For three small, mountainous catchments in Germany two medium-range forecast systems are compared that predict precipitation for up to 5 days in advance. One system is composed of the global German weather service (DWD) model, GME, which is dynamically downscaled using the COSMO-EU regional model. The other system is an empirical (expanded) downscaling of the ECMWF model IFS. Forecasts are verified against multi-year daily observations, by applying standard skill scores to events of specified intensity. All event classes are skillfully predicted by the empirical system for up to five days lead time. For the available prediction range of one to two days it is superior to the dynamical system.

The National Weather Service (NWS) is responsible for ensuring that the U.S is a weather ready nation. The mission of the NWS focuses on protecting the lives and property of those in the U.S, while also enhancing the national economy. The number of high-impact weather events have increased over the past decades, suggesting a need for a more effective NWS. This paper focuses on improving the NWS by following the systems engineering approach and using system architecting principles.

This dissertation traces three ethical dimensions, or values, of weather warnings in the National Weather Service (NWS): an ethic of accuracy, and ethic of care, and an ethic of resilience. Each appear in forecaster work but are not equally visible in the identity of a forecaster as scientific expert. Thus, I propose that the NWS should consider rethinking its science through its relationship to multiple publics, creating what Sandra Harding calls "strong objectivity." To this end, I offer the concept of empathic accuracy as an ethic that reflects the interrelatedness of precision and care that already attend to forecasting work. First, I offer a genealogy of the ethic of accuracy as forecasters see it. Beginning in the 1960s, operational meteorologists mounted an ethic of accuracy through the "man-machine mix," a concept that pointed to an identity of the forecasting scientist that required a demarcation between humans and technologies. It is continually troubled by the growing power of computer models to make predictions. Second, I provide an ethnographic account of the concern expressed by forecasters for their publics. I do so to demonstrate how an ethic of care exists alongside accuracy in their forecasting science, especially during times of crisis. I recreate the concern for others that their labor performs. It is an account that values emotion and is sensitive to context, showing what Virginia Held calls "the self-and-other together" that partially constitutes a forecaster identity. Third, I critique the NWS Weather Ready Nation Roadmap and its emphasis on developing in the public an ethic of resilience. I argue that, as currently framed, this ethic and its instantiation in the initiative Impact Based Decision Support Services narrowly defines community to such an extent that it disappears the public. However, it also reveals other valences of resilience that have the potential to open up a space for an empathetic accuracy. Finally, I close with a co-authored article that explores my own commitment to an ethic of relationality in disaster work and the compromises that create tension in me as a scholar and critical participant in the weather community. / Ph. D.

The SAWS is interested in demonstrating the economic and social benefits of the products or services it provides to the public, industries and other organisations. It is also important for the organisation to carry out ongoing performance assessment of public and commercial weather services to ensure that these services are efficient and effectively meeting the public's and customer's needs and contribute to longer term commercial and societal objectives. Some other National Weather Services has developed "Service Charters" which detail their pledge of performance to the user communities, specifically, customers and the general public. These service charters provide a brief overview of the services provided, a commitment of performance against specific targets and a commitments to consult and identify a means by which the customers and the public may register their concern. As a result the service charters has become an important component of the Weather Services branding measurement strategy. The acceptance of the SAWS products or services by the public and other weather users depends on a number of factors. Scientific accuracy is just one of those factors. Also the health of the SAWS depends on the perceptions from full spectrum of weather users ranging from individual citizens, media, aviation, ... Ill marine, industry, government departments, construction companies, and insurance. These perceptions include those about requirements, accessibility, availability, accuracy, timelines, utility, comprehension, sufficient and packaging. The objective is to ultimately measure performance from the user perspective and identify user's needs. It is also to measure the acceptance of the services provided from such dimensions as expectations, understanding, importance, satisfaction, and utility. This study has been framed within the hypothesis that the SAWS brand associations are not strong, not favourable and not unique to create a positive brand. It has come critical to assess the level of customer awareness and familiarity with the SAWS brand so as to improve the dissemination mechanisms of the weather forecast information. Based on a literature review, two types of brand association are identified. One is product association including functional attribute association and non-functional attribute association. The other is organisational association including corporate ability association and corporate social responsibility association. It has been found that, the greater the number of the core brand association, the higher the brand equity. The feedback received on the questionnaire and interviews directed at awareness and familiarity with the SAWS brand indicated that, a need exists to educate the public and potential customers about the products and services of the SAWS. Of paramount important is the improvement of the SAWS dissemination mechanisms and partnerships with other scientific research organisations. This will enable the SAWS to reach a wide range of the public and weather users and to safeguard property and life of all South Africans. / Thesis (MBA)-University of KwaZulu-Natal, Durban, 2005.

