A Revised Tornado Definition and Changes in Tornado Taxonomy
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
From Improving Tornado Warnings: from Observation to Forecast
Improving Tornado Warnings: from Observation to Forecast John T. Snow Regents’ Professor of Meteorology Dean Emeritus, College of Atmospheric and Geographic Sciences, The University of Oklahoma Major contributions from: Dr. Russel Schneider –NOAA Storm Prediction Center Dr. David Stensrud – NOAA National Severe Storms Laboratory Dr. Ming Xue –Center for Analysis and Prediction of Storms, University of Oklahoma Dr. Lou Wicker –NOAA National Severe Storms Laboratory Hazards Caucus Alliance Briefing Tornadoes: Understanding how they develop and providing early warning 10:30 am – 11:30 am, Wednesday, 21 July 2010 Senate Capitol Visitors Center 212 Each Year: ~1,500 tornadoes touch down in the United States, causing over 80 deaths, 100s of injuries, and an estimated $1.1 billion in damages Statistics from NOAA Storm Prediction Center Supercell –A long‐lived rotating thunderstorm the primary type of thunderstorm producing strong and violent tornadoes Present Warning System: Warn on Detection • A Warning is the culmination of information developed and distributed over the preceding days sequence of day‐by‐day forecasts identifies an area of high threat •On the day, storm spotters deployed; radars monitor formation, growth of thunderstorms • Appearance of distinct cloud or radar echo features tornado has formed or is about to do so Warning is generated, distributed Present Warning System: Warn on Detection Radar at 2100 CST Radar at 2130 CST with Warning Thunderstorms are monitored using radar A warning is issued based on the detected and -
A Study of Synoptic-Scale Tornado Regimes
Garner, J. M., 2013: A study of synoptic-scale tornado regimes. Electronic J. Severe Storms Meteor., 8 (3), 1–25. A Study of Synoptic-Scale Tornado Regimes JONATHAN M. GARNER NOAA/NWS/Storm Prediction Center, Norman, OK (Submitted 21 November 2012; in final form 06 August 2013) ABSTRACT The significant tornado parameter (STP) has been used by severe-thunderstorm forecasters since 2003 to identify environments favoring development of strong to violent tornadoes. The STP and its individual components of mixed-layer (ML) CAPE, 0–6-km bulk wind difference (BWD), 0–1-km storm-relative helicity (SRH), and ML lifted condensation level (LCL) have been calculated here using archived surface objective analysis data, and then examined during the period 2003−2010 over the central and eastern United States. These components then were compared and contrasted in order to distinguish between environmental characteristics analyzed for three different synoptic-cyclone regimes that produced significantly tornadic supercells: cold fronts, warm fronts, and drylines. Results show that MLCAPE contributes strongly to the dryline significant-tornado environment, while it was less pronounced in cold- frontal significant-tornado regimes. The 0–6-km BWD was found to contribute equally to all three significant tornado regimes, while 0–1-km SRH more strongly contributed to the cold-frontal significant- tornado environment than for the warm-frontal and dryline regimes. –––––––––––––––––––––––– 1. Background and motivation As detailed in Hobbs et al. (1996), synoptic- scale cyclones that foster tornado development Parameter-based and pattern-recognition evolve with time as they emerge over the central forecast techniques have been essential and eastern contiguous United States (hereafter, components of anticipating tornadoes in the CONUS). -
Hurricane Outer Rainband Mesovortices
