TESTIMONY OF
DR. LOUIS UCCELLINI, DIRECTOR
NATIONAL CENTERS FOR ENVIRONMENTAL PREDICTION
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
BEFORE THE
COMMITTEE ON ENERGY AND NATURAL RESOURCES
UNITED STATES SENATE
March 9, 2004
Good morning, Mr. Chairman and members of the Committee. Thank you for inviting me to discuss the ongoing drought in the Western United States. To complement its long-standing water supply forecasting done jointly with the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS), the National Oceanic and Atmospheric Administration (NOAA) has greatly expanded its role in monitoring and forecasting droughts in recent years. I am happy to have the opportunity to talk to you about the current drought situation, its impacts on water supplies, the summer outlook, research, and how NOAA interacts with other agencies to deliver these drought products and related services.
I am Louis Uccellini, Director of the National Centers for Environmental Prediction, which is part of NOAA’s National Weather Service (NWS). Two of our Centers are closely involved with forecasting weather and short-term seasonal and climate variations, namely the Hydrometeorological Prediction Center (HPC) and the Climate Prediction Center (CPC). The latter center is involved with drought monitoring and forecasting, and currently produces the seasonal drought outlooks and continues to play a key role in producing the U.S. Drought Monitor while working with other agencies to improve the tools used to monitor drought. In addition, the NWS’ Advanced Hydrologic Prediction Services (ADPS) program leverages climate outlooks to provide improved water supply forecasts, and NOAA’s Climate Diagnostics Center collaborates with the NWS to incorporate the latest research results into drought forecasting.
Current Drought Status
The current status of the western drought is shown in Figure 1. Severe to extreme drought covers most of the interior sections of the Western United States, (herein referred to as the West) as well as parts of the High Plains. The current situation involves a multi-year drought which began in 1999 across much of the West, worsened in 2000, and continued, with some interruptions, into 2004. However, this winter season has seen improvement in many locations. Snowpack and snow water content have been running close to normal during this winter snow season in many places, especially in the Great Basin and Northwest, and are much improved since last year. Numerous winter storms have been dropping heavy snow over central and northern areas since December and over the Southwest since late February. The Southwest is still lagging, but the drought condition is improving. Continued improvement in water supplies depends largely on snowfall continuing into spring. Furthermore, the pace of spring snow melt is important in relieving drought conditions with a gradual snowmelt preferred over sudden melting.
Mountain snowpack is like money in the bank for western water supplies, as the snowpack contributes anywhere from 50 to 80% of the water supply in this region. Despite recent improvement in the snow conditions, reservoirs remain disturbingly low across most of the region. This is due to the long-term nature of the drought. Impressive deficits in precipitation have built up over the past four to five years. Deficits of 10 to 15 inches of liquid precipitation have occurred over a large area, and in some cases have exceeded over 20 inches, which is more than a year's worth of precipitation. As a result, soils have become exceedingly dry. Reservoir replenishment will be limited as snow melt runoff is absorbed by parched soils.
Reservoirs remain significantly below normal in every western state except California. As of February 1, 2004, four states -- Nevada, New Mexico, Utah, and Oregon – report storage at or below 50% of normal. As a consequence, water restrictions are in place in a number of locations. Water managers expect farmers in the hardest hit areas of the drought region to have reduced access to water for agriculture this spring and summer, as difficult decisions are made to balance the needs of water users -- consumers, the environment, farmers, ranchers, and recreational users. Illustrating the difficult decisions these water managers face, as of January 31, Colorado River Basin water storage stood at 68% of normal, with Lake Powell in Utah at just 57% of normal storage, which is near the 5-year low for water storage.
Historical Perspective
From an historical perspective of droughts in the interior West, some indicators of drought depict the current multi-year drought as one of the most severe in the past 40 to 100 years, comparable to the severe droughts in the 1950s and 1930s in some areas, while not quite as severe in others. For California’s water supply/reservoir storage, this drought is not as bad as the 1988-93 drought.
Colorado River Basin storage this winter has been the lowest in more than 30 years, with Lake Powell at its lowest since 1970, and Lake Mead its lowest since 1968. Since Lake Mead began declining in late 1999, water storage has dropped nearly 40%. Water supply experts in New Mexico are telling us that serious shortages will persist in the state even with above-normal rain and snow this season, and some reservoirs may not even be restored by normal precipitation during the next winter season.
The West is largely a semi-arid region, and water supplies there are especially vulnerable to long-term shortages of precipitation. Historically, there have been long periods with enhanced precipitation as well as long periods with reduced precipitation, often lasting 20 or 30 or more years. Given the recent period from the 1980s into the 1990s had precipitation amounts above historical averages in the Colorado River Basin and the Southwest, it is only natural to expect there will be periods with lesser amounts of precipitation. In addition, population growth has placed increased demands on water supplies, so drought vulnerability has increased because of greater numbers of water users.
