WARNING APPLICATIONS RESEARCH

Manross, K. L., T. M. Smith, J. T. Ferree, G. J. Stumpf, 2008: An on-demand user interface for requesting multi-radar, multi-sensor time accumulated products to support severe weather verification. Extended Abstracts, 23rd Conference on Interactive Information Processing Systems, New Orleans, LA, USA, AMS, P2.13.

NSSL has a long history of developing radar based applications and algorithms intended to aid forecasters in warning decision making. With the advent of the WDSSII system, new and more robust algorithms are being developed in short amounts of time. Thanks to the GIS-based Google Earth application, NSSL has been able to display real-time algorithm output via the World Wide Web for feedback on these algorithms. As a result, many of these algorithms have not only proven useful and accurate, but also popular, particularly in short-term post-event storm survey and verification situations. Time accumulated Maximum Expected Size of Hail ("MESH") and time accumulated radar detected maximum low-altitude rotational shear ("Rotation Tracks") are two products that seem to be particularly useful. The latter has been used to aid forecasters in tornado damage surveys performed by National Weather Service (NWS) personnel at numerous Weather Service Forecast Offices. Emergency managers may also find these plots useful for disaster response.

Currently these data are continuously being produced on the CONUS scale and are stored in a short term archive (up to one week). For specific events, or by request, the data can be manually reprocessed for smaller regions and short time scales and are occasionally archived indefinitely. A recently funded proposal has allowed for automated, on-demand requests of these products by end-users. Forecasters may specify region-specific GIS-encoded data for requested time periods using a web-based graphical user interface. This paper details this process as well as explaining the user interface.

Available online at ://http://ams.confex.com/ams/88Annual/techprogram/paper_134621.htm.

Scharfenberg, K., T. M. Smith, C. Legett, K. L. Manross, K. L. Ortega, A. G. Kolodziej, 2008: NSSL's prototype enhanced severe thunderstorm database. Extended Abstracts, 24th Conf. on IIPS, New Orleans, LA, USA, Amer. Meteor. Soc., 5C.1.

Smith, T. M., V. Lakshmanan, 2008: Real-time and recent historical weather data in Google Earth. Extended Abstracts, 23rd Conference on Interactive Information Processing Systems, New Orleans, LA, USA, AMS, 9B.6.

The National Severe Storms Laboratory (NSSL) utilizes Google Earth as one of several ways to share experimental severe weather products with other researchers and operational meteorologists for evaluation and feedback. A variety of multi-sensor severe weather products are generated by NSSL and shared to Google Earth users via the internet at http://wdssii.nssl.noaa.gov. These products include spatially gridded fields of Vertically Integrated Liquid, Maximum Expected Hail Size, tracks of circulations derived from Doppler velocity data, composite reflectivity, and 30-to-60 minute forecast reflectivity fields, among others. These products, which have a spatial resolution of approximately 1 km by 1 km, are generated every one to five minutes within the Warning Decision Support System – Integrated Information (WDSS-II). The WDSS-II system provides the images in GeoTIFF format which may be imported into most Geographic Information Systems software including virtual globes such as Google Earth.

During the first two years these data have been provided on the internet, they have been used to improve the verification of severe weather events as well as in disaster response and post-event damage assessments. This presentation focuses on the scientific and educational uses of virtual globes to interrogate real-time and archived severe weather products.

Available online at ://http://http://ams.confex.com/ams/88Annual/techprogram/paper_134923.htm.

Scharfenberg, K. A., K. L. Elmore, T. J. Schuur, C. Legett, 2007: Analysis of dual-pol WSR-88D base data collected during three significant winter storms. Preprints, 31st Intl. Conf. on Radar Meteor., Cairns, Australia, Amer. Meteor. Soc., CD-ROM, P10.10.

Base data from a dual-pol WSR-88D radar collected during three significant winter storms in Oklahoma are examined. These cases (29-30 November 2006, 12-14 January 2007, and 20 January 2007) were chosen due to concurrent collection of high-resolution surface precipitation type reports near the radar (see paper by Elmore, Scharfenberg, and Legett). Large temporal and spatial variabilities in precipitation types were observed during these events as revealed by the surface reports. This paper will focus on radar data collected during these periods of large variability. Associating the evolution of the radar data and the surface reports is critical for future enhancements to automated hydrometeor classification and to successful forecast decision-making during winter storms.