Presented at the 24th Conference on Hurricanes and Tropical Meteorology, Ft. Lauderdale, FL, May 31 2000 EXAMINING THE PRE-LANDFALL ENVIRONMENT OF MESOVORTICES WITHIN A HURRICANE BONNIE (1998) OUTER RAINBAND 1 2 2 1 Scott M. Spratt , Frank D. Marks , Peter P. Dodge , and David W. Sharp 1 NOAA/National Weather Service Forecast Office, Melbourne, FL 2 NOAA/AOML Hurricane Research Division, Miami, FL 1. INTRODUCTION Tropical Cyclone (TC) tornado environments have been studied for many decades through composite analyses of proximity soundings (e.g. Novlan and Gray 1974; McCaul 1986). More recently, airborne and ground-based Doppler radar investigations of TC rainband-embedded mesocyclones have advanced the understanding of tornadic cell lifecycles (Black and Marks 1991; Spratt et al. 1997). This paper will document the first known dropwindsonde deployments immediately adjacent to a family of TC outer rainband mesocyclones, and will examine the thermodynamic and wind profiles retrieved from the marine environment. A companion paper (Dodge et al. 2000) discusses dual-Doppler analyses of these mesovortices. On 26 August 1998, TC Bonnie made landfall as a category two hurricane along the North Carolina coast. Prior to landfall, two National Oceanographic and Atmospheric Administration (NOAA) Hurricane Research Division (HRD) aircraft conducted surveillance missions offshore the Carolina coast. While performing these missions near altitudes of 3.5 and 2.1 km, both aircraft were required to deviate around intense cells within a dominant outer rainband, 165 to 195 km northeast of the TC center. On-board radars detected apparent mini-supercell signatures associated with several of the convective cells along the band. -
Kármán Vortex Street Energy Harvester for Picoscale Applications
Kármán Vortex Street Energy Harvester for Picoscale Applications 22 March 2018 Team Members: James Doty Christopher Mayforth Nicholas Pratt Advisor: Professor Brian Savilonis A Major Qualifying Project submitted to the Faculty of WORCESTER POLYTECHNIC INSTITUTE in partial fulfilment of the requirements for the degree of Bachelor of Science This report represents work of WPI undergraduate students submitted to the faculty as evidence of a degree requirement. WPI routinely publishes these reports on its web site without editorial or peer review. For more information about the projects program at WPI, see http://www.wpi.edu/Academics/Projects. Cover Picture Credit: [1] Abstract The Kármán Vortex Street, a phenomenon produced by fluid flow over a bluff body, has the potential to serve as a low-impact, economically viable alternative power source for remote water-based electrical applications. This project focused on creating a self-contained device utilizing thin-film piezoelectric transducers to generate hydropower on a pico-scale level. A system capable of generating specific-frequency vortex streets at certain water velocities was developed with SOLIDWORKS modelling and Flow Simulation software. The final prototype nozzle’s velocity profile was verified through testing to produce a velocity increase from the free stream velocity. Piezoelectric testing resulted in a wide range of measured dominant frequencies, with corresponding average power outputs of up to 100 nanowatts. The output frequencies were inconsistent with predicted values, likely due to an unreliable testing environment and the complexity of the underlying theory. A more stable testing environment, better verification of the nozzle velocity profile, and fine-tuning the piezoelectric circuit would allow for a higher, more consistent power output. -
Tornado Safety Q & A
TORNADO SAFETY Q & A The Prosper Fire Department Office of Emergency Management’s highest priority is ensuring the safety of all Prosper residents during a state of emergency. A tornado is one of the most violent storms that can rip through an area, striking quickly with little to no warning at all. Because the aftermath of a tornado can be devastating, preparing ahead of time is the best way to ensure you and your family’s safety. Please read the following questions about tornado safety, answered by Prosper Emergency Management Coordinator Kent Bauer. Q: During s evere weather, what does the Prosper Fire Department do? A: We monitor the weather alerts sent out by the National Weather Service. Because we are not meteorologists, we do not interpret any sort of storms or any sort of warnings. Instead, we pass along the information we receive from the National Weather Service to our residents through social media, storm sirens and Smart911 Rave weather warnings. Q: What does a Tornado Watch mean? A: Tornadoes are possible. Remain alert for approaching storms. Watch the sky and stay tuned to NOAA Weather Radio, commercial radio or television for information. Q: What does a Tornado Warning mean? A: A tornado has been sighted or indicated by weather radar and you need to take shelter immediately. Q: What is the reason for setting off the Outdoor Storm Sirens? A: To alert those who are outdoors that there is a tornado or another major storm event headed Prosper’s way, so seek shelter immediately. I f you are outside and you hear the sirens go off, do not call 9-1-1 to ask questions about the warning. -
