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Abstract
Long-term precipitation records indicated that, on the average, 15% more warm season precipitation falls on the forested western Shawnee Hills of southern Illinois than falls on the rural farm flatlands at 120 m lower elevations both north and south of the hills. This precipitation difference with relatively little elevation change offered an interesting opportunity to study the effect of orographic and land-use differences upon convective precipitation. Initially, two methods differing in scale and time were used to delineate the bill anomaly and to investigate its causes. Extensive climatic studies of all available precipitation data revealed that the effect of the hills was most pronounced during the warm season when showers and thunderstorms are the major source of precipitation. A subsequent 5-yr study involving a dense recording raingage and wind recording network showed that the hill-related increases apparently came through enhancement of heavy showers, particularly those associated with squall-line and cold-frontal conditions. This led to an intensive field study in July 1970 described in the companion paper (Part 2).
Abstract
Long-term precipitation records indicated that, on the average, 15% more warm season precipitation falls on the forested western Shawnee Hills of southern Illinois than falls on the rural farm flatlands at 120 m lower elevations both north and south of the hills. This precipitation difference with relatively little elevation change offered an interesting opportunity to study the effect of orographic and land-use differences upon convective precipitation. Initially, two methods differing in scale and time were used to delineate the bill anomaly and to investigate its causes. Extensive climatic studies of all available precipitation data revealed that the effect of the hills was most pronounced during the warm season when showers and thunderstorms are the major source of precipitation. A subsequent 5-yr study involving a dense recording raingage and wind recording network showed that the hill-related increases apparently came through enhancement of heavy showers, particularly those associated with squall-line and cold-frontal conditions. This led to an intensive field study in July 1970 described in the companion paper (Part 2).
Abstract
The studies described in the companion paper (Part 1) led to an intensive field study in July 1970. The field study employed networks of recording raingages, wind recorders, and hygrothermographs, along with a meteorological radar, cloud cameras, and a meteorologically-instrumented aircraft. The study occurred in an abnormally dry period with mostly air mass showers (non-frontal storm). These air mass showers were found to be enhanced partially by the moisture derived from the forested hills under low wind speed conditions. In addition, the low speed winds from the south were found to be directed by the valleys within the hills, so as to develop a convergent pattern above the hills where the atmosphere was convectively unstable.
Abstract
The studies described in the companion paper (Part 1) led to an intensive field study in July 1970. The field study employed networks of recording raingages, wind recorders, and hygrothermographs, along with a meteorological radar, cloud cameras, and a meteorologically-instrumented aircraft. The study occurred in an abnormally dry period with mostly air mass showers (non-frontal storm). These air mass showers were found to be enhanced partially by the moisture derived from the forested hills under low wind speed conditions. In addition, the low speed winds from the south were found to be directed by the valleys within the hills, so as to develop a convergent pattern above the hills where the atmosphere was convectively unstable.
This paper reviews recent work on trends during this century in societal impacts (direct economic losses and fatalities) in the United States from extreme weather conditions and compares those with trends of associated atmospheric phenomena. Most measures of the economic impacts of weather and climate extremes over the past several decades reveal increasing losses. But trends in most related weather and climate extremes do not show comparable increases with time. This suggests that increasing losses are primarily due to increasing vulnerability arising from a variety of societal changes, including a growing population in higher risk coastal areas and large cities, more property subject to damage, and lifestyle and demographic changes subjecting lives and property to greater exposure.
Flood damages and fatalities have generally increased in the last 25 years. While some have speculated that this may be due in part to a corresponding increase in the frequency of heavy rain events, the climate contribution to the observed impacts trends remains to be quantified. There has been a steady increase in hurricane losses. However, when changes in population, inflation, and wealth are considered, there is instead a downward trend. This is consistent with observations of trends in hurricane frequency and intensity. Increasing property losses due to thunderstorm-related phenomena (winds, hail, tornadoes) are explained entirely by changes in societal factors, consistent with the observed trends in the thunderstorm phenomena. Winter storm damages have increased in the last 10–15 years and this appears to be partially due to increases in the frequency of intense nor'easters. There is no evidence of changes in drought-related losses (although data are poor) and no apparent trend in climatic drought frequency. There is also no evidence of changes in the frequency of intense heat or cold waves.
This paper reviews recent work on trends during this century in societal impacts (direct economic losses and fatalities) in the United States from extreme weather conditions and compares those with trends of associated atmospheric phenomena. Most measures of the economic impacts of weather and climate extremes over the past several decades reveal increasing losses. But trends in most related weather and climate extremes do not show comparable increases with time. This suggests that increasing losses are primarily due to increasing vulnerability arising from a variety of societal changes, including a growing population in higher risk coastal areas and large cities, more property subject to damage, and lifestyle and demographic changes subjecting lives and property to greater exposure.