Available online at ://http://ams.confex.com/ams/pdfpapers/123618.pdf.

Scharfenberg, K. A., D. W. Burgess, M. J. Istok, K. L. Manross, R. Murnan, P. T. Schlatter, 2007: Product development and evaluation for the dual-pol WSR-88D radar. Preprints, 31st Intl. Conf. on Radar Meteor., Cairns, Australia, Amer. Meteor. Soc., CD-ROM, 10.2.

The United States' WSR-88D weather radar network is expected to be upgraded to include dual-polarimetric capabilities over the next several years. This upgrade is presumed to improve echo classification, precipitation rate estimation, and overall data quality. Numerous dual-pol WSR-88D data sets from a prototype radar in Norman, Oklahoma have been collected. Seven sample dual-pol WSR-88D datasets were distributed to operational users of WSR-88D radar data throughout the United States. These cases were chosen to cover a variety of high-impact weather events, including significant winter storms, severe thunderstorms, mixed precipitation phases, and heavy rainfall. Low-to-moderate-impact weather events were also chosen, including light to moderate rain and light snow events. Finally, the data were chosen to include meteorological echoes at various ranges from the radar as well as non-meteorological echoes. The evaluators were asked to provide feedback on the sample dual-pol base products (differential reflectivity, correlation coefficient, differential phase shift, and specific differential phase shift) and associated algorithms (hydrometeor classification, filtered reflectivity, and quantitative precipitation estimation). The results of the collected feedback are discussed in this paper, along with implications for operational forecasting, warning decision-making, product visualization, and training requirements.

Available online at ://http://ams.confex.com/ams/pdfpapers/123618.pdf.

Smith, T. M., P. L. Heinselman, D. Priegnitz, 2007: Characteristics of microburst events observed with the National Weather Radar Testbed phased array radar. Preprints, 23rd Conference on Interactive Information Processing Systems, San Antonio, TX, USA, AMS, CD-ROM, 7.8.

Microbursts are small-scale (< 4 km diameter) outflows induced by strong downdrafts in thunderstorms that frequently cause damage to property and are a hazard to aviators. Many severe microbursts originate from storm cells that form in regions of moderate-to-high Convective Available Potential Energy (CAPE), weak environmental shear, and environments that are highly unstable to downdraft formation. These storm cells typically have a life cycle of 20-40 minutes, which makes them very difficult to predict.

Automated algorithms that analyze radar data and make short-term predictions for microburst events, as well as detecting low-altitude divergence signatures associated with their outflows, have been implemented for WSR-88D and TDWR systems. These applications rely on microburst “precursors” that may be observed at the higher altitudes of a storm shortly preceding the outflow at the surface to make short-lead-time forecasts of a microburst event. However, microburst events evolve rapidly, and because these radars typically only sample the upper portions of a storm once every 4 to 6 minutes (depending on scanning strategy), they may not sample key precursor features aloft or the near-surface outflow.

This presentation examines damage-producing severe microburst events that occurred in Central Oklahoma during July 2006 that were observed with the National Weather Radar Testbed (NWRT) Phased Array Radar (PAR). These storms formed within 50 km of the PAR site and were sampled with a temporal resolution of 15 to 30 seconds. We will compare the PAR observations of the storms with the KTLX WSR-88D, OKC TDWR, and multi-radar, multi-sensor information from the Warning Decision Support System – Integrated Information.

Available online at ://http://ams.confex.com/ams/pdfpapers/120074.pdf.

Smith, T. M., K. L. Ortega, A. G. Kolodziej, 2007: Enhanced, high-density severe storm verification. Preprints, 23rd Conference on Interactive Information Processing Systems, San Antonio, TX, USA, AMS, CD-ROM, 4B.3.

The Severe Hail Verification Experiment (SHAVE) was conducted during May through August of 2006. Researchers in SHAVE combined radar and environmental information available from the National Severe Storms Laboratory's Warning Decision Support System – Integrated Information (WDSS-II) with geographic information available in Google Earth and other sources. This information was used to identify locations to make targeted telephone calls to the public in regions where storms occurred within minutes of an event in order to collect information about the occurrence, size, and duration of hail. During the experiment, hail swaths from severe thunderstorms were documented at a much higher spatial and temporal resolution than is available in the National Climate Data Center's Storm Data publication and in National Weather Service (NWS) local storm report products.

