NOAA Technical Memorandum ERL ESG-15 THE OPERATIONAL METEOROLOGY OF CONVECTIVE WEATHER VOLUME II: STORM SCALE ANALYSIS Charles A. Doswell III Environmental Sciences Group Boulder, Colorado April 1985 2012 e-book version Edition 1 (9/3/2012) [Draft version 1] TIM VASQUEZ Weather Graphics / www.weathergraphics.com Editing & Layout LEE McDERMOT Scanning & OCR NATIONAL OCEANIC AND Environmental Research noaa ATMOSPHERIC ADMINISTRATION Laboratories PREFACE CONVECTIVE WEATHER: VOLUME II (2012 EDITION) Like any written document in science, this Technical Memorandum published in 1985 [“The Operational Meteorology of Convective Weather: Volume II: Storm Scale Analysis,” NOAA Tech. Memo. NWS ESG-15] becomes increasingly obsolete as it ages. This document was begun while I was working in my first post-doctoral employment at what was then called the National Severe Storms Forecast Center (NSSFC), in Kansas City, MO. Given the time between starting the writing and the publication of the final manuscript after I had moved to the Weather Research Program in Boulder, CO, in late 1982 , it represents my understanding of the “storm scale” meteorology of severe convective storms as it was in 1984. This writing of this volume was done about a decade after what I call the “1970s revolution” in severe storms research, a scientific revolution driven by three elements that appeared in the early 1970s: 1) research Doppler radars, 2) the inception of scientific storm chasing, and 3) the development of 3-dimensional computer-based numerical models of deep convection. The results of this revolution were coming to be used in various operational applications and it was evident that a lot of ideas developed in the research world needed to be introduced in an understandable way (i.e., without much mathematics) to the operational community. Originally, it was planned that this document was to be written by my friend and NSSFC colleague, Les Lemon, but circumstances didn’t permit him to do so and I was recruited to finish this companion volume to the first Technical Memorandum I had published in 1982 [“The Operational Meteorology of Convective Weather: Volume I: Operational Mesoanalysis,” NOAA Tech. Memo. NWS NSSFC-5]. A third volume presenting application concepts and case studies was scheduled to be written but never was completed. As of writing this foreword in the late summer of 2012, numerous new contributions to our scientific understanding of severe storms have been made that have altered our way of thinking about storm scale processes since late 1984 - too numerous to mention here. Many important new findings have come from the field observational campaigns under the banner of the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX-1 in 1994/95 and VORTEX-2 in 2009/10). Research on the data from VORTEX-2 is still underway as I write this, with the prospect of even more revisions to our understanding on the horizon. Although some aspects of the contents of this volume remain valid today, a reader interested in an up-to-date understanding of severe storms meteorology would need to review a considerable amount of scientific literature, some of which might be too technical for the non-meteorologist to grasp. Therefore, readers of this work are encouraged to see it not as a comprehensive understanding of severe convective storm science, but rather as a historical snapshot of my personal understanding of that science in 1984. I hope that will still be of value to non-specialist readers. Perhaps someone else will choose to provide an updated version of this Tech. Memo. in the future. Science is always a moving target, which complicates the efforts of anyone hoping to explain it to an audience that includes non-specialists. Some people see that as a problem, but I consider it to be one of the reasons I’ve remained excited about being a scientist for the duration of my professional career, right up to the present moment. To have contributed to the advance of scientific understanding, even in a small way, is a great privilege. It is also a great honor that my published work remains of interest long after it has been superseded by newer research. I hope you will enjoy reading it even a tenth as much as I enjoyed learning it and writing about it! My thanks to my friend Tim Vasquez for his efforts on behalf of making a PDF version of this document available. All the hard copies I once had to distribute are gone, and the document has not been reprinted. I want to thank all my colleagues over the years for helping me to learn and benefit from their insights into the subject of this volume. These are far too numerous to mention them all, but I especially want to thank Les Lemon for his immense contributions to the science of severe storms, his enthusiasm for the project that resulted in these documents, and his enduring