Flood damages and fatalities have generally increased in the last 25 years. While some have speculated that this may be due in part to a corresponding increase in the frequency of heavy rain events, the climate contribution to the observed impacts trends remains to be quantified. There has been a steady increase in hurricane losses. However, when changes in population, inflation, and wealth are considered, there is instead a downward trend. This is consistent with observations of trends in hurricane frequency and intensity. Increasing property losses due to thunderstorm-related phenomena (winds, hail, tornadoes) are explained entirely by changes in societal factors, consistent with the observed trends in the thunderstorm phenomena. Winter storm damages have increased in the last 10–15 years and this appears to be partially due to increases in the frequency of intense nor'easters. There is no evidence of changes in drought-related losses (although data are poor) and no apparent trend in climatic drought frequency. There is also no evidence of changes in the frequency of intense heat or cold waves.
Societal impacts from weather and climate extremes, and trends in those impacts, are a function of both climate and society. United States losses resulting from weather extremes have grown steadily with time. Insured property losses have trebled since 1960, but deaths from extremes have not grown except for those due to floods and heat waves. Data on losses are difficult to find and must be carefully adjusted before meaningful assessments can be made. Adjustments to historical loss data assembled since the late 1940s shows that most of the upward trends found in financial losses are due to societal shifts leading to ever-growing vulnerability to weather and climate extremes. Geographical locations of the large loss trends establish that population growth and demographic shifts are the major factors behind the increasing losses from weather–climate extremes. Most weather and climate extremes in the United States do not exhibit steady, multidecadal increases found in their loss values. Without major changes in societal responses to weather and climate extremes, it is reasonable to predict ever-increasing losses even without any detrimental climate changes. Recognition of these trends in societal vulnerability to weather-climate extremes suggests that the present focus on mitigating the greenhouse effect should be complemented by a greater emphasis on adaptation. Identifying and understanding this societal vulnerability has great importance for understanding the nation's economy, in guiding governmental policies, and for planning for future mitigative activities including ways for society to adapt to possible effects of a changing climate.
Societal impacts from weather and climate extremes, and trends in those impacts, are a function of both climate and society. United States losses resulting from weather extremes have grown steadily with time. Insured property losses have trebled since 1960, but deaths from extremes have not grown except for those due to floods and heat waves. Data on losses are difficult to find and must be carefully adjusted before meaningful assessments can be made. Adjustments to historical loss data assembled since the late 1940s shows that most of the upward trends found in financial losses are due to societal shifts leading to ever-growing vulnerability to weather and climate extremes. Geographical locations of the large loss trends establish that population growth and demographic shifts are the major factors behind the increasing losses from weather–climate extremes. Most weather and climate extremes in the United States do not exhibit steady, multidecadal increases found in their loss values. Without major changes in societal responses to weather and climate extremes, it is reasonable to predict ever-increasing losses even without any detrimental climate changes. Recognition of these trends in societal vulnerability to weather-climate extremes suggests that the present focus on mitigating the greenhouse effect should be complemented by a greater emphasis on adaptation. Identifying and understanding this societal vulnerability has great importance for understanding the nation's economy, in guiding governmental policies, and for planning for future mitigative activities including ways for society to adapt to possible effects of a changing climate.
Abstract
Through a computer-based system, weather data from Illinois are collected daily, checked, and summarized into various climatic products within hours after collection. This system was controlled for two years to demonstrate system feasibility, determine user interest and product desires, and plan for statewide urge. This study focuses on usage of system products. The private sector (agribusiness news media, and private industry) was the most frequent and persistent user group, suggesting user-pay as a possible approach for funding such a system. State and federal agencies, farmers, and extension agents also use the system but primarily during weather stress periods. The characteristics of usage should help in the design and selection of products in other emerging state and regional systems for dissemination of climate data and information. The usage patterns also indicate how climate conditions impact various private and public sectors in a humid continental climate.
Abstract
Through a computer-based system, weather data from Illinois are collected daily, checked, and summarized into various climatic products within hours after collection. This system was controlled for two years to demonstrate system feasibility, determine user interest and product desires, and plan for statewide urge. This study focuses on usage of system products. The private sector (agribusiness news media, and private industry) was the most frequent and persistent user group, suggesting user-pay as a possible approach for funding such a system. State and federal agencies, farmers, and extension agents also use the system but primarily during weather stress periods. The characteristics of usage should help in the design and selection of products in other emerging state and regional systems for dissemination of climate data and information. The usage patterns also indicate how climate conditions impact various private and public sectors in a humid continental climate.
Abstract
As part of research concerned with operational seeding and evaluation techniques, analyses were made of two warm-season seeding projects involving rainfall enhancement: a 5-year (1975–79) aircraft seeding program conducted in 15 southwestern Kansas counties, and a ground generator seeding project conducted in 3 counties of northwestern Oklahoma in 1972–76. Data for 153 and 111 seeding days in Kansas and Oklahoma, respectively, were used. Rainfall data were obtained from the climatic raingage network of the National Weather Service. Seeding-day data were gratified according to meteorological parameters, including synoptic storm type, storm motion, and plume movement derived from the low-level wind field. Comparisons of 24-hour rainfall amounts in target and control areas were made. Movable controls determined from storm motions obtained from hourly radar data and upper-level winds were used to minimize control contamination by the seeding agent. In the southwestern Kansas operation, results indicated a target increase of 9% in the warm season rainfall, but this modest increase does not provide firm support for seeding enhancement considering rainfall natural variability, rainfall sampling deficiences, and other sources of sampling error. In the Oklahoma project, no substantial support was established for seeding-induced rainfall from the ground generator operations.