The presentation shows results from SHAVE and compares the independently collected, high-resolution data with traditional NWS verification data for hail, and discusses the uncertainties associated with both data sets. We discuss the benefits of the improved verification data and their implications for warning verification and future changes in the NWS warning paradigm, such as “warning polygons” and probabilistic threat area warnings. We also consider improvements to the data collection methodologies and the expansion of the experiment in 2007 to include the analysis of severe wind events and other threats.

Available online at ://http://ams.confex.com/ams/pdfpapers/120091.pdf.

Witt, A., 2007: Performance of two velocity dealiasing algorithms on Terminal Doppler Weather Radar data. Preprints, 33rd Conference on Radar Meteorology, Cairns, Australia, American Meteorological Society, CD-ROM, P13A.14.

Manross, K. L., J. G. LaDue, 2006: New Features of the VCPExplorer: Simulated Precipitation. Extended Abstracts, 22nd International Conference on Interactive Information Processing Systems for Meteorology, Oceanography, and Hydrology, Atlanta, GA, USA, American Meteorological Society, CD-ROM, 2.11. [Available from Kevin L. Manross, NSSL, 1313 Halley Circle, Norman, OK, USA, 73069.]

The VCPExplorer is an instructional tool that aides in the visualization of radar scanning strategies, including radar beam propagation path relative to terrain, and radar algorithm dependence on volume coverage pattern (VCP). The VCPExplorer has been used in the Warning Decision Training Branch's (WDTB) Advanced Warning Operations Course (AWOC) and has been upgraded with several new features to simulate radar sampling issues of precipitation. Among the new features are radar estimated rainfall. The user can modify several parameters including ZR relationship, VCP, and reflectivity profile and compare the radar estimated (based on VCP and terrain-based hybrid scan) rainfall to the "true" (based on radar reflectivity at the Earth's surface) rainfall. Other new features include simulated "bright-banding" and sub-cloud evaporation effects on radar reflectivity.

Available online at ://http://ams.confex.com/ams/Annual2006/techprogram/paper_104425.htm.

Ortega, K. L., T. M. Smith, G. J. Stumpf, 2006: Verification of multi-sensor, multi-radar hail diagnosis techniques. Preprints, Symposium on the Challenges of Severe Convective Storms, Atlanta, GA, USA, American Meteorological Society, CD-ROM, P1.1.

Ortega, K. L., T. M. Smith, K. A. Scharfenberg, 2006: An analysis of thunderstorm hail fall patterns in the Severe Hail Verification Experiment. Preprints, 23rd Conference on Severe Local Storms, St. Louis, MO, USA, AMS, CD-ROM, P2.4.

Available online at ://http://ams.confex.com/ams/23SLS/techprogram/paper_115441.htm.

Scharfenberg, K. A., 2006: Development and testing of a dual-pol-based surface precipitation type algorithm. Preprints, 12th Conf. on Aviation, Range, and Aerospace Meteor., Atlanta, GA, USA, Amer. Meteor. Soc., CD-ROM, P6.2.

An algorithm to integrate data from surface temperature sensors, numerical weather prediction model thermodynamic output, and dual-polarimetric radar hydrometeor classification algorithm output and produce a surface precipitation type product is described. Results from initial tests on a few archived cases are presented. Although sufficient verification data sets are not yet available, this technique shows promise in accurately depicting regions of freezing rain, snow, and rain at the surface, aiding aviation ground operations during winter storms.

Smith, T. M., V. Lakshmanan, 2006: Utilizing Google Earth as a GIS platform for weather applications. Preprints, 22nd Conference on Interactive Information Processing Systems, Atlanta, GA, USA, AMS, CD-ROM, 8.2.

Available online at ://http://ams.confex.com/ams/Annual2006/techprogram/paper_104847.htm.

Smith, T. M., K. L. Ortega, K. A. Scharfenberg, K. M. Manross, A. Witt, 2006: The Severe Hail Verfication Experiment. Preprints, 23rd Conference on Severe Local Storms, St. Louis, MO, USA, AMS, CD-ROM, 5.3.