The Outlook
In order to fully appreciate the long-term outlook for the drought, it is helpful to understand the meteorological causes and ongoing research issues. Recent research, much of it coming from NOAA laboratories or from NOAA funded projects in universities, gives us some insight into the factors that we believe contributed to the multi-year drought. Studies based on collections of statistical and physical models show the important role that existing ocean and ground conditions play in establishing wind patterns leading to “blocking” in the atmosphere, an important factor in setting up the weather conditions which cause prolonged warm and dry conditions and cause reduced rainfall and above-normal warmth. Climate trends should also be considered when forecasting the future evolution of a drought. The West's climate has been getting warmer for about 20-25 years, especially in the winter and spring. These conditions contribute to the drought by increasing the rate of snow melt in the spring and early summer, and also increase water evaporation.
For the shorter-term drought outlook, trends in mountain snowpack and winter storms, as well as the medium and long-range forecasts of precipitation from CPC are emphasized. The spring-summer streamflow forecasts from USDA/NRCS and NWS hydrologists are an important consideration for the water supply outlook in the West. Precipitation from recent storms has been encouraging, boosting valuable snow packs in the Southwest, an area which missed most of the storms before late February. The recent improvement in the Southwest follows the improvement in moisture conditions farther north earlier this winter, which resulted in some drought relief across much of the Northwest. The official monthly CPC outlook for March suggests at least parts of the Southwest may experience above-normal precipitation. The latest streamflow forecasts for this spring and summer produced by USDA’s NRCS show an improvement to near normal for many central and northern areas of the West, but below normal for the Southwest. However, we expect the March Outlook will reflect the enhanced snowpack and show some improvement in the drought conditions for the Southwest.
Over the medium-term, seasonal forecasts through the next 12 months show no strong signals for above or below normal precipitation. The lack of El Niño or La Niña development creates much uncertainty in the seasonal outlooks, but the fact that the current Pacific Sea Surface Temperature (SST) pattern does not greatly resemble patterns associated with historical western droughts (e.g., cold water in the eastern Pacific) makes us somewhat more optimistic. The latest seasonal drought outlook (Figure 2), which combines forecasts for all time periods out to the end of May and considers recent trends in snowpack, presents a fairly optimistic picture, with likely drought improvement over the Great Basin and in the Great Plains. Limited improvement is possible in central and southern New Mexico and from western Colorado and eastern Utah northward through Wyoming into Montana. Of course, we always emphasize that improvement does not mean total relief. As summer approaches, reservoir levels are expected to remain below normal in many parts of the West.
Research Activities
As our understanding of, and skill in forecasting, the seasonal to interannual climate range improves, the ability to fine tune long term climate models increases as well. However, predictions for long-term climate (herein defined as more than 1 year) at the regional level carry an increased level of uncertainty. In order to reduce that uncertainty, NOAA continues to invest in research to better understand the interdependencies of the ocean and land and the combined influence on climate. Recent data shows a warming trend for the past several decades over much of the West, especially during the winter season. Climate models, using historical data, accurately predict temperature increases consistent with this observed long term warming trend. These models project the general warming trend will continue for the remainder of this century. However, neither climate model predictions nor observations show any identifiable trend in precipitation.
Research at NOAA’s Climate Diagnostics Center indicates recent decadal swings in precipitation in the West may be largely attributable to decadal variations in ocean temperatures, especially in the tropical Pacific and Indian Oceans. The causes of these ocean temperature variations are themselves not fully understood, but undoubtedly due in part to strong natural variability in the coupled atmosphere-ocean system, such as occurs with El Niño-Southern Oscillation. Even with unchanging total precipitation in this region, changes in temperatures may significantly influence the annual water cycle as well as water demand, with subsequent implications for water management.
NOAA continues to invest in research on the causes of decadal oscillations in the Pacific and Atlantic oceans and the role they play behind long-term drought. In addition, NOAA and sister science agencies in Mexico are co-leading the North American Monsoon Experiment (NAME), an international effort to enhance understanding of the sources and limits of predictability of warm season precipitations over North America, with emphasis on time scales from seasonal to interannual. Improved understanding and prediction of monsoon rainfall in the southwestern U.S. and Mexico is critical for water resource management in the region.
NOAA also supports four university-based Regional Integrated Sciences and Assessments (RISAs) programs in the Western U.S. that develop and provide improved drought information for decision-makers. Each of the four RISAs (located in Washington, California, Arizona and Colorado) focuses on regional issues related to assessing drought impacts, and improving the use and usefulness of forecasts and monitoring products for impact mitigation and cost reduction.