friendship. Drs. Joseph Schaefer (Vol. I) and Robert A. Maddox (Vol. II) were responsible for the eventual publication of these manuscripts, and both contributed significantly to any scientific insights I might have. Chuck Doswell September 2, 2012 ii FOREWORD BY THE EDITOR CONVECTIVE WEATHER: VOLUME II (2012 EDITION) Charles (Chuck) Doswell’s series The Operational Meteorology of Convective Weather attracted considerable notice among forecasters when it was released in the 1980s and rapidly found its way to forecast desks. Though severe weather forecasting has advanced considerably since then and meteorologists have a whole new arsenal of tools available, there is still consistent demand for this book, and supplies dried up about 10 years ago. In 2000 I released “Volume I: Operational Mesoanalysis” (1982) in PDF format, having converted it to a full-text scan to make it fully searchable. That left only “Volume II: Storm Scale Analysis”. That said, a Volume III, is mentioned in this document, but it does not exist since Chuck had been unable to find the time to begin it. Unfortunately time constraints and the much larger size of Volume II made this a difficult job. I made some progress in 2007, but had to shelve it again as my scanner was unbearably slow and other commitments soon eclipsed the project. Finally In January 2012 I was contacted by Lee McDermot, a former U.S. Air Force forecaster who served at Loring AFB in the late 1980s and early 1990s. He was interested in reviving the project, and backed up his enthusiasm by promising to send me fully scanned and OCR’d copies of Volume II. He followed through on this. The quality of the scans and the OCR output was impressive. Lee’s scanning software was also able to render a machine-made PDF of Volume II, but because of the significance of this tech memo series, I felt we needed to create a replica. Preserving a replica of a noteworthy scientific work should entail a commitment to accuracy and the placement of every single word and diagram on the page where it was originally found to allow proper citation. For historical sake, it should also recreate the “feel and texture” of the original work, so I used the IBM Selectric typewriter font found in the original. All of this was composed in Adobe InDesign CS4, and a copy of this “raw” project is available on the weathergraphics.com download page, sans fonts. Why go through all this trouble when a bunch of page scans can be rapidly collated into a PDF document (i.e. an “image PDF”)? On the fast/cheap/good triangle (in which you can have only one!) that is the fast and cheap way to do it. The text is not extracted, meaning the content cannot be searched or copy/pasted and Internet search engines can’t integrate the text into the body of online literature. These are major disadvantages. Ironically, last week while digging around in NOAA’s Document Rescue website I found that NOAA had scanned this document in May 2011 (see the URL on the next page), but it is merely an image PDF, as described above. And of course, it lacks Chuck’s new preface. Though severe weather research has progressed tremendously since the 1980s, most of the resources available to forecasters are still written for an academic or research audience and there are few publications which distill technical knowledge directly to the forecast desk. Because of this, the Operational Meteorology of Convective Weather series has aged quite well and will still provide valuable insights for forecasters, especially if Chuck’s earlier comments are taken into perspective. Many thanks to Lee McDermot for getting us to the finish line after 12 years on the drawing board, and to Chuck Doswell of course for his enthusiasm and support. Tim Vasquez August 31, 2012 iii When using a wide-screen monitor and Adobe Acrobat, this document is best viewed using View > Page Display > Two Page View. This document is maintained at http://www.weathergraphics.com and will be revised for any typesetting or proofreading errors that are found. An official image PDF version of this document (not searchable) exists at: http://docs.lib.noaa.gov/noaa_documents/OAR/ERL_ESG/TM_ERL_ESG_15.pdf iv NOAA Technical Memorandum ERL ESG-15 THE OPERATIONAL METEOROLOGY OF CONVECTIVE WEATHER VOLUME II: STORM SCALE ANALYSIS Charles A. Doswell III Weather Research Program Environmental Sciences Group Boulder, Colorado April 1985 UNITED STATES NATIONAL OCEANIC AND Environmental Research DEPARTMENT OF COMMERCE ATMOSPHERIC ADMINISTRATION Laboratories Malcolm Baldridge, Vernon E. Derr, Secretary Director v NOTICE Mention of a commercial company or product does not constitute an endorsement by NOAA Environmental Research Laboratories. Use for publicity or advertising purposes of information from this publication concerning proprietary products or the tests of such products is not authorized.