A Concept of the Vortex Lift of Sharp-Edge Delta Wings Based on a Leading-Edge-Suction Analogy Tech Library Kafb, Nm
I A CONCEPT OF THE VORTEX LIFT OF SHARP-EDGE DELTA WINGS BASED ON A LEADING-EDGE-SUCTION ANALOGY TECH LIBRARY KAFB, NM OL3042b NASA TN D-3767 A CONCEPT OF THE VORTEX LIFT OF SHARP-EDGE DELTA WINGS BASED ON A LEADING-EDGE-SUCTION ANALOGY By Edward C. Polhamus Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - Price $1.00 A CONCEPT OF THE VORTEX LIFT OF SHARP-EDGE DELTA WINGS BASED ON A LEADING-EDGE-SUCTION ANALOGY By Edward C. Polhamus Langley Research Center SUMMARY A concept for the calculation of the vortex lift of sharp-edge delta wings is pre sented and compared with experimental data. The concept is based on an analogy between the vortex lift and the leading-edge suction associated with the potential flow about the leading edge. This concept, when combined with potential-flow theory modified to include the nonlinearities associated with the exact boundary condition and the loss of the lift component of the leading-edge suction, provides excellent prediction of the total lift for a wide range of delta wings up to angles of attack of 20° or greater. INTRODUCTION The aerodynamic characteristics of thin sharp-edge delta wings are of interest for supersonic aircraft and have been the subject of theoretical and experimental studies for many years in both the subsonic and supersonic speed ranges. Of particular interest at subsonic speeds has been the formation and influence of the leading-edge separation vor tex that occurs on wings having sharp, highly swept leading edges. -
Three Types of Horizontal Vortices Observed in Wildland Mass And
1624 JOURNAL OF CLIMATE AND APPLIED METEOROLOGY VOLUME26 Three Types of Horizontal Vortices Observed in Wildland Mas~ and Crown Fires DoNALD A. HAINES U.S. Department ofAgriculture, Forest Service, North Central Forest Experiment Station, East Lansing, Ml 48823 MAHLON C. SMITH Department ofMechanical Engineering, Michigan State University, East Lansing, Ml 48824 (Manuscript received 25 October 1986, in final form 4 May 1987) ABSTRACT Observation shows that three types of horizontal vortices may form during intense wildland fires. Two of these vortices are longitudinal relative to the ambient wind and the third is transverse. One of the longitudinal types, a vortex pair, occurs with extreme heat and low to moderate wind speeds. It may be a somewhat common structure on the flanks of intense crown fires when burning is concentrated along the fire's perimeter. The second longitudinal type, a single vortex, occurs with high winds and can dominate the entire fire. The third type, the transverse vortex, occurs on the upstream side of the convection column during intense burning and relatively low winds. These vortices are important because they contribute to fire spread and are a threat to fire fighter safety. This paper documents field observations of the vortices and supplies supportive meteorological and fuel data. The discussion includes applicable laboratory and conceptual studies in fluid flow and heat transfer that may apply to vortex formation. 1. Introduction experiments showed that when air flowed parallel to a heated metal ribbon that simulated the flank of a crown The occurrence of vertical vortices in wildland fires fire, a thin, buoyant plume capped with a vortex pair has been well documented as well as mathematically developed above the ribbon along its length. -
Squall Lines: Meteorology, Skywarn Spotting, & a Brief Look at the 18
