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Lans P. Rothfusz

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Lans P. Rothfusz

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A technique utilizing stereo-photogrammetry of neutrally buoyant bubbles in a tornado vortex chamber (TVC) is described. This technique is advantageous over others inasmuch as it is nonintrusive and does not require the compositing of many individual fixed-point velocity samples. A particular TVC experiment is used to demonstrate the technique.

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Lans P. Rothfusz and Douglas K. Lilly

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This paper extends the earlier preliminary results of a laboratory simulation of a mesocyclonic circulation with an embedded tornadic vortex, produced by a vertically veering but nonrotating inflow with high helicity. Higher quality velocity measurements are performed which allow more detailed quantitative analyses, and are interpreted with the aid of a secondary flow model. The vortex is produced by vertical eddy transport of angular momentum generated by a helical secondary flow. The positive angular momentum on the right side of the inflow remains at low levels until it is stretched in the vortex core, while the negative angular momentum on the left side is lifted and carried out of the circulation.

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Lans P. Rothfusz, Melvin R. McLaughlin, and Stephen K. Rinard

The 1996 Centennial Olympic Games in Atlanta, Georgia, received weather support from the National Weather Service (NWS). The mandate to provide this support gave the NWS an unprecedented opportunity to employ in an operational setting several tools and practices similar to those planned for the “modernized” era of the NWS. The project also provided a glimpse of technology and practices not planned for the NWS modernization, but that might be valuable in the future. The underlying purpose of the project was to protect the life and property of the two million spectators, athletes, volunteers, and officials visiting and/or participating in the games. While there is no way to accurately account for lives and property that were protected by the NWS support, the absence of weather-related deaths, significant injuries, and damaged property during the games despite an almost daily occurrence of thunderstorms, high temperatures, and/or rain indicates that the project was a success. In fact, popular perception held that weather had no effect on the games. The 2000+ weather bulletins issued during the 6-week support period suggest otherwise. The authors describe the many facets of this demanding and successful project, with special attention given to aspects related to operational forecasting. A postproject survey completed by the Olympics forecasters, feedback provided by weather support customers, and experiences of the management team provide the bases for project observations and recommendations for future operational forecasting activities.

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Kimberly L. Elmore, Z. L. Flamig, V. Lakshmanan, B. T. Kaney, V. Farmer, Heather D. Reeves, and Lans P. Rothfusz

The Weather Service Radar-1988 Doppler (WSR-88D) network within the United States has recently been upgraded to include dual-polarization capability. Among the expectations that have resulted from the upgrade is the ability to discriminate between different precipitation types in winter precipitation events. To know how well any such algorithm performs and whether new algorithms are an improvement, observations of winter precipitation type are needed. Unfortunately, the automated observing systems cannot discriminate between some of the more important types. Thus, human observers are needed. Yet, to deploy dedicated human observers is impractical because the knowledge needed to identify the various precipitation types is common among the public. To most efficiently gather such observations would require the public to be engaged as citizen scientists using a very simple, convenient, nonintrusive method. To achieve this, a simple “app” called mobile Precipitation Identification Near the Ground (mPING) was developed to run on “smart” phones or, more generically, web-enabled devices with GPS location capabilities. Using mPING, anyone with a smartphone can pass observations to researchers at no additional cost to their phone service or to the research project. Deployed in mid-December 2012, mPING has proven to be not only very popular, but also capable of providing consistent, accurate observational data.

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Lans P. Rothfusz, Russell Schneider, David Novak, Kimberly Klockow-McClain, Alan E. Gerard, Chris Karstens, Gregory J. Stumpf, and Travis M. Smith

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Recommendations by the National Research Council (NRC), the National Institute of Standards and Technology (NIST), and Weather-Ready Nation workshop participants have encouraged the National Oceanic and Atmospheric Administration (NOAA) and the broader weather enterprise to explore and expand the use of probabilistic information to convey weather forecast uncertainty. Forecasting a Continuum of Environmental Threats (FACETs) is a concept being explored by NOAA to address those recommendations and also potentially shift the National Weather Service (NWS) from (primarily) teletype-era, deterministic watch–warning products to high-resolution, probabilistic hazard information (PHI) spanning periods from days (and longer) to within minutes of high-impact weather and water events. FACETs simultaneously i) considers a reinvention of the NWS hazard forecasting and communication paradigm so as to deliver multiscale, user-specific probabilistic guidance from numerical weather prediction ensembles and ii) provides a comprehensive framework to organize the physical, social, and behavioral sciences, the technology, and the practices needed to achieve that reinvention. The first applications of FACETs have focused on thunderstorm phenomena, but the FACETs concept is envisioned to extend to the attributes of any environmental hazards that can be described probabilistically (e.g., winter, tropical, and aviation weather). This paper introduces the FACETs vision, the motivation for its creation, the research and development under way to explore that vision, its relevance to operational forecasting and society, and possible strategies for implementation.

