The study had three main goals: (1) to assess the vulnerability of groundwater-dependent agriculture to climate variability, (2) to identify historical and current processes of adaptation to the vagaries of climate in the region— these refer to both system wide adaptations and individual farmer’s adaptations, and, (3) to assess the use of and needs for seasonal climate forecast information in agricultural decision making. The report is targeted at institutional stakeholders (i.e., agricultural extension personnel), physical scientists (particularly climatologists), and policymakers (at the level of NOAA and other federal agencies). Specific recommendations are made to these groups in order to improve the delivery of seasonal forecasts, set research priorities, and inform public policy.

The information presented here highlights the findings of a drought history study in support of the Governor's Drought Task Force activities, such as determining triggers for drought mitigation and response actions, based on observed hydroclimatic and other information. The material is intended to provide the relevant climatology background for non-specialists, and it is presented in a top ten or frequently asked question format. The questions and answers cover the major climate-related aspects of drought including long-term averages, seasonality, interannual and long-term spatial and temporal drought variations, extremes, and causes of climatic variability. The answers to each question include bulleted Quick Answers followed by a concise explanation of more detailed information. Example figures are presented within the text.

This paper summarizes the current state of knowledge concerning the climate of the Southwest. Low annual precipitation, clear skies, and year-round warm weather over much of the Southwest are due in large part to a quasi-permanent subtropical high-pressure ridge over the region. However, the Southwest is located between the mid-latitude and subtropical atmospheric circulation regimes, and this positioning relative to shifts in these regimes is the fundamental reason for the region's climatic variability. El Niño, which is an increase in sea surface temperature of the eastern equatorial Pacific Ocean with an associated shift of the active center of atmospheric convection from the western to the central equatorial Pacific, has a well developed teleconnection with the Southwest, usually resulting in wet winters. La Niña, the opposite oceanic case of El Niño, usually results in dry winters for the Southwest. Another important oceanic influence on winter climate of the Southwest is a feature called the Pacific Decadal Oscillation, which has been defined as temporal variation in sea surface temperatures for most of the Northern Pacific Ocean. The major feature that sets climate of the Southwest apart from the rest of the United States is the North American monsoon, which, in the US, is most noticeable in Arizona and New Mexico. Up to 50% of the annual rainfall of Arizona and New Mexico occurs as monsoonal storms from July through September.

In support of the Climate Assessment Project for the Southwest, a review was conducted of the current state of weather, climate, and hydrologic forecasting for the Southwest. A key element of the review was a workshop that examined the availability, use, accuracy, and value of forecasts, with participants consisting primarily of agency personnel involved in operational forecasting via directly issuing forecasts, providing key data for making forecasts, or serving as a key link for communicating forecasts. The broad range of forecast products encompasses myriad variables, time-scales from minutes to seasons, and lead-times from minutes to over a year. Current forecast products and techniques are reviewed, and implications for use in decision making are discussed. The forecast review identified needs for additional research to be addressed by the CLIMAS Project, including local evaluation of monthly and seasonal climate outlooks, retrospective evaluation of operational water supply outlooks, hindcast reanalysis of probabilistic water supply outlook techniques, and incorporation of climate outlooks into statistical water supply outlook techniques.