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Heatwave blisters eastern USA, drought parches southern USA

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20110727 – The National Drought Mitigation Centre at the University of Nebraska at Lincoln has catalogued the consequences, using media reports, government analyses and contributions from the public, said The Economist in its report on the US drought and heatwave. In ‘Drought in the South: Bone-dry – Drought has blanketed nearly a third of the lower 48‘ the weekly said: “There are wildfires in the south-west and water restrictions in the south-east. Fields are scrubby and fallow, and in some counties the ground is riddled with deep cracks. Farmers are struggling to produce crops, and ranchers are worried about watering their cattle. As their losses mount, crop prices have risen.”

Drought-wracked landscape in the southern USA. Photo: The Sydney Morning Herald/Jason South

According to a report from the Texas AgriLife Extension Service, wheat was selling at more than $8 a bushel at the beginning of the summer, compared with an average annual price of $5.25 last year. Still, Texas farmers will bring in only an estimated $274m this year; the average for the past five years was more than twice as high.

Meteorologists say it is impossible to explain fully how these things happen. In 2010 the westward slopping of cooler water across the tropical Pacific, a phenomenon called La Niña, made itself felt on weather around the world. That La Niña is now over, according to scientists, but the patterns of atmospheric circulation that were associated with it are persisting, which could account for some of the drought. There is also the problem of man-made climate change, which is expected to intensify both droughts and floods.

In recent years, the Colorado River has become less reliable, said the Scientific American. Since 1999, abnormally low precipitation totals and hot and dry conditions have brought reservoir water levels close to record lows. The multiyear drought, the most severe since documentation began more than 100 years ago, has put the water supply in the thirsty Southwest in jeopardy.

Graphic: The Economist

This year, heavy snowpack and spring precipitation have brought the region some relief by partially refilling the reservoirs. But while National Oceanic and Atmospheric Administration research shows that snowmelt runoff into the upper basin hasn’t been this high since 1986, the southern end of the Colorado River continues to stop shy of the Sea of Cortez, where it used to run until the late 1990s.

The paradox is that this season stands in such stark contrast to the past 11 years of drought, highlighting the types of variability that climate change can wreak on the hydrological cycle. The Bureau of Reclamation released the first of three interim reports last month as part of its broader Colorado River Basin Water Supply and Demand Study. The report is designed to provide an outlook on the next “highly uncertain” 50 years (until 2060) of the river’s life. Authors wrote that in the nearly quarter-million-square-mile Colorado River Basin, “climate change, record drought, population increases and environmental needs” are likely to make water supplies ever scarcer.

NASA’s Earth Observatory has said that by July 2011, Texas and New Mexico had completed the driest six-month period on record. Average rain between January and June was more than eight inches (203 millimeters) below average in Texas and 3.5 inches (89 millimeters) below average in New Mexico. Record warm temperatures also persisted in Texas between April and June. The lack of rain and the warm temperatures added up to exceptional drought.

This image shows the impact of drought on plants throughout Texas, New Mexico, and Oklahoma. Made with data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite, the image compares plant growth between June 26 and July 11, 2011, with average conditions for the period. The image [left] is dominated by brown, showing that plants were growing less than average throughout Texas and New Mexico. The image supports an assessment by the U.S. Drought Monitor, which states that 94 percent of the range and pastureland in Texas was in poor or very poor condition in June 2011. In Oklahoma, 78 percent of range and pastureland was in poor condition.

Though drought is not a disaster that strikes all at once, it is nonetheless a devastating event that can cause death, disease, and loss of money and property. For these reasons, drought is termed the creeping disaster. So far farmers in Texas have lost 30 percent or more of their crops and pasture in 2011. The loss led the U.S. Department of Agriculture to declare a natural disaster in 213 Texas counties and additional counties in Arkansas, Louisiana, New Mexico, and Oklahoma. The declaration qualifies farmers in these regions for low-interest loans to cover their losses.

20110724 – This temperature chart by state explains the heat gripping southern and eastern USA. The heat wave enveloping the Eastern Seaboard brought punishing record temperatures to the Washington region Friday, sending scores of people to emergency rooms with heat-related illnesses and closing down outdoor events. The combination of heat and humidity produced a heat index in Washington of 121 degrees, the highest since July 1980.

Unhealthy levels of heat and humidity are encompassing much of the eastern half of the US, according to NOAA’s National Weather Service, as a persistent heat wave continues its grip on the central US while expanding into the East. According to NOAA’s National Weather Service, approximately 132 million people in the United States are under a heat alert (Excessive Heat Warning or Watch or Heat Advisory) as of Friday morning.

Temperatures in the 90s to near 100 degrees will feel as hot as 115 degrees or higher when factoring in the high humidity. Record high temperatures are likely to be set in some locations — adding to the more than 1000 records that have been set or tied so far this month.

More than 4000 daily high temperature records were tied or broken in June, mostly east of the Rockies, and there were 159 reports of the record hottest temperature for June and 42 reports of all-time record hottest temperature ever. Drought intensified across parts of the Southwest to Southeast. While the southern Plains’ 1950s drought of record is unsurpassed in terms of duration, the current drought in parts of Texas is more intense than the 1950s drought when measured by the Palmer Hydrological Drought Index. While blanketing the southern U.S. with hot and dry weather, a upper level high pressure system effectively blocked any Gulf of Mexico moisture from feeding into the area. Meanwhile, the upper-level low pressure trough in the Northwest attributed to the cool, wet anomalies in the region.

Right now, the Examiner has said, approximately 29 percent of the country is experiencing some level of drought. About 12 percent of the US is experiencing “exceptional drought”, which is the highest level of drought. The combination of very little rain and scorching heat over much of the nation has been absolutely devastating. Many areas have been dealing with high temperatures in the 90s and the low triple digits for weeks.

The US Drought Monitor has said that the drought conditions across the Southern Great Plains persisted, and worsened across most areas, with localized improvements due to isolated rain events. AHPS precipitation estimates in excess of 5 inches prompted the improvement across southeastern Texas while sparse rainfall just east of El Paso also allowed for minor improvement. The rest of the southern Great Plains experienced continued hot (2 – 8 degrees F above normal) and dry weather.

Exception drought (D4) coverage was expanded in coverage across portions of Texas, including Erath, Hood, Somervell, Comanche, Jim Wells, and Duval counties. Additional expansion and intensification of the less severe drought conditions was included in the latest analysis across central Texas. Range and pastureland across Texas and Oklahoma continued to deteriorate. Across Texas, 94% of the range and pastureland was described as being in poor or very poor condition. This is a record weekly value, although measurement sof this kind only extend back to 1995. Across Oklahoma, 78% of the range and pastureland described as poor or very poor, tied for the fifth highest percentage (August 6, 2006). The rest of August 2006 saw statewide poor and very poor conditions expand to over 80% of all range and pasturelands.

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