Available online at ://http://ams.confex.com/ams/23SLS/techprogram/paper_115436.htm.

Manross, K. L., J. G. LaDue, G. Stumpf, 2005: The Volume Coverage Pattern Explorer: A new tool for visualizing radar beam paths. Preprints, 21st International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology, San Diego, CA, USA, American Meteorological Society, CD-ROM, 5.5.

Ortega, K. L., T. M. Smith, G. J. Stumpf, J. Hocker, L. López, 2005: A comparison of multi-sensor hail diagnosis techniques. Preprints, 21st International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology, San Diego, CA, USA, American Meteorological Society, P1.11.

Scharfenberg, K. A., T. M. Smith, G. J. Stumpf, 2005: The testing of NSSL multi-sensor applications and data from prototype platforms in NWS forecast operations. Preprints, 21st Conference on Weather Analysis and Forecasting, Washington, DC, USA, American Meteorological Society, 6A.2.

Scharfenberg, K. A., V. Lakshmanan, S. E. Giangrande, 2005: Development and testing of polarimetric radar applications in WDSS-II. Preprints, 21st International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology, San Diego, CA, USA, American Meteorological Society, CD-ROM, 5.1.

Scharfenberg, K. A., D. J. Miller, T. J. Schuur, P. T. Schlatter, S. E. Giangrande, V. M. Melnikov, D. W. Burgess, D. L. Andra, Jr., M. P. Foster, J. M. Krause, 2005: The Joint Polarization Experiment: Polarimetric radar in forecasting and warning decision-making. Weather and Forecasting, 20, 775-788.

To test the utility and added value of polarimetric radar products in an operational environment, data from the Norman, Oklahoma (KOUN), polarimetric Weather Surveillance Radar-1988 Doppler (WSR-88D) were delivered to the National Weather Service Weather Forecast Office (WFO) in Norman as part of the Joint Polarization Experiment (JPOLE). KOUN polarimetric base data and algorithms were used at the WFO during the decision-making and forecasting processes for severe convection, flash floods, and winter storms. The delivery included conventional WSR-88D radar products, base polarimetric radar variables, a polarimetric hydrometeor classification algorithm, and experimental polarimetric quantitative precipitation estimation algorithms. The JPOLE data collection, delivery, and operational demonstration are described, with examples of several forecast and warning decision-making successes. Polarimetric data aided WFO forecasters during several periods of heavy rain, numerous large-hail-producing thunderstorms, tornadic and nontornadic supercell thunderstorms, and a major winter storm. Upcoming opportunities and challenges associated with the emergence of polarimetric radar data in the operational community are also described.

Scharfenberg, K. A., K. L. Elmore, E. Forren, V. Melnikov, D. S. Zrnic, 2005: Estimating the impact of a 3-dB sensitivity loss on WSR-88D data. Preprints, 32nd Conf. on Radar Meteorology, Albuquerque, NM, USA, Amer. Meteor. Soc., CD-ROM, P12R.9.

The planned upgrade of the WSR-88D network to include dual-polarimetric capabilities is expected to result in a loss of about 3 dB in sensitivity per channel. In order to better estimate the impact of this sensitivity loss, case study and real-time simulations were performed.

Algorithm products and base data from six archive WSR-88D cases were examined. The proportion of reflectivity samples lost upon desensitization was calculated, and the visibility of important meteorological features and velocity dealiasing errors before and after the desensitization were noted. Changes in the outputs of the echo top, hail detection, and legacy mesocyclone algorithms were observed. Changes to the output of the VAD wind profile (VWP) algorithm were measured. These results are presented.

In addition, a 3 dB higher threshold then usual was applied to KTLX WSR-88D data to simulate the signal loss. This data was then made available to National Weather Service forecasters for a side-by-side evaluation during the spring 2005 convective season. Forecaster feedback was compiled to estimate the impact of the sensitivity loss on situation awareness and decision-making, and these results are discussed.

An overview of proposed mitigation techniques to recover some of the lost velocity information is presented.

Available online at ://http://ams.confex.com/ams/pdfpapers/96931.pdf.

Smith, T. M., G. J. Stumpf, 2005: Multi-sensor storm cell identification and analysis. Preprints, 21st International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology, San Diego, CA, USA, American Meteorological Society, P1.10.

