), "Influence of sea surface temperature on the European heat wave of 2003 summer. Part I: an observational study", Climate Dynamics DOI: 10.1007/s00382-010-0788-0
Stott, P.A., Stone, D.A., and M.R. Allen (2004), "Human contribution to the European heatwave of 2003", Nature 432, 610-614 (2 December 2004) | doi:10.1038/nature03089. (Here is a free version of the paper, presented at a conference.)
The World Meteorological Organization (WMO) has posted an analysis of the recent extreme weather events, concluding, "the sequence of current events matches IPCC projections of more frequent and more intense extreme weather events due to global warming."
See also my posts, The Great Russian Heat Wave of 2010: 102°F in Moscow and, Over 15,000 likely dead in Russian heat wave; Asian monsoon floods kill hundreds more.
Moscow sees real relief from the Great Russian Heat Wave of 2010
For the first time in more than a month, temperatures at Moscow's Domodedovo airport failed to exceed 30°C (86°F) today. Clouds and thunderstorms blew into the city this morning, keeping the high temperature down to just 29°C (84°F). This breaks a string of 35 straight days when the temperature reached 30°C. At Moscow's official observing site, the Moscow Observatory, this string was 30 days. Moscow's average high temperature for August 13 is 20°C (68°F), so today's temperatures were still well above normal. However, today's cool-down marks the beginning of the end for Russia's great heat wave. The latest forecast for Moscow calls for high temperatures below 30°C for the coming week, and Moscow may not exceed that threshold for the remainder of summer. Long range forecasts from the ECMWF and GFS models continue to suggest that a series of troughs of low pressure will attack the ridge of high pressure anchored over Russia, bringing cooler temperatures just 5°C (8°F) above average to Russia late next week. By ten days from now, the ECMWF model shows a strong trough of low pressure over Moscow, and a end to the Great Russian Heat Wave of 2010. Moscow still has to concern itself with smoke from the wildfires burning southeast of the city; winds are expected to shift early next week and bring the smoke towards the city again. However, the cooler weather should aid fire-fighting efforts, so the smoke problems should not be as bad as last week's nightmare.
Figure 2. Image from NASA's Aqua satellite of smoke from wildfires burning to the southeast of Moscow yesterday, August 12, 2010. Northerly winds were keeping the smoke from blowing over the city. Image credit: NASA.
The tropics are quiet
The remnants of Tropical Depression Five continue to bring heavy rain to portions of Southeast Louisiana today. Up to five inches of rain has fallen in regions near New Orleans. The GFS model predicts that the remains of TD 5 could move off the coast of Mississippi by the middle of next week and regenerate, but none of the other models is making this forecast. Both the GFS and ECMWF models are predicting that a tropical storm will develop off the coast of Africa by next Friday, August 20.
Donations urgently needed in Pakistan
The devastation wrought by the worst flooding in Pakistan's history requires a huge response by the international community. Wunderblogger Dr. Ricky Rood, author of our Climate Change Blog, has a friend working in Pakistan who underscored the desperate situation there:
This is the worst natural disaster in the history of Pakistan in terms of number of people and area affected. Although not as many people have been killed as in the 2005 earthquake, we have already nearly 900,000 displaced persons thus far just in Khyber Pakhtunkhwa. Crops are destroyed; shops, hotels, and other business have simply been swept away in Swat, which had just this year been cleared of Taliban and was on the way to recovery; and districts closer to Peshawar and parts of Peshawar district are still, or perhaps again after yesterday/today, under water. After the immediate emergency response, it will be years of rebuilding to replace what has been lost and to start to develop again. I know you have the power to control the weather, so if you cold give us a week or two without more rain at least we could keep the helicopters flying and give people a chance to go to their homes, recover what might still be there, set up tents if we can get enough to them, and start to clean up."
She gave the following recommendations for charities that do work in the flood-ravaged zone, and are effective at getting aid to those who need it the most:
Doctors Without Borders
The International Red Cross
MERLIN medical relief charity
The mobile giving service mGive allows one to text the word "SWAT" to 50555. The text will result in a $10 donation to the UN Refugee Agency (UNHCR) Pakistan Flood Relief Effort.
She mentioned that it is better to send money to the organizations doing the relief work than to try to organize shipments of goods.
Jeff Masters
Reader Comments
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Yup, even if the first one turns out, the US will be under threat from the next ones in line given the pattern that is developing. The first one isn't even guaranteed to recurve yet either. the GFS ensemble mean still sticks it into the SE US coast.
yes all of FL is DOOM you ran out of time too get what you need
this mmissing with you lol
Every time a long-range model run comes out for something over or near west Africa or in the eastern Atlantic and has it hitting NC, it seems it never comes true.
Hope that doesn't become true either. Which wave is that model developing? The one about to emerge from Africa now?
What, am I missing something LOL? Not seeing that many precursor systems in the Atlantic right now that could emerge.
00z Euro
i be going too bed soon
72hr
96hr
I see,
But, I don't believe the models yet. After all, I'm seeing tropical waves over Africa, but they don't look that impressive:
http://www.goes.noaa.gov/FULLDISK/GMIR.JPG
These models might see low shear and warm waters, and say, hmmm, I'll just go off of these favorable conditions and develop every wave coming off of Africa.
Is it just me, or are the waves coming off of Africa over the last few weeks not as impressive as the early June waves (Invest 92L in June for example?) What happened to our tropical waves? I thought systems like 92L in June should have been a harbinger of waves in August and September. I am surprised we aren't seeing some of these waves coming off of Africa with "wicked vortexes." The waves that have been coming off are disorganized blobs that lose momentum once they emerge into the Atlantic for the most part.
Vigorous mid-level spin
Not ready to agree with that. Usually La Nina years (and right now we're in a La Nina) mean a westward extension of the Bermuda-Azores ridge, which tends to block systems from coming over the eastern US (take a La Nina year like 1995 or 2007 for example).
I don't, and I take long range runs with a grain of salt, especially if the models are not intelligent and developing every wave coming off of Africa just because of low shear and warm waters.
Okay, that's a better satellite view than I have over Africa. Yeah, that wave (PGI30L) does look pretty good. But, the wave right at the west coast of Africa right now has "poofed-out," you can't even see it in satellite imagery right now (and it had a nice spin earlier). I wonder if this wave (PGI30L) will follow suit and poof-out once its approaches the coast. We'll see.
If your looking for an accurate long-range model, the CMC is your best bet. It's been dominating for a while.
The wave ahead of PGI30L will act as a buffer and get rid of the dry and stable atmosphere off the coast. It was never really supposed to amount to much. The GFS even shows the vorticity from that wave interacting with PGI30L which sparks development. This wave will help PGI30L a lot.
If we have the models consistently developing this like they are for another 48 hours, I'd be very surprised if it didnt develop.
Thanks for the link, but what do you mean by dominating? Does anyone compare the model runs to what actually happens?
LOL, there were some different opinions about the CMC model a couple of weeks ago on this blog (if I remember the time correctly). I remember someone saying CMC stands for "can't model crap." Is CMC good or not, confused.
The CMC received a major upgrade a year or two ago and is MUCH better than it used to be back in 2007. It used to constantly spin cyclones out of every single area of vorticity.
I see what you are saying now. Will keep an eye on PGI30L, couldn't really see the good spin with it with the satellite imagery over Africa that I look at. Where do you guys get better Africa satellite imagery that updates a lot, better than this junk?
I didnt see anyone that actually did that.
I'll I see are people posting models.
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