What Controls Tropical Cyclone Size and Intensity?
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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). -
Lecture 15 Hurricane Structure
MET 200 Lecture 15 Hurricanes Last Lecture: Atmospheric Optics Structure and Climatology The amazing variety of optical phenomena observed in the atmosphere can be explained by four physical mechanisms. • What is the structure or anatomy of a hurricane? • How to build a hurricane? - hurricane energy • Hurricane climatology - when and where Hurricane Katrina • Scattering • Reflection • Refraction • Diffraction 1 2 Colorado Flood Damage Hurricanes: Useful Websites http://www.wunderground.com/hurricane/ http://www.nrlmry.navy.mil/tc_pages/tc_home.html http://tropic.ssec.wisc.edu http://www.nhc.noaa.gov Hurricane Alberto Hurricanes are much broader than they are tall. 3 4 Hurricane Raymond Hurricane Raymond 5 6 Hurricane Raymond Hurricane Raymond 7 8 Hurricane Raymond: wind shear Typhoon Francisco 9 10 Typhoon Francisco Typhoon Francisco 11 12 Typhoon Francisco Typhoon Francisco 13 14 Typhoon Lekima Typhoon Lekima 15 16 Typhoon Lekima Hurricane Priscilla 17 18 Hurricane Priscilla Hurricanes are Tropical Cyclones Hurricanes are a member of a family of cyclones called Tropical Cyclones. West of the dateline these storms are called Typhoons. In India and Australia they are called simply Cyclones. 19 20 Hurricane Isaac: August 2012 Characteristics of Tropical Cyclones • Low pressure systems that don’t have fronts • Cyclonic winds (counter clockwise in Northern Hemisphere) • Anticyclonic outflow (clockwise in NH) at upper levels • Warm at their center or core • Wind speeds decrease with height • Symmetric structure about clear "eye" • Latent heat from condensation in clouds primary energy source • Form over warm tropical and subtropical oceans NASA VIIRS Day-Night Band 21 22 • Differences between hurricanes and midlatitude storms: Differences between hurricanes and midlatitude storms: – energy source (latent heat vs temperature gradients) - Winter storms have cold and warm fronts (asymmetric). -
Investigation and Prediction of Hurricane Eyewall
INVESTIGATION AND PREDICTION OF HURRICANE EYEWALL REPLACEMENT CYCLES By Matthew Sitkowski A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Atmospheric and Oceanic Sciences) at the UNIVERSITY OF WISCONSIN-MADISON 2012 Date of final oral examination: 4/9/12 The dissertation is approved by the following members of the Final Oral Committee: James P. Kossin, Affiliate Professor, Atmospheric and Oceanic Sciences Daniel J. Vimont, Professor, Atmospheric and Oceanic Sciences Steven A. Ackerman, Professor, Atmospheric and Oceanic Sciences Jonathan E. Martin, Professor, Atmospheric and Oceanic Sciences Gregory J. Tripoli, Professor, Atmospheric and Oceanic Sciences i Abstract Flight-level aircraft data and microwave imagery are analyzed to investigate hurricane secondary eyewall formation and eyewall replacement cycles (ERCs). This work is motivated to provide forecasters with new guidance for predicting and better understanding the impacts of ERCs. A Bayesian probabilistic model that determines the likelihood of secondary eyewall formation and a subsequent ERC is developed. The model is based on environmental and geostationary satellite features. A climatology of secondary eyewall formation is developed; a 13% chance of secondary eyewall formation exists when a hurricane is located over water, and is also utilized by the model. The model has been installed at the National Hurricane Center and has skill in forecasting secondary eyewall formation out to 48 h. Aircraft reconnaissance data from 24 ERCs are examined to develop a climatology of flight-level structure and intensity changes associated with ERCs. Three phases are identified based on the behavior of the maximum intensity of the hurricane: intensification, weakening and reintensification. -
Observed Cyclone–Anticyclone Tropopause Vortex Asymmetries
JANUARY 2005 H A K I M A N D CANAVAN 231 Observed Cyclone–Anticyclone Tropopause Vortex Asymmetries GREGORY J. HAKIM AND AMELIA K. CANAVAN University of Washington, Seattle, Washington (Manuscript received 30 September 2003, in final form 28 June 2004) ABSTRACT Relatively little is known about coherent vortices near the extratropical tropopause, even with regard to basic facts about their frequency of occurrence, longevity, and structure. This study addresses these issues through an objective census of observed tropopause vortices. The authors test a hypothesis regarding vortex-merger asymmetry where cyclone pairs are repelled and anticyclone pairs are attracted by divergent flow due to frontogenesis. Emphasis is placed on arctic vortices, where jet stream influences are weaker, in order to facilitate comparisons with earlier idealized numerical simulations. Results show that arctic cyclones are more numerous, persistent, and stronger than arctic