The Role of the President’s Climate Change Research Initiative
Mr. Chairman, I would also like to bring your attention to the important work begun under the President’s Climate Change Research Initiative (CCRI) and the U.S. Climate Change Science Program (CCSP). Our ability to understand the large and complex forces at work on the planet will enable us to help develop high quality information for operational use by public works officials, city and county planners, forestry experts, and others charged with the responsibility of managing natural resources in communities across the nation. Furthering the science of climate change also helps policymakers on the local, state, and national levels make informed decisions.
The President’s call to advance climate change science and focus on the key uncertainties came to fruition in July 2003 when Secretary of Commerce Donald Evans and Secretary of Energy Spencer Abraham unveiled the Strategic Plan of the U.S. Climate Change Science Program, a ten year management plan for climate research in the federal government that, for the first time, introduces goals, deadlines, and deliverables.
The Strategic Plan is also a milestone for drought and water research. Contained within it are research goals for the following areas:
· Global water cycle, including measurably improved forecasts of precipitation and other water cycle variables for water managers, and increases in the efficiency of water use through better water models for policy and planning;
· Land use and land cover change: identifying past and projected trends in land cover or land use that are attributable to changes in climate, and identifying U.S. regions where climate change may have the greatest implications for land management;
· Ecosystems: developing information to support management decisions for agricultural lands, forests, fisheries, and other ecosystems under conditions of environmental change.
When one takes into consideration the increase in population in the western United States and the challenges this expansion poses for resource management, the Administration’s Strategic Plan comes at a critical juncture – and will hopefully advance the state of knowledge for drought and water research in a way that assists resource managers and policymakers in their planning and policymaking.
Collaboration with Other Agencies
NOAA collaborates with many state and Federal agencies (e.g., NASA, EPA, USGS, and others) and universities to monitor, understand and predict drought. For example, NOAA works with USDA and the National Drought Mitigation Center in Lincoln, Nebraska to produce the weekly U.S. Drought Monitor, which also uses input from many other Federal and state agencies as well as feedback from a network of over 100 experts around the nation. NOAA works closely with USDA/NRCS on water supply forecasting in the western U.S., and relies on the USGS for streamflow data critical to both water supply and flood forecasting. NOAA also recently began collaborating with Canadian and Mexican meteorologists to produce an experimental North American Drought Monitor.
NOAA's National Weather Service is modernizing its network of cooperative observation sites to provide better coverage and more accurate measurements to aid in measuring drought. We are working with the Western Governors’ Association to plan an ambitious program -- the National Integrated Drought Information System (NIDIS) -- to significantly enhance our ability to monitor drought across the country. Although the biggest challenge for NIDIS is to establish a modern, dense network of observing locations to observe and monitor all aspects of drought (a national integrated mesonet), the plan envisions greatly enhanced access to an entire range of data and information on drought conditions, impacts, and forecasts, and supported by a focused drought research program. NIDIS involves collaborating with many agencies to accomplish its goal, but NOAA will provide key leadership to establish NIDIS. We expect that this plan will be presented to the western governors at the annual WGA meeting in June 2004.
For drought forecasting, NOAA’s Climate Prediction Center is developing techniques to forecast drought over seasonal periods. It issues outlooks at least once each month covering the next three and one-half months. CPC drought forecasters have been meeting with forecasters and researchers both inside and outside the U.S. to explore methods to improve the drought outlooks. Advanced forecast methods based on statistical and global numerical models will continue to be incorporated into drought outlooks, using the best forecasting tools and research available.
As part of NOAA’s Advanced Hydrologic Prediction Service, the NWS will leverage increasing skill in climate forecasts to provide state of the art water supply forecasts for water management and other state and regional agencies.
Outside the West, where many areas depend on water stored in large reservoirs, summertime drought forecasts rely on long-term precipitation forecasts, and the usefulness of these forecasts will always be greatly limited by the arbitrary nature (“hit and miss”) of summertime showers and thunderstorms over the U.S. Much work is needed to upgrade seasonal and longer-term outlooks. NOAA’s research community will continue to interact with researchers throughout the country and the world in programs, such as this year’s North American Monsoon Experiment (NAME) activity, to improve climate and statistical models, enabling a steady increase in our understanding of the causes of drought. Learning the mechanisms triggering drought will enable us to better forecast the likelihood of drought development months and years ahead of time.
We are encouraged by recent research that helps to explain the reasons behind drought development. It is a continuing challenge to produce seasonal forecasts that are consistently accurate. However, as with our weather forecasts, we believe we can keep improving.
Mr. Chairman, this concludes my testimony. I thank you for the opportunity to discuss drought and water supply in the West and the role NOAA plays in drought monitoring, forecasting and research. This topic is critical given the increasing population in the West and the increasing demand for drought information to help manage the demand for water. I would be happy to answer any questions you or other Members of the Committee may have.
Figure 1