In 2006 a Numerical Weather Prediction (NWP) model known as the Unified Model (UM) from the United Kingdom Meteorological Office (UK Met Office) was installed at the South African Weather Service (SAWS). Since then it has been used operationally at SAWS, replacing the Eta model that was previously used. The research documented in this dissertation was inspired by the need to verify the performance of the UM in simulating and predicting weather over South Africa. To achieve this aim, three model configurations of the UM were compared against each other and against observations. Verification of rainfall as well as minimum and maximum temperature for the year 2008 was therefore done to achieve this. 2008 is the first year since installation, where all the configurations of the UM used in the study are present. For rainfall verification the model was subjectively verified using the eyeball verification for the entire domain of South Africa, followed by objective verification of categorical forecasts for rainfall regions grouped according to standardized monthly rainfall totals obtained by cluster analysis and finally objective verification using continuous variables for selected stations over South Africa. Minimum and maximum temperatures were subjectively verified using the eyeball verification for the entire domain of South Africa, followed by objective verification of continuous variables for selected stations over South Africa, grouped according to different heights above mean sea level (AMSL). Both the subjective and objective verification of the three model configurations of the UM (for both rainfall as well as the minimum and maximum temperatures) suggests that 12km UM simulation with DA gives better and reliable results than the 12km and 15km UM simulations without DA. It was further shown that although there was no significant difference between the model outputs from the 12km and the 15km UM without DA, the 15km UM simulation without DA, proved to me more reliable and accurate than the 12km UM simulation without DA in simulating minimum and maximum temperatures over South Africa, on the other hand the 12km UM simulation without DA is more reliable and accurate than the 15km UM simulation without DA in simulating rainfall over South Africa. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Geography, Geoinformatics and Meteorology / unrestricted

Positive lightning flashes are known to be more intense and cause more damage than negative flashes, although positive flashes only occur about 10% of the time. This study expounds on cloud microphysical aspects of thunderstorms and investigates the occurrence, timing and location of ice particles within thunderstorms and correlates this to the occurrence of positive cloud-to-ground lightning events. Satellite data obtained from the Meteosat Second Generation (MSG) satellite, were used to: 1) depict Cloud Top Temperatures (CTT) by considering Infra Red (IR) radiation with a wave length of 10.8μm, 2) compare results from the CTT with the Brightness Temperature Difference (BTD) calculated by subtracting IR10.8μm from IR8.7μm, 3) after the cloud particle phase was determined from the abovementioned comparison, the sum of cloud-to-ground lightning strokes over a 1-hour period around the time of a reported lightning fatality was compared with cloud microphysical properties and then 4) these results were further compared with the lightning polarity obtained from the South African Weather Service (SAWS) Lightning Detection Network (LDN) data set. Four case studies were identified to investigate from the many available case study dates. These four cases occurred on 3 separate days namely: 1)22 November 2007, iii 2) 10 February 2009 and 3) 29 October 2009. There were two fatal events reported on 22 November 2007 and therefore two cases studies were compiled for this one date. On 10 February 2009 over 250 insurance damage claims were honoured but no fatality was reported. The three case studies mentioned above were classified as primary case studies. The 29 October 2009 case was classified as a secondary, more generalized case which was chosen in order to test whether the results gained from the first three cases were indeed noteworthy. Results gathered from two of the three primary case studies showed that the fatalities occurred when the most intense part of the thunderstorm was to the east of the location where the lightning struck the victims, although actual storm properties were not considered as being particularly severe. The lightning data for the primary case studies showed that the percentage of cloud-to-ground lightning was within 10% of the total number of strokes recorded for 22 November 2007, and above 10% for 10 February 2009. In the one secondary case study of 29 October 2009 the percentage of positive lightning was only between 2% and 4% of the total number of strokes recorded, which was significantly lower than in the three primary cases. A significant difference in cloud microphysics between the primary and secondary cases was the possible occurrence of super-cooled liquid water found in Cumulonimbus (CB) clouds in the secondary case. This could have been a determining factor for the difference in percentage of positive lightning between the primary and secondary case studies. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Geography, Geoinformatics and Meteorology / unrestricted