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Christopher D. Karstens, Greg Stumpf, Chen Ling, Lesheng Hua, Darrel Kingfield, Travis M. Smith, James Correia Jr., Kristin Calhoun, Kiel Ortega, Chris Melick, and Lans P. Rothfusz

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A proposed new method for hazard identification and prediction was evaluated with forecasters in the National Oceanic and Atmospheric Administration Hazardous Weather Testbed during 2014. This method combines hazard-following objects with forecaster-issued trends of exceedance probabilities to produce probabilistic hazard information, as opposed to the static, deterministic polygon and attendant text product methodology presently employed by the National Weather Service to issue severe thunderstorm and tornado warnings. Three components of the test bed activities are discussed: usage of the new tools, verification of storm-based warnings and probabilistic forecasts from a control–test experiment, and subjective feedback on the proposed paradigm change. Forecasters were able to quickly adapt to the new tools and concepts and ultimately produced probabilistic hazard information in a timely manner. The probabilistic forecasts from two severe hail events tested in a control–test experiment were more skillful than storm-based warnings and were found to have reliability in the low-probability spectrum. False alarm area decreased while the traditional verification metrics degraded with increasing probability thresholds. The latter finding is attributable to a limitation in applying the current verification methodology to probabilistic forecasts. Relaxation of on-the-fence decisions exposed a need to provide information for hazard areas below the decision-point thresholds of current warnings. Automated guidance information was helpful in combating potential workload issues, and forecasters raised a need for improved guidance and training to inform consistent and reliable forecasts.

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Joseph T. Schaefer, James P. Travers, Thomas A. Heffner, A. Dale Eubanks, Armando L. Garza, Lans P. Rothfusz, Walter A. Rogers, Sylvia K. Graff, James T. Skeen, Kenneth Haydu, and M. Lee Harrisons

The National Weather Service sponsored a workshop on aviation weather on 10–12 December 1991, in Kansas City, Missouri. The theme of the workshop was the improvement of service to the aviation community through the application of technology and advanced forecast techniques. The 150-plus people who attended the workshop included a cross section of operational forecasters, pilots, research meteorologists, and representatives of the aviation industry. The workshop included sessions on user requirements, operational procedures, and the impacts of new technology on the forecast products. There were also four “hands-on” laboratory sessions where participants produced various types of aviation weather products. The interaction between the user community and working-level forecasters made the workshop a unique event.

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Christopher D. Karstens, James Correia Jr., Daphne S. LaDue, Jonathan Wolfe, Tiffany C. Meyer, David R. Harrison, John L. Cintineo, Kristin M. Calhoun, Travis M. Smith, Alan E. Gerard, and Lans P. Rothfusz

Abstract

Providing advance warning for impending severe convective weather events (i.e., tornadoes, hail, wind) fundamentally requires an ability to predict and/or detect these hazards and subsequently communicate their potential threat in real time. The National Weather Service (NWS) provides advance warning for severe convective weather through the issuance of tornado and severe thunderstorm warnings, a system that has remained relatively unchanged for approximately the past 65 years. Forecasting a Continuum of Environmental Threats (FACETs) proposes a reinvention of this system, transitioning from a deterministic product-centric paradigm to one based on probabilistic hazard information (PHI) for hazardous weather events. Four years of iterative development and rapid prototyping in the National Oceanic and Atmospheric Administration (NOAA) Hazardous Weather Testbed (HWT) with NWS forecasters and partners has yielded insights into this new paradigm by discovering efficient ways to generate, inform, and utilize a continuous flow of information through the development of a human–machine mix. Forecasters conditionally used automated object-based guidance within four levels of automation to issue deterministic products containing PHI. Forecasters accomplished this task in a timely manner while focusing on communication and conveying forecast confidence, elements considered necessary by emergency managers. Observed annual increases in the usage of first-guess probabilistic guidance by forecasters were related to improvements made to the prototyped software, guidance, and techniques. However, increasing usage of automation requires improvements in guidance, data integration, and data visualization to garner trust more effectively. Additional opportunities exist to address limitations in procedures for motion derivation and geospatial mapping of subjective probability.

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