Abstract
As part of research concerned with operational seeding and evaluation techniques, analyses were made of two warm-season seeding projects involving rainfall enhancement: a 5-year (1975–79) aircraft seeding program conducted in 15 southwestern Kansas counties, and a ground generator seeding project conducted in 3 counties of northwestern Oklahoma in 1972–76. Data for 153 and 111 seeding days in Kansas and Oklahoma, respectively, were used. Rainfall data were obtained from the climatic raingage network of the National Weather Service. Seeding-day data were gratified according to meteorological parameters, including synoptic storm type, storm motion, and plume movement derived from the low-level wind field. Comparisons of 24-hour rainfall amounts in target and control areas were made. Movable controls determined from storm motions obtained from hourly radar data and upper-level winds were used to minimize control contamination by the seeding agent. In the southwestern Kansas operation, results indicated a target increase of 9% in the warm season rainfall, but this modest increase does not provide firm support for seeding enhancement considering rainfall natural variability, rainfall sampling deficiences, and other sources of sampling error. In the Oklahoma project, no substantial support was established for seeding-induced rainfall from the ground generator operations.
Abstract
A three-step process is proposed to be most efficient for generating skillful climate forecasts which could reduce the adverse socioeconomic effects of climatic variability. These steps involve identifying weather-sensitive economic sectors, documenting the flexibility of these sectors with respect to likely forecast information, and the development of accordingly focused forecast capabilities. An illustration of the types of information needed to identify sector flexibility is provided for Midwest crop production. Finally, a pilot study using actual farmer data for east central Illinois suggests that increased corn yields could have resulted if producers had been forewarned of the benign weather conditions experienced during the 1979 growing season. This implies that skillful, properly structured climate forecasts may be useful to Midwest crop producers.
Abstract
A three-step process is proposed to be most efficient for generating skillful climate forecasts which could reduce the adverse socioeconomic effects of climatic variability. These steps involve identifying weather-sensitive economic sectors, documenting the flexibility of these sectors with respect to likely forecast information, and the development of accordingly focused forecast capabilities. An illustration of the types of information needed to identify sector flexibility is provided for Midwest crop production. Finally, a pilot study using actual farmer data for east central Illinois suggests that increased corn yields could have resulted if producers had been forewarned of the benign weather conditions experienced during the 1979 growing season. This implies that skillful, properly structured climate forecasts may be useful to Midwest crop producers.
Abstract
A description is given of a broad program to Design and Experiment to Suppress Hail (DESH) in Illinois. This program draws on results acquired during 17 years of extensive hail research in Illinois. There are two principal tasks to DESH: the determination of the desirability and the feasibility of hail suppression experimentation in Illinois and the Midwest. Socio-economic studies have led to an affirmative conclusion on the desirability issues. The feasibility decision appears affirmative and rests on certain key results. Airborne cloud base seeding in the humid midwestern environment is possible but will be more difficult and expensive than in less humid areas. Radar will be needed for short-term forecasting, aircraft operations, identification of potential hailstorms, and in the evaluation of seeding effectiveness. Weather forecasting by objective techniques will be valuable in both operations and evaluation, and adequate objective techniques have been largely developed. The overall shape of the proposed experiment is now clear. It will consist of an impact monitoring effort, which will make assessments of societal, environmental and economic impacts and communicate with the public; an operational effort to execute the experiment according to the final detailed design; and an evaluation effort combining a variety of surface, synoptic and radar data to assess the efficacy of the chosen seeding technique.
Abstract
A description is given of a broad program to Design and Experiment to Suppress Hail (DESH) in Illinois. This program draws on results acquired during 17 years of extensive hail research in Illinois. There are two principal tasks to DESH: the determination of the desirability and the feasibility of hail suppression experimentation in Illinois and the Midwest. Socio-economic studies have led to an affirmative conclusion on the desirability issues. The feasibility decision appears affirmative and rests on certain key results. Airborne cloud base seeding in the humid midwestern environment is possible but will be more difficult and expensive than in less humid areas. Radar will be needed for short-term forecasting, aircraft operations, identification of potential hailstorms, and in the evaluation of seeding effectiveness. Weather forecasting by objective techniques will be valuable in both operations and evaluation, and adequate objective techniques have been largely developed. The overall shape of the proposed experiment is now clear. It will consist of an impact monitoring effort, which will make assessments of societal, environmental and economic impacts and communicate with the public; an operational effort to execute the experiment according to the final detailed design; and an evaluation effort combining a variety of surface, synoptic and radar data to assess the efficacy of the chosen seeding technique.
Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.
Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.
