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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Thanks for pointing that out, only an hour and half from Charleston,SC. Those storms came thru here last nite.
The GFS has a very poleward bias and has been having some trouble forecasting highs and troughs. IMO this won't recurve and at this time it is 50/50 between the carib. and east coast where are future system will head
Under Marine Data here you can go to the John Hopkins Applied Physics Lab site...Click a region and then look at the multi merged to present link at top. For some reason it seems that they stopped archiving data after 2008. Not sure why though.
WUnderful,,not.
Change the address in the address bar. For example
"http://www.aoml.noaa.gov/phod/dataphod1/work/HHP/NEW/2010220at.jpg"
That is for August, 8, 2010. Change the 2010 to 2005 and it is now addressed to August, 8, 2005. To go to a different date change the number after 2010. "220" is August 8. "221" is August 9.
It was quite a show with sideways lightening. I joined WU so I could represent the lowcountry. Definitely a novice but love to study the tropics and learn. WU is the best place to do that imo. Thank you for the welcome.
fxus64 klix 140850
afdlix
Area forecast discussion
National Weather Service New Orleans la
350 am CDT Sat Aug 14 2010
Synopsis...
center of remnants of dew point 5 appear to be between Meridian and
Tuscaloosa this morning. Scattered showers have developed over the
coastal waters and near the coast. Cell movement is to the
northeast at 15 kts...so threat of flash flooding appears to be
minimal in the short term.
&&
Short term...
remnants/upper low will gradually rotate back toward the area
around the east end of the Texas upper ridge...reaching the coast
again near Pensacola Sunday night and moving westward back across
the area Monday and Tuesday. Still seeing significant model
differences in details...especially in wind fields. GFS appears to
have feedback issues...with one effect producing 45 knots winds over
coastal waters...even while surface low remains over land.
European model (ecmwf)/NAM solutions are weaker and generally trended toward these
solutions.
Airmass remains extremely moist and diurnal development of
convection will continue...with 12 hour areal coverage around
50-60 percent next several days. Cell movement today should
prevent widespread heavy rain amounts...so will get rid of Flash Flood
Watch. Expect one may be needed again around Monday or Tuesday as
low returns. Will mention locally heavy rain in daytime periods in
forecast. Temperatures will be much closer to normal due to the
additional clouds and precipitation. 35
&&
Long term...
all models move system west into western Louisiana and Texas
Wednesday...as Florida ridge builds westward toward end of week.
This will allow some drying across the area at the end of the
week...with some warming of temperatures. Probability of precipitation will remain in the
chance daytime range...slight chance at night. 35
&&
Aviation...
very low IFR conditions in fog and stratus will continue through at
least 11z around kmcb...with mainly MVFR conditions elsewhere due to
light br. Prevailing visibilities will improve after 13-14z with mainly VFR
weather expected the remainder of the day. There will be numerous
shra/tsra...some with mainly brief periods of IFR/MVFR...starting in
coastal areas this morning...and gradually spreading inland this
afternoon. 22/dew point
&&
Marine...
west to southwest winds near 15 knots were reported at many of the
marine observations offshore...and these winds are likely to
continue this morning before settling down to 10 to 15 knots this
afternoon. Seas near 3 feet may approach 4 feet in some of the
eastern waters today. An area of weak low pressure over south
central Alabama is expected to drift back south into the southwest
Alabama and western Florida Panhandle region on Sunday.
Going into Monday through the middle of next week...the details of
the forecast will depend on the timing...exact movement...and
strength of the surface low that the models show moving west back
towards the Mississippi and southeast Louisiana coasts on Monday
into Tuesday morning. Have gone close to the GFS for timing...but
closer to the NAM regarding strength. The GFS continues to show
winds near to exceeding gale force...and have backed off
significantly with maximum winds closer to 20 knots late Sunday
night through Tuesday. Even if sustained winds do not get
stronger...it is likely there will be numerous gusts over 30 knots
from scattered to numerous thunderstorms. Conditions will improve by
Wednesday into Thursday as the low pulls away to the west and
northwest. 22/dew point
&&
00z ECMWF develops our system, however, even though it shows a high pressure right on top of the system steering it west. There is a trough depicted that could possibly recurve it, doubt it though.
Looking at the map Drak just posted it is seeming likely this will go w-wnw for the long haul
Heavy rain and Thunder here in Trinidad now.
Looks to be no more than ITCZ stuff.
Maybe a wave, but I have not checked....
Wait, its showing favorable conditions?
Your right, pretty impressive. What's more impressive is that anti-cyclone, stronger systems usually produce one.
I read his blog daily. He's not afraid to go out on limb with his forecast. That's for sure!
There is a good site out of Barbados
www.brohavwx.com
Not sure where to find rainfall potential. Although there is a Weather Radar in T&T but I cannot access it. Will look for the address...
Can you help answer the question at post 1530?
MJO sticking our basin
The Insurance people are a trip...
A friend of mine had a large portion of hillside come through his house.
The Insurer said "Ah! This is a 'LandSlip' and you only have 'LandSlide' insurance" !!!
He took them to court and won.
Link
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