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Annual precipitation in California is more variable than in any other state and is highly influenced by precipitation in winter months. A primary question among stakeholders is whether low precipitation in certain months is a harbinger of annual drought in California. Historical precipitation data from 1895 to 2013 are investigated to identify leading monthly indicators of annual drought in each of the seven climate divisions (CDs) as well as statewide. For this study, drought conditions are defined as monthly/annual (October–September) precipitation below the 20th/30th percentile, and a leading indicator is defined as a monthly drought preceding or during an annual drought that has the strongest association (i.e., joint probability of occurrence) with a statewide annual drought. Monthly precipitation variability and contributions to annual precipitation, along with joint probabilities of drought among the winter months, are first analyzed. Then the probabilities of annual drought and the variability in leading indicators are analyzed according to different climate phases and CDs. This study identified December within a water year as being the leading indicator that is most frequently associated with annual drought statewide (56%) and in most of the CDs (the highest was CD2 at 65%). Associated with its leading-indicator status, December drought was most frequently associated with drought in other winter months ( joint probability . 30%). Results from this study can help stakeholders to understand and assess the likelihood of annual drought events given monthly precipitation preceding or early in the water year. [ABSTRACT FROM AUTHOR]

The article discusses the findings of a survey which asked state drought managers in the 19 Western Governors' Association (WGA) states about drought concerns and impacts, the use of value of drought plans and the types of early warning information that could inform decision and reduce drought damages. The common themes of early warning information to help reduce drought impacts are also described.

Drought preparedness programs are considered a primary defense against drought hazards. This article investigates state drought programs in the western United States, including a review of drought plans and interviews with state drought officials. While nearly all states have developed drought plans and larger drought programs, the scope and depth of these programs vary widely. State programs and plans typically address monitoring, declaration and response, and communication and coordination. Yet few states conduct postdrought assessments or impact and risk assessments. Resources tend to be allocated more for drought response than mitigation. Officials emphasized not only the importance of available monitoring data, but also the need for improved information for monitoring and predicting drought. State drought officials recommended the following: (1) clear and relevant drought indicators and triggers; (2) frequent communication and coordination among state agencies, local governments, and stakeholders; (3) regularly updated drought plans; and (4) strong leadership that includes a full-time state drought coordinator. [ABSTRACT FROM AUTHOR]

A drought monitoring system (DMS) can help to detect and characterize drought conditions and reduce adverse drought impacts. The authors evaluate how a DMS for Washington State, based on a land surface model (LSM), would perform. The LSM represents current soil moisture (SM), snow water equivalent (SWE), and runoff over the state. The DMS incorporates the standardized precipitation index (SPI), standardized runoff index (SRI), and soil moisture percentile (SMP) taken from the LSM. Four historical drought events (1976--77, 1987--89, 2000--01, and 2004--05) are constructed using DMS indicators of SPI/SRI-3, SPI/SRI-6, SPI/SRI-12, SPI/SRI-24, SPI/SRI-36, and SMP, with monthly updates, in each of the state''s 62 Water Resource Inventory Areas (WRIAs). The authors also compare drought triggers based on DMS indicators with the evolution of drought conditions and management decisions during the four droughts. The results show that the DMS would have detected the onset and recovery of drought conditions, in many cases, up to four months before state declarations. [ABSTRACT FROM AUTHOR]

This article presents a technique for performing vulnerability assessments, using measures of exposure, sensitivity, and adaptive capacity. Historically, vulnerability assessments have focused on analyzing the hazard itself, absent information on its causes and mitigations. The vulnerability assessment method (VAM), presented herein, acquires data and information from affected stakeholders to assess not only the hazard, but also the causes of vulnerability, potential for adaptation, previous impacts, and ways to mitigate future impacts. We apply the VAM to a case study of Washington State, assessing drought vulnerability across 34 subsectors. Results indicate highest vulnerability for dryland farmers, farmers with junior water rights, fisheries, ski area operators, berry farmers, and the green industry. Through validation exercises, we demonstrate the VAM’s internal consistency and external applicability. Contributions of the VAM include its incorporation of stakeholder data, integrated and quantitative assessments of vulnerability components, and applicability to other regions, scales, and types of hazards. [ABSTRACT FROM AUTHOR]

Drought plans depend on indicators and triggers to characterize drought conditions and guide drought responses. Yet indicators and triggers often suffer from deficiencies, such as temporal and spatial inconsistency, statistical incomparability, and operational indeterminacy. Further, even though indicators and triggers are vital to drought hazard reduction, they are often selected and used arbitrarily, undermining the potential value of drought plans. Addressing these concerns, this paper provides a process and analytic methods for the development, analysis, and evaluation of indicators and triggers. In addition, this paper details their application to Georgia’s first state drought plan. Results are transferable to other drought plans, offering scientific justification, operational relevancy, and guidance for drought mitigation and response. [ABSTRACT FROM AUTHOR]

Drought management depends on indicators to detect drought conditions, and triggers to activate drought responses. But determining those indicators and triggers presents challenges. Indicators often lack spatial and temporal transferability, comparability among scales, and relevance to critical drought impacts. Triggers often lack statistical integrity, consistency among drought categories, and correspondence with desired management goals. This article presents an approach for developing and evaluating drought indicators and triggers, using a probabilistic framework that offers comparability, consistency, and applicability. From that, a multistate Markov model investigates the stochastic behavior of indicators and triggers, including transitioning, duration, and frequency within drought categories. This model is applied to the analysis of drought in the Apalachicola-Chattahoochee-Flint River Basin in the southeastern United States, using indicators of the Standardized Precipitation Index (for 3, 6, 9, and 12 months), the Palmer Drought Severity Index, and the Palmer Hydrologic Drought Index. The analysis revealed differences among the performance of indicators and their trigger thresholds, which can influence drought responses. Results contribute to improved understanding of drought phenomena, statistical methods for indicators and triggers, and insights for drought management. [ABSTRACT FROM AUTHOR]