The South African Weather Service rainfall seasonal forecasts are verified for the period of January-February-March to October-November-December 1998-2004. These forecasts are compiled using different models from different institutions. Probability seasonal forecasts can be evaluated using different skill measures, but in this study the Ranked Probability Skill Score (RPSS), Reliability Diagram (RD) and Relative Operating Characteristics (ROC) are used. The RPSS is presented in the form of maps whereas the RD and ROC are analyses are presented in the form of graphs. The aim of the study is to present skill estimates of operational seasonal forecasts issued at South African Weather Service A limited number of forecasts show positive RPSS value throughout the validation period. From RD and ROC analysis, there is no skill in predicting the normal category as compared to below-normal and above-normal categories. Notwithstanding, the frequency diagrams show that the normal category was often given a large weight in the operational forecasts. The value of verifying seasonal forecast accuracy from the user’s perspective is important. The understanding of seasonal forecast performance helps decision makers to determine when and how to respond to expected climate anomalies. Therefore the frequent update of the seasonal forecast verification is important in order to help Users make better decisions. Copyright / Dissertation (MSc)--University of Pretoria, 2008. / Geography, Geoinformatics and Meteorology / Unrestricted

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Alabama, also known as the Dixie state, is no stranger to severe weather. Severe weather can occur during much of the year. Experienced local forecasters have long suspected that North and Central Alabama has its own tornado alley. Many of these forecasters have noticed storm tracks as well as tornado tracks to be similar to past historic events. Many questions have risen about the exact influential factors that cause convective initiation and tornadic development. For example the effects of terrain, water, and population on tornado climatology will be discussed in this study. The sometimes unreliable climatology of tornadoes will be addressed as well as the history of storm reporting. Tornado clusters were found and further explained regarding relationships with terrain, water, and population. Through this research, it is concluded that there are two distinct tornado regions that exist in North and Central Alabama.

Heat stress occurs when the body cannot adequately cool itself due to the combined contributions of metabolic heat, environmental factors and clothing. Heat stress found in the workplace puts employees at risk of developing heat-related illnesses, disorders and could be fatal. The wet bulb globe temperature (WBGT) index is the current method used to assess environmental contributions to heat stress in an occupational setting. The purpose of this thesis was to explore whether the National Weather Service's Heat Index (HI) could substitute for the WBGT Index during occupational heat stress exposure assessment. The possibility of using the HI for heat stress exposure assessments was explored by first developing an occupational exposure limit based on the HI and then by comparing the HI to WBGT Index over a range of environments. Data from 10 selected studies were reviewed and categorized into two groups (Classic Data and Progressive Data) based on the method used to determine the upper limit of the prescriptive zone. WBGT and HI values were estimated from the environmental data provided in the 10 studies and the metabolic demands were also noted. These data were used to illustrate the relationship between environment (WBGT and HI) and metabolic rate. Next the relationship between HI and WBGT was compared over a range of environments consisting of combinations of air temperature and percent relative humidity as defined by the NWS's Heat Index Chart. Finally the effects of adding a high radiant heat load (Tg = Tdb+10 °C) to the relationship between WBGT and HI was explored. The HI occupational exposure limits were protective of the upper limit threshold points in a manner similar to WBGT. A greater spread in the Classic and Progressive upper limit data was observed above the occupational exposure limit when expressed as HI. High correlation was observed (R2 = 0.95) between the WBGT Index and HI over a range of environments, assuming no radiant heat. The incremental increase in HI due to high radiant heat indicated a strong dependency on the absolute value of HI, which makes using HI to predict WBGT in radiant heat environments problematic. Findings suggest the Heat Index could be used to assess heat stress exposures and to set occupational exposure limits for hot environments in the absence of high radiant heat.