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The percent of contiguous U.S. land area experiencing exceptional drought in July reached the highest levels in the history of the U.S. Drought Monitor, said an official at the National Drought Mitigation Center at the University of Nebraska-Lincoln.
Nearly 12 percent of the contiguous United States fell into the "exceptional" classification during the month, peaking at 11.96 percent on July 12. That level of exceptional drought had never before been seen in the monitor's 12-year history, said Brian Fuchs, UNL assistant geoscientist and climatologist at the NDMC.
The monitor uses a ranking system that begins at D0 (abnormal dryness) and moves through D1 (moderate drought), D2 (severe drought), D3 (extreme drought) and D4 (exceptional drought). Exceptional drought's impacts include widespread crop and pasture losses, as well as shortages of water in reservoirs, streams and wells, creating water emergencies.
Eighteen percent of the country is classified as under either extreme or exceptional drought, Fuchs said. Much of it remains contained in the south, particularly Texas, where the entire state is experiencing drought -- three-fourths of it exceptional.
The most recent drought monitor report, released late last week, indicated that 59 percent of the United States was drought-free, while 41 percent faced some form of abnormal dryness or drought. Two weeks ago, 64 percent of the country was drought-free.
Other states that are at least 85 percent abnormally dry or in drought according to the report include:
* New Mexico (100 percent abnormally dry or in drought, 48 percent exceptional)
* Louisiana (100 percent abnormally dry or in drought, 33 percent exceptional)
* Oklahoma (100 percent abnormally dry or in drought, 52 percent exceptional)
* South Carolina (97 percent abnormally dry or in drought, 16 percent extreme to exceptional)
* Georgia (95 percent abnormally dry or in drought, 68 percent extreme to exceptional)
* Arkansas (96 percent abnormally dry or in drought, 6 percent extreme to exceptional)
* Florida (89 percent abnormally dry or in drought, 20 percent extreme to exceptional)
In the next two to three weeks, some affected areas may see some improvement. The wake of Tropical Storm Don should result in rainfall in the central and western Gulf Coast states, but the degree of drought relief will depend upon the storm's intensity, as well as its track and speed.
"Whenever there is a lot of moisture in a short period of time, the potential exists for rapid improvement," Fuchs said. "But while that possibility exists, it won't necessarily mean the end of drought in those areas. It will likely only improve by one drought category for those areas not impacted by any tropical storms or where drought related impacts improve."
The drought monitor combines numeric measures of drought and experts' best judgment into a weekly map. It is produced by the NDMC, the U.S. Department of Agriculture and the National Oceanic and Atmospheric Administration and incorporates review from 300 climatologists, extension agents and others across the nation. Each week the previous map is revised based on rain, snow and other events, observers' reports of how drought is affecting crops, wildlife and other indicators.
To examine current and archived national, regional and state-by-state drought maps and conditions, go to http://droughtmonitor.unl.edu.
Contact: Brian Fuchs, National Drought Mitigation Center climatologist, (402) 472-6775
Writer: Steve Smith, University Communications, (402) 472-4226
Objectivity through automation of new high-resolution inputs and a growing network of unified state or regional recommendations were two main themes of the U.S. Drought Monitor Forum, April 13-14, 2011, at George Mason University in Fairfax, Virginia. Both of these are consistent with the Drought Monitor’s long-term progress toward ever-finer spatial resolution.
David Miskus, a U.S. Drought Monitor (USDM) author at NOAA’s Climate Prediction Center (CPC) and one of the organizers of the Forum, gave a live demonstration of new uses of GIS scripting that will enable the authors to overlay a variety of drought monitoring products. The initial idea of overlaying input products on the USDM’s GIS map was conceived by Eric Luebehusen, a USDM author from the U.S. Department of Agriculture, with scripting help from colleague Brian Morris. In the latest ArcMap (version 10), new scripting capabilities allow for even more automation and short-cuts. “It’s more objective because you’ve got the data right there and you don’t have to eyeball it back and forth,” Miskus said. “You can see where your data products line up and then make your decision. And, these GIS scripts are portable so all USDM authors can eventually utilize them, which in turn would create more consistency on how the USDM was made by each author.”