anticyclones. An average of 15 cyclonic vortices and 11 anticyclonic vortices are observed per month, with maximum frequency of occurrence for cyclones (anticyclones) during winter (summer). There are are about 47% more cyclones than anticyclones that survive at least 4 days, and for longer lifetimes, 1-day survival probabilities are nearly constant at 65% for cyclones, and 55% for anticyclones. Mean tropopause potential-temperature amplitude is 13 K for cyclones and 11 K for anticyclones, with cyclones exhibiting a greater tail toward larger values. An analysis of close-proximity vortex pairs reveals divergence between cyclones and convergence be- tween anticyclones. This result agrees qualitatively with previous idealized numerical simulations, although it is unclear to what extent the divergent circulations regulate vortex asymmetries. -
Extratropical Cyclones and Anticyclones
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION Courtesy of Jeff Schmaltz, the MODIS Rapid Response Team at NASA GSFC/NASA Extratropical Cyclones 10 and Anticyclones CHAPTER OUTLINE INTRODUCTION A TIME AND PLACE OF TRAGEDY A LiFE CYCLE OF GROWTH AND DEATH DAY 1: BIRTH OF AN EXTRATROPICAL CYCLONE ■■ Typical Extratropical Cyclone Paths DaY 2: WiTH THE FI TZ ■■ Portrait of the Cyclone as a Young Adult ■■ Cyclones and Fronts: On the Ground ■■ Cyclones and Fronts: In the Sky ■■ Back with the Fitz: A Fateful Course Correction ■■ Cyclones and Jet Streams 298 9781284027372_CH10_0298.indd 298 8/10/13 5:00 PM © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION Introduction 299 DaY 3: THE MaTURE CYCLONE ■■ Bittersweet Badge of Adulthood: The Occlusion Process ■■ Hurricane West Wind ■■ One of the Worst . ■■ “Nosedive” DaY 4 (AND BEYOND): DEATH ■■ The Cyclone ■■ The Fitzgerald ■■ The Sailors THE EXTRATROPICAL ANTICYCLONE HIGH PRESSURE, HiGH HEAT: THE DEADLY EUROPEAN HEAT WaVE OF 2003 PUTTING IT ALL TOGETHER ■■ Summary ■■ Key Terms ■■ Review Questions ■■ Observation Activities AFTER COMPLETING THIS CHAPTER, YOU SHOULD BE ABLE TO: • Describe the different life-cycle stages in the Norwegian model of the extratropical cyclone, identifying the stages when the cyclone possesses cold, warm, and occluded fronts and life-threatening conditions • Explain the relationship between a surface cyclone and winds at the jet-stream level and how the two interact to intensify the cyclone • Differentiate between extratropical cyclones and anticyclones in terms of their birthplaces, life cycles, relationships to air masses and jet-stream winds, threats to life and property, and their appearance on satellite images INTRODUCTION What do you see in the diagram to the right: a vase or two faces? This classic psychology experiment exploits our amazing ability to recognize visual patterns. -
ESSENTIALS of METEOROLOGY (7Th Ed.) GLOSSARY
ESSENTIALS OF METEOROLOGY (7th ed.) GLOSSARY Chapter 1 Aerosols Tiny suspended solid particles (dust, smoke, etc.) or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. Air density The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm3 or kg/m3. Also See Density. Air pressure The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of (atmospheric mercury (Hg) or in hectopascals (hPa). pressure) Atmosphere The envelope of gases that surround a planet and are held to it by the planet's gravitational attraction. The earth's atmosphere is mainly nitrogen and oxygen. Carbon dioxide (CO2) A colorless, odorless gas whose concentration is about 0.039 percent (390 ppm) in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in the earth's atmospheric greenhouse effect. Solid CO2 is called dry ice. Climate The accumulation of daily and seasonal weather events over a long period of time. Front The transition zone between two distinct air masses. Hurricane A tropical cyclone having winds in excess of 64 knots (74 mi/hr). Ionosphere An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist. Lapse rate The rate at which an atmospheric variable (usually temperature) decreases with height. (See Environmental lapse rate.) Mesosphere The atmospheric layer between the stratosphere and the thermosphere. -
Central Region Technical Attachment 95-08 Examination of an Apparent
