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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). -
Rain Shadows
WEB TUTORIAL 24.2 Rain Shadows Text Sections Section 24.4 Earth's Physical Environment, p. 428 Introduction Atmospheric circulation patterns strongly influence the Earth's climate. Although there are distinct global patterns, local variations can be explained by factors such as the presence of absence of mountain ranges. In this tutorial we will examine the effects on climate of a mountain range like the Andes of South America. Learning Objectives • Understand the effects that topography can have on climate. • Know what a rain shadow is. Narration Rain Shadows Why might the communities at a certain latitude in South America differ from those at a similar latitude in Africa? For example, how does the distribution of deserts on the western side of South America differ from the distribution seen in Africa? What might account for this difference? Unlike the deserts of Africa, the Atacama Desert in Chile is a result of topography. The Andes mountain chain extends the length of South America and has a pro- nounced influence on climate, disrupting the tidy latitudinal patterns that we see in Africa. Let's look at the effects on climate of a mountain range like the Andes. The prevailing winds—which, in the Andes, come from the southeast—reach the foot of the mountains carrying warm, moist air. As the air mass moves up the wind- ward side of the range, it expands because of the reduced pressure of the column of air above it. The rising air mass cools and can no longer hold as much water vapor. The water vapor condenses into clouds and results in precipitation in the form of rain and snow, which fall on the windward slope. -
Surface Cyclolysis in the North Pacific Ocean. Part I
748 MONTHLY WEATHER REVIEW VOLUME 129 Surface Cyclolysis in the North Paci®c Ocean. Part I: A Synoptic Climatology JONATHAN E. MARTIN,RHETT D. GRAUMAN, AND NATHAN MARSILI Department of Atmospheric and Oceanic Sciences, University of WisconsinÐMadison, Madison, Wisconsin (Manuscript received 20 January 2000, in ®nal form 16 August 2000) ABSTRACT A continuous 11-yr sample of extratropical cyclones in the North Paci®c Ocean is used to construct a synoptic climatology of surface cyclolysis in the region. The analysis concentrates on the small population of all decaying cyclones that experience at least one 12-h period in which the sea level pressure increases by 9 hPa or more. Such periods are de®ned as threshold ®lling periods (TFPs). A subset of TFPs, referred to as rapid cyclolysis periods (RCPs), characterized by sea level pressure increases of at least 12 hPa in 12 h, is also considered. The geographical distribution, spectrum of decay rates, and the interannual variability in the number of TFP and RCP cyclones are presented. The Gulf of Alaska and Paci®c Northwest are found to be primary regions for moderate to rapid cyclolysis with a secondary frequency maximum in the Bering Sea. Moderate to rapid cyclolysis is found to be predominantly a cold season phenomena most likely to occur in a cyclone with an initially low sea level pressure minimum. The number of TFP±RCP cyclones in the North Paci®c basin in a given year is fairly well correlated with the phase of the El NinÄo±Southern Oscillation (ENSO) as measured by the multivariate ENSO index. -
Hurricane Paths: Comparing Places with Different Prevailing Winds
Name ___________________________ Hurricane Paths: Comparing Places with Different Prevailing Winds To understand where hurricanes usually start and what direction they usually move, it helps to have a clear mental image of the pattern of prevailing winds in the world. One way to get this image is to make a careful comparison of wind observations in several places. The diagrams on the right are examples of a special kind of graph called a wind rose. The number in the center indicates the percentage of time the air is calm (no wind). Each of the eight lines radiating away from the center shows the percentage of time the wind blows FROM that direction. Repeat: The lines point to the direction the wind is blowing FROM. Please answer the following questions. 1) According to the map above, Boston has calm air about 12% of the time; the percentage of time San Juan, Puerto Rico, has calm air is _____ . 2) In San Juan, the wind blows the largest percentage of time from the northeast; in Boston, the wind blows from the _________ more often than from any other direction. 3) Use the wind rose graphs on pages 2 and 3. To get an idea about the net zonal flow of air in each location, add up the total percentage of time the wind blows from the southwest, west, and northwest, and subtract the total percentage from the southeast, east, and northeast total percentage. The result is the net westerly component - it is a positive number if the flow is mainly westerly (from the west), and a negative number if the flow is easterly (from the east). -
Adam J Zebzda
