Thursday, April 28, 2011

U.S. - Storms that spawned deadly tornadoes have flattened buildings and knocked out power lines across the central and southern United States, raising the death toll to at least 56. Forty-five people were killed in Alabama alone, and on Wednesday US President Barack Obama ordered the government to 'move quickly' to get search and rescue aid to the southern state. Earlier, states of emergency were declared in Alabama; Arkansas; Kentucky; Mississippi; Missouri; Tennessee; and Oklahoma.
UPDATE - More than 72 people in four states have been killed by the storms, including at least 15 in Tuscaloosa and 15 in Birmingham, Alabama. ‘We have way over 100 injuries throughout the city of Tuscaloosa. We have hundreds of homes and businesses destroyed and hundreds more damaged.’
Current death toll stands at 58 in Alabama, 11 in Mississippi, two in Georgia and one in Tennessee. The storm system spread destruction on Tuesday night and Wednesday from Texas to Georgia, and it was forecast to hit the Carolinas next and then move further northeast. The threat area on Thursday morning includes eastern Tennessee and Alabama, Georgia, northern Florida and parts of the Carolinas. Severe thunderstorms, damaging wind gusts, hail and isolated tornadoes are all possible. (Amazing photos & video)

**Things ain't what they used to be, and probably never was.**
Will Rogers

This morning -

Yesterday -
4/27/11 -

NEW ZEALAND - Christchurch, New Zealand's second-largest city, faces up to 20 years of rebuilding as a result of the earthquake in February that destroyed one-third of its central business district.

No current tropical storms.


NEW ZEALAND - The army has been called in to help evacuate people from some coastal towns in the Hawkes Bay, after extreme rainfall caused flooding overnight. Near Hastings, the extreme weather caused flooding and slips in three coastal settlements; Waimarama, Clifton and Te Awanga. At least 60 people in Te Awanga and Waimarama have been forced from their homes by rising waters, after 200mm of rain fell in just 24 hours. Roofs have been blown off, trees knocked down and power cut out. Fourteen Hawke's Bay settlements have been hit by flooding and slips, with up to 100 people evacuated in all. Firefighters spent an anxious couple of hours checking houses, making sure people were safe – but many had already self-evacuated.
A number of roads have also been closed. Army personnel have since arrived in the region and have made it through to Waimarama to help with evacuations. It was still raining heavily. "We are at the beginning of the season at the moment, so the soil isn't saturated. We will have some damage, but hopefully it will be more like silt rather than big slips."
Meanwhile, gale force winds are lashing much of the central and lower North Island. Workers in the capital were among those who had a hard time getting to work Wednesday morning, umbrellas rendered useless in the gusts – forecast to reach up to 100kmph. The storm cut power to about 11,500 Powerco customers yesterday. Extremely high winds were making restoration difficult.

A huge tornado levelled parts of the city of Tuscaloosa, in Alabama, killing at least 15, as storms tore through southern states from Texas to Georgia. Eleven more people were killed in storms earlier this week in the South. Governors in Alabama, Arkansas and Tennessee have each declared a state of emergency as a result of the newest round of heavy winds, rains and tornadoes. "While we may not know the extent of the damage for days, we will continue to monitor these severe storms across the country and stand ready to continue to help the people of Alabama and all citizens affected by these storms."
Media reported a tornado near Andrews Air Force Base in Maryland, just outside Washington DC, on Wednesday evening. Parts of Tuscaloosa have been decimated by their tornado. "The city experienced widespread damage from a tornado that cut a path of destruction deep into the heart of the city." A hospital in the city, which has a population of about 83,000, said its emergency room had admitted at least 100 people. The damage from the tornado that struck near Tuscaloosa was made worse by earlier storms, which allowed the new storm system to uproot entire trees out of loose, wet mud. At least 335,000 customers were without power in the region, with more storms on the way. "The number of outages could be as high as what we saw with Hurricane Ivan or Hurricane Katrina." Suspected tornadoes are being blamed for damaged roofs and downed power lines across the South. Mississippi was the site of seven more deaths on Wednesday. Downed trees blocked roads and highways in both Mississippi and Alabama, hindering rescue efforts by emergency responders. Storm systems have pummelled states across the southern US for weeks, with severe weather being blamed for the deaths of 10 people in Arkansas and one in Mississippi earlier this week. (video & photos)
Storms knocked out nuclear units - Severe storms and tornadoes moving through the Southeast dealt a severe blow to the Tennessee Valley Authority on Wednesday, causing three nuclear reactors in Alabama to shut and knocking out 11 high-voltage power lines. All three units at TVA's 3,274-megawatt Browns Ferry nuclear plant in Alabama tripped about 5:30 EDT (2230 GMT) after losing outside power to the plan. The plant's output had reduced power earlier due to transmission line damage from a line of severe storms that spawned a number of tornadoes as it moved through Mississippi, Alabama, Kentucky and Tennessee. Early information indicated the units shut normally and the plant's diesel generators started up to supply power for the plant's safety system. Crews were working to restore service, but more severe weather was forecast.
Most of the damage so far has occurred in the western part of TVA's service territory in Mississippi, Alabama and western Tennessee and Kentucky. Rainfall amounts between four and seven inches have fallen since Tuesday in the area. Eight of the nine dams on the Tennessee River were generating at full power to move water through the river system to help control flooding.