Witt, A., R. A. Brown, V. Lakshmanan, 2005: Real-time calculation of horizontal winds using multiple Doppler radars: A new WDSS-II module. Preprints, 32nd Conference on Radar Meteorology, Albuquerque, NM, USA, Amer. Meteor. Soc., CD-ROM, P8R.7.

Manross, K. L., R. J. Trapp, G. J. Stumpf, 2004: WSR-88D radar characteristics of quasi-linear convective system tornadoes using the NSSL Severe Storm Analysis Program. Preprints, 22nd Conference on Severe Local Storms, Hyannis, MA, USA, American Meteorological Society, CD-ROM, 8B.2.

Scharfenberg, K. A., D. J. Miller, P. Heinselman, D. L. Andra Jr., M.P. Foster, 2004: Highlights from the Joint Polarization Experiment operational demonstration. Preprints, 20th Conference on Weather Analysis and Forecasting, Seattle, WA, USA, American Meteorological Society, XX-XX.

Scharfenberg, K. A., P. T. Schlatter, D. J. Miller, C. A. Whittier, 2004: The use of the "ZDRcolumn signature in short-term thunderstorm forecasts. Preprints, 11th Conference on Aviation, Range, and Aerospace Meteorology, Hyannis, MA, USA, American Meteorological Society, CD-ROM, P5.5.

Scharfenberg, K. A., V. Lakshmanan, 2004: The use of NWP data in polarimetric hydrometeor classification. Preprints, 11th Conference on Aviation, Range, and Aerospace Meteorology, Hyannis, MA, USA, American Meteorological Society, CD-ROM, P5.7.

Scharfenberg, K. A., D. J. Miller, D. L. Andra Jr., M. P. Foster, 2004: Overview of spring 2004 WDSS-II demonstration at WFO Norman. Preprints, 22nd Conference on Severe Local Storms, Hyannis, MA, USA, American Meteorological Society, CD-ROM, 8B.7.

Smith, T. M., K. L. Elmore, S. A. Dulin, 2004: A damaging downburst prediction and detection algorithm for the WSR-88D. Weather and Forecasting, 19, 240-250.

Manross, K. L., R. J.Trapp, G. J.Stumpf, 2003: WSR-88D radar characteristics of quasi-linear convective system tornadoes using the NSSL severe storm analysis program. Preprints, 31st International Conference on Radar Meteorology, Seattle, WA, USA, American Meteorological Society, P2C.4.

Scharfenberg, K. A., E. Maxwell, 2003: Operational use of a hydrometeor classification algorithm to detect the snow melting level. Preprints, 31st International Conference on Radar Meteorology (Vol. II), Seattle, WA, USA, American Meteorological Society, 639-641.

Scharfenberg, K. A., D. L. Andra Jr., M. P. Foster, 2003: Operational uses of polarimetric radar in severe local storm prediction. Preprints, 31st International Conference on Radar Meteorology (Vol. II), Seattle, WA, USA, American Meteorological Society, 632-634.

Scharfenberg, K. A., 2003: Polarimetric radar signatures in microburst-producing thunderstorms. Preprints, 31st International Conference on Radar Meteorology (Vol. II), Seattle, WA, USA, American Meteorological Society, 581-584.

Smith, T. M., K. L. Elmore, G. J. Stumpf, V. Lakshmanan, 2003: Detection of rotation and boundaries using two-dimensional, local, linear least squares estimates of velocity derivatives. Preprints, 31st International Conference on Radar Meteorology, Seattle, WA, USA, American Meteorological Society, 310-313.

Smith, T. M., K. L. Elmore, G. J. Stumpf, V. Lakshmanan, 2003: The operational use of rotation and divergence fields derived from Doppler radial velocities. 18th Annual Meeting of the National Weather Association, Jacksonville, FL, USA, National Weather Association, XX-XX.

Smith, T. M., G. J. Stumpf, K. L. Manross, C. Thomas, 2003: Warning Decision Support System - Integrated Information (WDSS-II). Part I: Multiple-sensor severe weather applications development at NSSL during 2002. Preprints, 19th International Conference on Interactive Information Processing Systems for Meteorology, Oceanography, and Hydrology (IIPS), LongBeach, CA, USA, American Meteorological Society, CD-ROM, 14.8.