Gregory B. Goodrich

Influence of the Pacific Decadal Oscillation on Winter Precipitation and Drought during Years of Neutral ENSO in the Western United States

Abstract The influence of the Pacific decadal oscillation (PDO) on important hydroclimatic variables during years of neutral ENSO for 84 climate divisions in the western United States is analyzed from 1925 to 1998. When the 34 neutral ENSO years are split by cold (12 yr) and warm (22 yr) PDOs, the resulting winter precipitation patterns are spatially similar to those that occur during years of La Nina–cold PDO and, to a lesser extent, years of El Nino–warm PDO, respectively, although the characteristic ENSO dipole is not evident. The PDO influence is similar when the winter Palmer drought severity index is analyzed, although the core area of influence moves from the Southwest to the northern Rockies. Correlations between Nino-3.4 SSTs and the hydroclimatic variables reverse sign when the neutral ENSO years are split by PDO phase. The greatest difference between correlations occurs in the characteristic dipole between the Pacific Northwest and the desert Southwest. Since seasonal forecast guidance based on...

HEAT MORTALITY VERSUS COLD MORTALITY A Study of Conflicting Databases in the United States

Abstract Studies, public reports, news reports, and Web sites cite a wide range of values associated with deaths resulting from excessive heat and excessive cold. For example, in the United States, the National Climatic Data Centers Storm Data statistics of temperature- related deaths are skewed heavily toward heat-related deaths, while the National Center for Health Statistics Compressed Mortality Database indicates the reverse—4 times more people die of “excessive cold” conditions in a given year than of “excessive heat.” In this study, we address the fundamental differences in the various temperature-related mortality databases, assess their benefits and limitations, and offer suggestions as to their use. These datasets suffer from potential incompleteness of source information, long compilation times, limited quality control, and the subjective determination of a direct versus indirect cause of death. In general, these separate mortality datasets should not be combined or compared, particularly with ...

Climatological Drought in Arizona: An Analysis of Indicators for Guiding the Governor's Drought Task Force

Abstract Lacking a federal policy to address local water deficiencies within the United States, many states have developed their own methods for monitoring drought in an effort to mitigate its effects. This article provides an overview of efforts to standardize the use of drought indices in order to compare recent and historical drought both spatially and temporally for Arizona. Yearly averages of the Palmer Drought Severity Index and the Standardized Precipitation Index are placed into a frequency distribution to create standardization among the indices. The 1896–1904 drought ranked as the most severe, although the 1996–2004 drought was a close second.

Influence of the Pacific Decadal Oscillation on Arizona Winter Precipitation during Years of Neutral ENSO

Abstract Recent studies indicate that correlations between ENSO and winter precipitation in the southwestern United States may vary with the phase of the Pacific decadal oscillation (PDO). In-phase relationships between ENSO and the PDO strengthen the impact of ENSO on winter precipitation, while out-of-phase relationships weaken this impact. It has been suggested that this knowledge of PDO phase can improve long lead winter forecasts. However, all of these studies have focused on the impact of the PDO on both El Nino and La Nina only. Years of neutral ENSO have been neglected even though neutral years occur roughly half the time and coincide with highly variable winter precipitation. It is expected that some of this variability may be caused by the phase of the PDO, although the extent of its relationship with ENSO is not well understood. When years of neutral ENSO from 1925 to 1998 are split by PDO phase, it is found that Arizona winter precipitation and its predictability are strongly influenced. Years...

Using Teleconnections to Predict Wildfires in Mississippi

Abstract Previous wildfire research in the United States has been focused primarily on the western states. Much of this research has discovered relationships between wildfire variability and atmospheric teleconnections. Thus far, few published projects have addressed the effects of various teleconnections on wildfire in the southeastern United States. Index values for the El Nino–Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Pacific decadal oscillation (PDO), and Pacific–North American (PNA) pattern are all tested for relationships with fire variables in the state of Mississippi. Each of the indices displays significant correlations with wildfire occurrence and/or size in Mississippi. The findings of this research suggest that it might be feasible to create predictive fire-risk models for the southeastern United States based on the combination of these teleconnection indices.

Climatic Controls and Hydrologic Impacts of a Recent Extreme Seasonal Precipitation Reversal in Arizona

Abstract The winter (December–February) of 2005/06 ranked as the driest in the instrumental record (since 1895) for nearly all regions of Arizona. The city of Phoenix, Arizona, recorded no precipitation during this time period, which was part of a record dry streak of 143 days without measurable precipitation. More important, the Salt and Verde watersheds, which supply the greater Phoenix area with approximately 50% of its water supply, received less than 3% of normal precipitation. Remarkably, this historically dry winter was preceded by the second wettest winter on record in 2004/05, a winter that filled reservoirs statewide and ameliorated a drought that has persisted since 1996 in some parts of the state. This study begins with a brief overview of the historical context of such reversals of extreme seasonal precipitation in Arizona followed by an analysis of the teleconnective impacts. The authors find that while an extreme reversal such as this has only happened once before in Arizona (1904/05 and 19...