Less manual work allows the author to spend more time making finer-scale spatial decisions, he noted.
Also on the automation front, author Matthew Rosencrans, CPC, demonstrated an objective Drought Monitor prototype based on the gridded Standardized Precipitation Index which Miskus said seemed fairly promising.
On the human side, authors are benefitting from unified recommendations on drought status that are coming out of Florida, Arizona, North Carolina, the Upper Colorado River Basin and other areas, Miskus said. State or river basin teams with expertise in climatology, hydrology, agriculture, power and other sectors affected by drought convene each week to agree on a recommendation for how the Drought Monitor should depict drought in their area. As an author, Miskus said, “You can take it or leave it, but their facts are usually pretty convincing.”
Another development that may soon be visible to users of the Drought Monitor will be using an S or L over areas to specify short-term or long-term drought, instead of A for agricultural and H for hydrologic. “That way it’s more encompassing,” Miskus said. “Short-term will not be strictly limited to agriculture. In the winter in the Midwest, you may have short-term dryness with no agricultural impacts.” Instead, an area in short-term drought could experience ecological or recreational impacts.
The U.S. Drought Monitor became operational in 1999 as a partnership between federal agencies and academic institutions, including the National Drought Mitigation Center at the University of Nebraska-Lincoln, with the National Oceanic and Atmospheric Administration and the U.S. Department of Agriculture as the lead federal agencies. Since then the USDA and the Internal Revenue Service have started using it to allocate drought relief.
The Drought Monitor, online at http://drought.unl.edu/dm/monitor.html, is produced each week by a team of rotating authors and about 300 reviewers across the United States. The Monitor is a composite index, with authors relying on many different ways of monitoring drought to arrive at the depiction on the map, which is released every Thursday morning. The U.S. Drought Monitor Forum, held every two years, alternates with the North American Drought Monitor Forum. The Forum gives the authors and stakeholders a chance to meet to refine the product and the processes that go into it.
Please check the July edition of DroughtScape for details on where the collection of 2011 U.S. Drought Monitor Forum presentations will be posted.
In 2010 the National Drought Mitigation Center announced several improvements to the U.S. Drought Monitor Archive. In addition to an improved interface, the archive now includes dynamic time series charts, customizable animations and access to the drought narrative archive. Explore the enhancements on the Maps, Tables and Animation pages. For more detailed analyses, visit the GIS Data page for Google Earth files, shapefiles and Percent Area data files.
"This is part of the U.S. Drought Monitor's continuing evolution. We are responding to feedback from our users in developing these dynamic enhancements," said Mark Svoboda, head of the NDMC's Monitoring Program Area. "Many more exciting features are in the works."
The main archive map page -- http://drought.unl.edu/dm/archive.html -- always shows two maps side-by-side for comparison. The default view now includes a statistical comparison of the two maps. Depending on screen resolution, it may be necessary to scroll down past a new gray menu bar below the maps to see it. A middle button on the menu bar takes users to a time series from 2000 to the present. They can zoom to a time interval by clicking and dragging on the timeline. A table on the right displays a constantly-updating statistical summary of drought status for the point on the timeline where the cursor is. The right-most button on the new gray menu bar takes users to a side-by-side comparison of the text summaries that accompany U.S. Drought Monitor maps.
Users can access animations of drought status from the top gray menu bar and from below the current weekly map. Users choose the time and space scales that interest them, going back four, 12, 24 or 52 weeks, for the state, region, or contiguous United States. Pause and play buttons facilitate analysis.
The U.S. Drought Monitor image archive now includes high resolution grayscale versions of the image archive. Maps are available for the contiguous U.S., the Drought Monitor regions and each state as JPGs, PNGs and PDFs. For more information, contact Brian Fuchs, bfuchs2@unl.edu.
Updated August 5, 2011
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