Squall Lines: Meteorology, Skywarn Spotting, & A Brief Look At The 18 June 2010 Derecho Gino Izzi National Weather Service, Chicago IL Outline • Meteorology 301: Squall lines – Brief review of thunderstorm basics – Squall lines – Squall line tornadoes – Mesovorticies • Storm spotting for squall lines • Brief Case Study of 18 June 2010 Event Thunderstorm Ingredients • Moisture – Gulf of Mexico most common source locally Thunderstorm Ingredients • Lifting Mechanism(s) – Fronts – Jet Streams – “other” boundaries – topography Thunderstorm Ingredients • Instability – Measure of potential for air to accelerate upward – CAPE: common variable used to quantify magnitude of instability < 1000: weak 1000-2000: moderate 2000-4000: strong 4000+: extreme Thunderstorms Thunderstorms • Moisture + Instability + Lift = Thunderstorms • What kind of thunderstorms? – Single Cell – Multicell/Squall Line – Supercells Thunderstorm Types • What determines T-storm Type? – Short/simplistic answer: CAPE vs Shear Thunderstorm Types • What determines T-storm Type? (Longer/more complex answer) – Lot we don’t know, other factors (besides CAPE/shear) include • Strength of forcing • Strength of CAP • Shear WRT to boundary • Other stuff Thunderstorm Types • Multi-cell squall lines most common type of severe thunderstorm type locally • Most common type of severe weather is damaging winds • Hail and brief tornadoes can occur with most the intense squall lines Squall Lines & Spotting Squall Line Terminology • Squall Line : a relatively narrow line of thunderstorms, often -
J5J.1 1. Introduction the Bow Echo and Mesoscale Convective Vortex
J5J.1 Keynote Talk: BAMEX Observations of Mesoscale Convective Vortices Christopher A. Davis and Stanley B. Trier National Center for Atmospheric Research Boulder, Colorado 80307 1. Introduction and a Lear jet leased from Weather Modification Inc. (WMI). Mobile Ground- The Bow Echo and Mesoscale based facilities included the Mobile Convective Vortex (MCV) Experiment Integrated Profiling System (MIPS) from (BAMEX) is a study of life cycles of the University of Alabama (Huntsville) mesoscale convective systems using three and three Mobile GPS-Loran Atmospheric aircraft and multiple, mobile ground-based Sounding Systems (MGLASS) from instruments. It represents a combination of NCAR. The MIPS and MGLASS were two related programs to investigate (a) referred to as the ground based observing bow echoes (Fujita, 1978), principally system (GBOS). The two P-3s were each those which produce damaging surface equipped with tail Doppler radars, the winds and last at least 4 hours and (b) Electra Doppler Radar (ELDORA) being larger convective systems which produce on the NRL P-3. The WMI Lear jet long lived mesoscale convective vortices deployed dropsondes from roughly 12 km (MCVs) (Bartels and Maddox, 1991). The AGL. project was conducted from 20 May to 6 For MCSs, the objective was to sample July, 2003, based at MidAmerica Airport mesoscale wind and temperature fields in Mascoutah, Illinois. A detailed while obtaining high-resolution snapshots overview of the project, including of convection structures, especially those preliminary results appears in Davis et al. (2004). The reader wishing to view processed BAMEX data should visit http://www.joss.ucar.edu/bamex/catalog/. In this keynote address, I will focus on the study of MCVs, based particularly observations from airborne Doppler radar and dropsondes and wind profilers. -
NWS Unified Surface Analysis Manual
Unified Surface Analysis Manual Weather Prediction Center Ocean Prediction Center National Hurricane Center Honolulu Forecast Office November 21, 2013 Table of Contents Chapter 1: Surface Analysis – Its History at the Analysis Centers…………….3 Chapter 2: Datasets available for creation of the Unified Analysis………...…..5 Chapter 3: The Unified Surface Analysis and related features.……….……….19 Chapter 4: Creation/Merging of the Unified Surface Analysis………….……..24 Chapter 5: Bibliography………………………………………………….…….30 Appendix A: Unified Graphics Legend showing Ocean Center symbols.….