The Influence of the PDO on Winter Precipitation During High- and Low-Index ENSO Conditions in the Eastern United States

It is well established that, when high-index ENSO (El Nińo and La Nińa) and the PDO (Pacific Decadal Oscillation) are in the same (different) phase, the impact of the ENSO phase on winter precipitation is enhanced (weakened) in the western United States. During years of low-index (neutral) ENSO conditions, spatial patterns of winter precipitation are similar to those of La Nińa during cold PDO and El Nińo during warm PDO, particularly in the southwestern U.S. Unknown, however, is whether the PDO influence during years of neutral ENSO exists east of the Rocky Mountains. We analyzed the influence of the PDO on winter precipitation during years of high- and low-index ENSO conditions for 260 climate divisions in the eastern U.S. from 1925 to 1998. When the 33 neutral ENSO years are split by cold (12 years) and warm (21 years) PDO, the resulting winter precipitation patterns show wetter (drier) than average conditions in nearly all (80%) of the 260 climate divisions during the warm (cold) phase of the PDO. The two ENSO/PDO combinations with the driest signals for the eastern U.S. are La Nińa/warm PDO and neutral ENSO/cold PDO. The modulation effect of the PDO is significant during La Nińa in northern Texas and parts of New England and during neutral ENSO in southern Texas and the northern Plains. We suggest that seasonal forecasters in these regions may use this knowledge to improve long-lead winter forecasts during those ENSO phases, assuming the current PDO phase is well established.

Droughts of the twentieth and early twenty-first centuries: Influences on the production of beef and forage in Kentucky, USA

Drought affects societies world-wide in many different ways. It is a natural hazard that is complex and not well understood and as a result, its impacts are often poorly documented. The purpose of this research is to quantify (in dollars) the impacts of drought on Kentuckys beef and forage (hay) production. Observations suggest that the most important droughts in Kentucky occurred in 1930-31, 1940-42, 1952-55, 1987-88, 1999-2000 and 2007. The total state revenue for these commodities were analyzed during these severe drought years and non-drought years. The research estimated revenue deficit from these severe droughts in Kentucky for these (beef and hay) agricultural commodities. This study is important to the general public as well as planners and policy makers. Proper documentation of drought impacts should help identify drought vulnerabilities and result in better risk management and mitigation.

The 2007 Mid-South Summer Drought and Heat Wave in Historical Perspective

The 2007 summer drought and heat wave that scorched Kentucky and Tennessee affected stakeholders in the agriculture, tourism, and water supply industries, among others. The drought and heat wave also generated large amounts of media coverage and was touted as being among the worst in history. But how does the 2007 summer drought and heat wave that affected the Mid-South rank compared to the notable droughts in the 1930s, 1940s, and 1950s? Using climate division data and state composite data for Kentucky and Tennessee we performed a statistical analysis that allowed us to place the 2007 summer drought and heat wave into proper historical perspective. While the 2007 drought was among the all-time worst in Tennessee history, there have been many more notable drought periods in Kentucky.

How Well Does Sky Harbor International Airport Characterize Winter Precipitation in the Phoenix Area

Abstract Sky Harbor International Airport (SKA) is the first-order weather station in the Phoenix metropolitan area. Meteorological variables from the weather station, including precipitation, are reported by the media to the general public as the official weather results for the Phoenix metropolitan area, which measures more than 15,000 square miles. While temperature is a continuous meteorological parameter that does not vary much spatially across Phoenix, precipitation is a discrete and more variable weather phenomenon, even during winter, when mid-latitude storms bring wide swaths of precipitation to Arizona. Does the precipitation measured at Sky Harbor International Airport spatially characterize precipitation in the rest of the Phoenix area during winter? Have correlations between Sky Harbor winter precipitation and the rest of the Phoenix area changed over time? Precipitation data for the months of December to March were compiled for 28 Phoenix area weather stations for the time period 1990–2004 and for 8 stations from 1954–2004. Five definitions of precipitation, including total, frequency, intensity, duration, and true intensity were developed to define precipitation. Regression equations using Sky Harbor precipitation as the independent variable were run to determine correlations and variance explained with surrounding stations. Additional regressions were run on subsets of the 1954–2004 data to determine if correlations have changed over time. Overall, Sky Harbor explains between 71 to 99% of total seasonal precipitation and between 85 to 98% of the seasonal frequency, although these numbers are significantly reduced for daily data. Locations closer to Sky Harbor are more highly correlated for all variables than those farther away. Correlation coefficients show significant changes due to the urban heat island as well from climate teleconnections.