Changes to a "neglected" ocean current near the southern tip of Africa could keep Europe warm even if the Gulf Stream switches off, scientists say. Warm water in the Agulhas Current flows from the Indian Ocean into the Atlantic where it brings changes further north. Researchers say this could compensate if the main northwards flow of heat, carried by the Gulf Stream, drops. This effect has largely been overlooked as a factor affecting climate change.
The Agulhas Current flows southwards down the eastern coast of Africa. When it reaches the continent's southern tip - Cape Agulhas - most of the water swings eastward and back into the Indian Ocean. But some of it forms giant eddies and rings, up to 300km (200 miles) across and extending from the top of the ocean to the bottom, that go in the other direction - rounding the cape and flowing into the Atlantic. This bit is known as the Agulhas Leakage.
Exactly how much water travels in this direction is not known, and is thought to vary markedly from year to year. But this team of scientists say wind shifts further south make it likely that leakage is increasing. "This prediction comes from a [computer] model - the leakage itself is very difficult to measure because it happens over a wide corridor of ocean and because of its eddying nature."
Once in the Atlantic, the warm and salty Agulhas water acts to strengthen the main current system, the Atlantic Meridional Overturning Circulation (AMOC). A weakening Gulf Stream would bring colder weather to the shores of Western Europe Part of this circulation is the Gulf Stream, which brings hot water northwards, keeping parts of Western Europe and eastern North America several degrees Celsius warmer than they would otherwise be.
Thanks largely to the 2004 movie The Day After Tomorrow, the possibility that this would "switch off" in a warmer world is one of the best-known potential climate change impacts, even though there is a lot of uncertainty about whether it will happen. The scientists say an increase in Agulhas Leakage could compensate. "This could mean that current IPCC model predictions for the next century are wrong and there will be no cooling in the North Atlantic to partially offset the effects of global climate change over North America and Europe. Instead, increasing Agulhas Leakage could stabilise the oceanic heat transport carried by the Atlantic overturning circulation." Analysis of sediments shows the Agulhas Leakage has varied hugely in the past, notably at transitions between Ice Ages and the warm periods in between. Its modern behaviour is being studied by satellites and by instruments in the sea; but still, the record is short and much clearly remains to be discovered.
Further north in the Atlantic, the amount of water being carried in the AMOC varies, naturally, by almost a factor of 10; so discerning a long-term trend becomes very difficult.
Better measurements are one aim of scientists in the field, better computer models are another, with existing global models not able to replicate the circular eddies typical of the Agulhas system. In the long term, putting all of this together should lead to much better understanding of how the AMOC behaves - in particular, whether it can shut down stably for long periods, and what that would mean for Europe. "If you think about evaporation over the Atlantic, the ocean is clearly losing water, so the circulation system brings new water in to balance that. There are two pathways - warm, salty water from the Indian Ocean and colder, fresher water from the Drake Passage [between the southern tip of South America and Antarctica]. And there's pretty strong evidence that the balance between those pathways indicates whether or not the Gulf Stream is safe".

The Gulf Stream does not appear to be slowing down, said US scientists in March who have used satellites to monitor tell-tale changes in the height of the sea. Confirming work by other scientists using different methodologies, they found dramatic short-term variability but no longer-term trend.
The stream is a key process in the climate of western Europe, bringing heat northwards from the tropics and keeping countries such as the UK 4-6C warmer than they would otherwise be. It forms part of a larger movement of water, the Atlantic Meridional Overturning Circulation, which is itself one component of the global thermohaline system of currents. Between 2002 and 2009, the team says, there was no trend discernible - just a lot of variability on short timescales. The satellite record going back to 1993 did suggest a small increase in flow, although the researchers cannot be sure it is significant. "The changes we're seeing in overturning strength are probably part of a natural cycle. The slight increase in overturning since 1993 coincides with a decades-long natural pattern of Atlantic heating and cooling."
The first observations suggesting the circulation was slowing down emerged in 2005. Using an array of detectors across the Atlantic and comparing its readings against historical records, scientists suggested the volume of cold water returning southwards could have fallen by as much as 30% in half a century - a significant decline. The surface water sinks in the Arctic and flows back southwards at the bottom of the ocean, driving the circulation. However, later observations by the same team showed that the strength of the flow varied hugely on short timescales - from one season to the next, or even shorter. But they have not found any clear trend since 2004.
The team now has a chain of instruments in place across the Atlantic, making measurements continuously. "In four-and-a-half years of measurement, we have found there is a lot of variability, and we're working to explain it." The quantities of water involved are huge, varying between four million and 35 million tonnes of water per second. The team calculates that their system is good enough to detect a long-term change in flow of about 20% - but it has not happened yet.
Driven by Hollywood, a popular image of a Gulf Stream slowdown shows a sudden catastrophic event driving snowstorms across the temperate lands of western Europe and eastern North America. The scientists say that has always been fantasy - as is the idea that a slow-down would trigger another ice age. "But the Atlantic overturning circulation is still an important player in today's climate. Some have suggested cyclic changes in the overturning may be warming and cooling the whole North Atlantic over the course of several decades and affecting rainfall patterns across the US and Africa, and even the number of hurricanes in the Atlantic."