…33 2 Chapter 1: Surface Analysis – Its History at the Analysis Centers 1. INTRODUCTION Since 1942, surface analyses produced by several different offices within the U.S. Weather Bureau (USWB) and the National Oceanic and Atmospheric Administration’s (NOAA’s) National Weather Service (NWS) were generally based on the Norwegian Cyclone Model (Bjerknes 1919) over land, and in recent decades, the Shapiro-Keyser Model over the mid-latitudes of the ocean. The graphic below shows a typical evolution according to both models of cyclone development. Conceptual models of cyclone evolution showing lower-tropospheric (e.g., 850-hPa) geopotential height and fronts (top), and lower-tropospheric potential temperature (bottom). (a) Norwegian cyclone model: (I) incipient frontal cyclone, (II) and (III) narrowing warm sector, (IV) occlusion; (b) Shapiro–Keyser cyclone model: (I) incipient frontal cyclone, (II) frontal fracture, (III) frontal T-bone and bent-back front, (IV) frontal T-bone and warm seclusion. Panel (b) is adapted from Shapiro and Keyser (1990) , their FIG. 10.27 ) to enhance the zonal elongation of the cyclone and fronts and to reflect the continued existence of the frontal T-bone in stage IV. -
Downloaded 09/30/21 06:43 PM UTC JUNE 1996 MONTEVERDI and JOHNSON 247
246 WEATHER AND FORECASTING VOLUME 11 A Supercell Thunderstorm with Hook Echo in the San Joaquin Valley, California JOHN P. MONTEVERDI Department of Geosciences, San Francisco State University, San Francisco, California STEVE JOHNSON Association of Central California Weather Observers, Fresno, California (Manuscript received 30 January 1995, in ®nal form 9 February 1996) ABSTRACT This study documents a damaging supercell thunderstorm that occurred in California's San Joaquin Valley on 5 March 1994. The storm formed in a ``cold sector'' environment similar to that documented for several other recent Sacramento Valley severe thunderstorm events. Analyses of hourly subsynoptic surface and radar data suggested that two thunderstorms with divergent paths developed from an initial echo that had formed just east of the San Francisco Bay region. The southern storm became severe as it ingested warmer, moister boundary layer air in the south-central San Joaquin Valley. A well-developed hook echo with a 63-dBZ core was observed by a privately owned 5-cm radar as the storm passed through the Fresno area. Buoyancy parameters and ho- dograph characteristics were obtained both for estimated conditions for Fresno [on the basis of a modi®ed morning Oakland (OAK) sounding] and for the actual storm environment (on the basis of a radiosonde launched from Lemoore Naval Air Station at about the time of the storm's passage through the Fresno area). Both the estimated and actual hodographs essentially were straight and suggested storm splitting. Although the actual CAPE was similar to that which was estimated, the observed magnitude of the low-level shear was considerably greater than the estimate. -
Mesoscale Convective Vortex That Causes Tornado-Like Vortices Over the Sea: a Potential Risk to Maritime Traffic
JUNE 2019 T O C H I M O T O E T A L . 1989 Mesoscale Convective Vortex that Causes Tornado-Like Vortices over the Sea: A Potential Risk to Maritime Traffic EIGO TOCHIMOTO Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan SHO YOKOTA Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan HIROSHI NIINO Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan WATARU YANASE Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan (Manuscript received 24 August 2018, in final form 28 January 2019) ABSTRACT Strong gusty winds in a weak maritime extratropical cyclone (EC) over the Tsushima Strait in the south- western Sea of Japan capsized several fishing boats on 1 September 2015. A C-band Doppler radar recorded a spiral-shaped reflectivity pattern associated with a convective system and a Doppler velocity pattern of a vortex with a diameter of 30 km [meso-b-scale vortex (MBV)] near the location of the wreck. A high- resolution numerical simulation with horizontal grid interval of 50 m successfully reproduced the spiral- shaped precipitation pattern associated with the MBV and tornado-like strong vortices that had a maximum 2 wind speed exceeding 50 m s 1 and repeatedly developed in the MBV. The simulated MBV had a strong cyclonic circulation comparable to a mesocyclone in a supercell storm. Unlike mesocyclones associated with a supercell storm, however, its vorticity was largest near the surface and decreased monotonically with in- creasing height. The strong vorticity of the MBV near the surface originated from a horizontal shear line in the EC.