CRH SSD APRIL 1995 CENTRAL REGION TECHNICAL ATTACHMENT 95-08 EXAMINATION OF AN APPARENT LANDSPOUT IN THE EASTERN BLACK HILLS OF WESTERN SOUTH DAKOTA David L. Hintz1 and Matthew J. Bunkers National Weather Service Office Rapid City, South Dakota 1. Abstract On June 29, 1994, an apparent landspout occurred in the Black Hills of South Dakota. This landspout exhibited most of the features characteristic of traditional landspouts documented in eastern Colorado. The landspout lasted 3 to 8 minutes, had a width of less than 20 m and a path of 1 to 3 km, produced estimated wind speeds of Fl intensity (33 to 50 m s1), and emanated from a towering cumulus (TCU) cloud located along a quasi-stationary convergencq/cyclonic shear zone. No radar echo was observed with this event; however, a supercell thunderstorm was located 80-100 km to the east. National Weather Service meteorologists surveyed the “very localized” damage area and ruled out the possibility of the landspout being related to microburst, gustnado, or dust devil activity, as winds away from the landspout were less than 3 m s1. The landspout apparently “detached” from the parent TCU and damaged a farm which resulted in $1,000 dollars in expenses. 2. Introduction During the late 1980’s and early 1990’s researchers documented a phe nomenon with subtle differences from traditional tornadoes and waterspouts, herein referred to as the landspout (Seargent 1994; Brady and Szoke 1988, 1989; Bluestein 1985). The term “landspout” was actually coined by Bluestein (I985)(in the formal literature) when he observed this type of vortex along an Oklahoma squall line. -
Synoptic Meteorology
Lecture Notes on Synoptic Meteorology For Integrated Meteorological Training Course By Dr. Prakash Khare Scientist E India Meteorological Department Meteorological Training Institute Pashan,Pune-8 186 IMTC SYLLABUS OF SYNOPTIC METEOROLOGY (FOR DIRECT RECRUITED S.A’S OF IMD) Theory (25 Periods) ❖ Scales of weather systems; Network of Observatories; Surface, upper air; special observations (satellite, radar, aircraft etc.); analysis of fields of meteorological elements on synoptic charts; Vertical time / cross sections and their analysis. ❖ Wind and pressure analysis: Isobars on level surface and contours on constant pressure surface. Isotherms, thickness field; examples of geostrophic, gradient and thermal winds: slope of pressure system, streamline and Isotachs analysis. ❖ Western disturbance and its structure and associated weather, Waves in mid-latitude westerlies. ❖ Thunderstorm and severe local storm, synoptic conditions favourable for thunderstorm, concepts of triggering mechanism, conditional instability; Norwesters, dust storm, hail storm. Squall, tornado, microburst/cloudburst, landslide. ❖ Indian summer monsoon; S.W. Monsoon onset: semi permanent systems, Active and break monsoon, Monsoon depressions: MTC; Offshore troughs/vortices. Influence of extra tropical troughs and typhoons in northwest Pacific; withdrawal of S.W. Monsoon, Northeast monsoon, ❖ Tropical Cyclone: Life cycle, vertical and horizontal structure of TC, Its movement and intensification. Weather associated with TC. Easterly wave and its structure and associated weather. ❖ Jet Streams – WMO definition of Jet stream, different jet streams around the globe, Jet streams and weather ❖ Meso-scale meteorology, sea and land breezes, mountain/valley winds, mountain wave. ❖ Short range weather forecasting (Elementary ideas only); persistence, climatology and steering methods, movement and development of synoptic scale systems; Analogue techniques- prediction of individual weather elements, visibility, surface and upper level winds, convective phenomena. -
Massachusetts Tropical Cyclone Profile August 2021
Commonwealth of Massachusetts Tropical Cyclone Profile August 2021 Commonwealth of Massachusetts Tropical Cyclone Profile Description Tropical cyclones, a general term for tropical storms and hurricanes, are low pressure systems that usually form over the tropics. These storms are referred to as “cyclones” due to their rotation. Tropical cyclones are among the most powerful and destructive meteorological systems on earth. Their destructive phenomena include storm surge, high winds, heavy rain, tornadoes, and rip currents. As tropical storms move inland, they can cause severe flooding, downed trees and power lines, and structural damage. Once a tropical cyclone no longer has tropical characteristics, it is then classified as a post-tropical system. The National Hurricane Center (NHC) has classified four stages of tropical cyclones: • Tropical Depression: A tropical cyclone with maximum sustained winds of 38 mph (33 knots) or less. • Tropical Storm: A tropical cyclone with maximum sustained winds of 39 to 73 mph (34 to 63 knots). • Hurricane: A tropical cyclone with maximum sustained winds of 74 mph (64 knots) or higher. • Major Hurricane: A tropical cyclone with maximum sustained winds of 111 mph (96 knots) or higher, corresponding to a Category 3, 4 or 5 on the Saffir-Simpson Hurricane Wind Scale. Primary Hazards Storm Surge and Storm Tide Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tide. Storm surge and large waves produced by hurricanes pose the greatest threat to life and property along the coast. They also pose a significant risk for drowning. Storm tide is the total water level rise during a storm due to the combination of storm surge and the astronomical tide. -
Airborne Radar Observations of Eye Configuration Changes, Bright
UDC 661.616.22:661.M)9.61: 661.601.81 Airborne Radar Observations of Eye Configuration Changes, Bright Band Distribution, and Precipitation Tilt During the 1969 Multiple Seeding Experiments in Hurricane Debbie' PETER G. BLACK-National Hurricane Research Laboratory, Environmental Research Laboratories, NOAA, Miami, Fla. HARRY V. SENN and CHARLES L. COURTRIGHT-Radar Meteorology Laboratory, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, Fla. ABSTRACT-Project Stormfury radar precipitation data radius of maximum winds follow closely the changes in gathered before, during, and after the multiple seedings of eyewall radius. It is suggested that the different results on the eyewall region of hurricane Debbie on Aug. 18 and 20, the 2 days might be attributable to seeding beyond the 1969, are used to study changes in the eye configuration, radius of maximum winds on the 18th and inside the the characteristics of the radar bright band, and the outer radius of maximum winds on the 20th. precipitation tilt. Increases in the echo-free area within The bright band is found in all quadrants of the storm the eye followed each of the five seedings on the 18th, within 100 n.mi. of the eye, sloping slightly upward near but followed only one seeding on the 20th. Changes in the eyewall. The inferred shears are directed outward and major axis orientation followed only one seeding on the slightly down band with height in both layers studied. 18th, but followed each seeding on the 20th. Similar The hurricane Debbie bright band and precipitation tilt studies conducted recently on unmodified storms suggest data compared favorably with those gathered in Betsy of that such changes do not occur naturally. -
Lecture 14. Extratropical Cyclones • in Mid-Latitudes, Much of Our Weather
Lecture 14. Extratropical Cyclones • In mid-latitudes, much of our weather is associated with a particular kind of storm, the extratropical cyclone Cyclone: circulation around low pressure center Some midwesterners call tornadoes cyclones Tropical cyclone = hurricane • Extratropical cyclones derive their energy from horizontal temperature con- trasts. • They typically form on a boundary between a warm and a cold air mass associated with an upper tropospheric jet stream • Their circulations affect the entire troposphere over a region 1000 km or more across. • Extratropical cyclones tend to develop with a particular lifecycle . • The low pressure center moves roughly with the speed of the 500 mb wind above it. • An extratropical cyclone tends to focus the temperature contrasts into ‘fron- tal zones’ of particularly rapid horizontal temperature change. The Norwegian Cyclone Model In 1922, well before routine upper air observations began, Bjerknes and Sol- berg in Bergen, Norway, codified experience from analyzing surface weather maps over Europe into the Norwegian Cyclone Model, a conceptual picture of the evolution of an ET cyclone and associated frontal zones at ground They noted that the strongest temperature gradients usually occur at the warm edge of the frontal zone, which they called the front. They classified fronts into four types, each with its own symbol: Cold front - Cold air advancing into warm air Warm front - Warm air advancing into cold air Stationary front - Neither airmass advances Occluded front - Looks like a cold front -
Characteristics of Supercells in the Rainband of Numerically Simulated Cyclone Sidr
SOLA, 2010, Vol. 6A, 025−028, doi:10.2151/sola.6A-007 25 Characteristics of Supercells in the Rainband of Numerically Simulated Cyclone Sidr Nasreen Akter1 and Kazuhisa Tsuboki1, 2 1Hydrospheric Atmospheric Research Center, Nagoya University, Nagoya, Japan 2Frontier Research Center for Global Change, JAMSTEC, Yokohama, Japan (Figs. 1b and 1c). The cell indicated in Fig. 1b is ~116 km away Abstract from the radar, and its local altitude is ~1 km. Also, no sounding data are available. The observed data are not sufficient for inves- Cyclone Sidr had an intense rainband east of the cyclone tigation of the detailed structure and intensity of the convective center. The rainband exhibited two strong convective lines (band cells along the band. axes) composed of convective cells. To study the characteristics of Therefore, the present study aims to clarify the characteristics the convective cells, a simulation was performed at 1-km resolu- of the convective cells in the rainband of Cyclone Sidr over the tion by using a cloud-resolving model. In both band axes, some sea and the environmental factors affecting cell development. For cells showed the characteristic structure of a supercell. Supercells this purpose, a high-resolution simulation was performed using within the outer axis had stronger updraft, more intense precipita- the Cloud-Resolving Storm Simulator (CReSS) model (Tsuboki tion, and a longer lifetime than those of the inner axis. The values and Sakakibara 2007). of the CAPE and helicity are different in the strong vertical shear environment of the inner and outer axes. A large moisture flux was present throughout the troposphere on the east side of the outer 2.