INFLUENCES OF THE URBAN HEAT ISLAND EFFECT AND BROWN OCEAN EFFECT AND THEIR IMPACTS ON LANDFALLING TROPICAL CYCLONES AN PROVINCIAL ATMOSPHERIC CONDITIONS Adam Jozef Zebzda*1 Mount Tabor High School INTRODUCTION (TS) individually. The criteria for selecting a TS for the study was fairly simple. The necessary aspects of each Through the decades, tropical cyclones have shaped system were that it over went intensification overland our coastal infrastructure and continue to do so. During (characterized by an increase in wind speed and a the 2017 Hurricane Season alone, Hurricanes Harvey, decrease of central pressure), that the location of the TS Irma, and Maria have shown us our flaws in urban was within 75 miles (121 kilometers) of a major development and planning, costing billions of dollars in metropolitan area (characterized by containing a damages and loss of life. Tropical Meteorology has population more than 500 thousand residents), and was shown that these cyclones intensify over warm, tropical, substantially far enough from an ocean so as not to be oceanic waters with low vertical wind shear and a moist directly influenced in intensification. With the use of atmosphere; however, could a large metropolitan area satellite, it was possible to determine the area and do the same? Records exist of overland cyclone magnitude of an urban heat island remotely and intensification, such as Tropical Storm Erin (2007). This accurately. particular system intensified over the state of Oklahoma, only 65 miles (105 kilometers) northwest of Oklahoma Once TS case studies were developed, the exact City, reaching winds of 80 miles per hour (mph). -
Climatology, Variability, and Return Periods of Tropical Cyclone Strikes in the Northeastern and Central Pacific Ab Sins Nicholas S
Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School March 2019 Climatology, Variability, and Return Periods of Tropical Cyclone Strikes in the Northeastern and Central Pacific aB sins Nicholas S. Grondin Louisiana State University, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Climate Commons, Meteorology Commons, and the Physical and Environmental Geography Commons Recommended Citation Grondin, Nicholas S., "Climatology, Variability, and Return Periods of Tropical Cyclone Strikes in the Northeastern and Central Pacific asinB s" (2019). LSU Master's Theses. 4864. https://digitalcommons.lsu.edu/gradschool_theses/4864 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. CLIMATOLOGY, VARIABILITY, AND RETURN PERIODS OF TROPICAL CYCLONE STRIKES IN THE NORTHEASTERN AND CENTRAL PACIFIC BASINS A Thesis Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Master of Science in The Department of Geography and Anthropology by Nicholas S. Grondin B.S. Meteorology, University of South Alabama, 2016 May 2019 Dedication This thesis is dedicated to my family, especially mom, Mim and Pop, for their love and encouragement every step of the way. This thesis is dedicated to my friends and fraternity brothers, especially Dillon, Sarah, Clay, and Courtney, for their friendship and support. This thesis is dedicated to all of my teachers and college professors, especially Mrs. -
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. -
Balanced Flow Natural Coordinates
Balanced Flow • The pressure and velocity distributions in atmospheric systems are related by relatively simple, approximate force balances. • We can gain a qualitative understanding by considering steady-state conditions, in which the fluid flow does not vary with time, and by assuming there are no vertical motions. • To explore these balanced flow conditions, it is useful to define a new coordinate system, known as natural coordinates. Natural Coordinates • Natural coordinates are defined by a set of mutually orthogonal unit vectors whose orientation depends on the direction of the flow. Unit vector tˆ points along the direction of the flow. ˆ k kˆ Unit vector nˆ is perpendicular to ˆ t the flow, with positive to the left. kˆ nˆ ˆ t nˆ Unit vector k ˆ points upward. ˆ ˆ t nˆ tˆ k nˆ ˆ r k kˆ Horizontal velocity: V = Vtˆ tˆ kˆ nˆ ˆ V is the horizontal speed, t nˆ ˆ which is a nonnegative tˆ tˆ k nˆ scalar defined by V ≡ ds dt , nˆ where s ( x , y , t ) is the curve followed by a fluid parcel moving in the horizontal plane. To determine acceleration following the fluid motion, r dV d = ()Vˆt dt dt r dV dV dˆt = ˆt +V dt dt dt δt δs δtˆ δψ = = = δtˆ t+δt R tˆ δψ δψ R radius of curvature (positive in = R δs positive n direction) t n R > 0 if air parcels turn toward left R < 0 if air parcels turn toward right ˆ dtˆ nˆ k kˆ = (taking limit as δs → 0) tˆ R < 0 ds R kˆ nˆ ˆ ˆ ˆ t nˆ dt dt ds nˆ ˆ ˆ = = V t nˆ tˆ k dt ds dt R R > 0 nˆ r dV dV dˆt = ˆt +V dt dt dt r 2 dV dV V vector form of acceleration following = ˆt + nˆ dt dt R fluid motion in natural coordinates r − fkˆ ×V = − fVnˆ Coriolis (always acts normal to flow) ⎛ˆ ∂Φ ∂Φ ⎞ − ∇ pΦ = −⎜t + nˆ ⎟ pressure gradient ⎝ ∂s ∂n ⎠ dV ∂Φ = − dt ∂s component equations of horizontal V 2 ∂Φ momentum equation (isobaric) in + fV = − natural coordinate system R ∂n dV ∂Φ = − Balance of forces parallel to flow. -
Ex-Hurricane Ophelia 16 October 2017
Ex-Hurricane Ophelia 16 October 2017 On 16 October 2017 ex-hurricane Ophelia brought very strong winds to western parts of the UK and Ireland. This date fell on the exact 30th anniversary of the Great Storm of 16 October 1987. Ex-hurricane Ophelia (named by the US National Hurricane Center) was the second storm of the 2017-2018 winter season, following Storm Aileen on 12 to 13 September. The strongest winds were around Irish Sea coasts, particularly west Wales, with gusts of 60 to 70 Kt or higher in exposed coastal locations. Impacts The most severe impacts were across the Republic of Ireland, where three people died from falling trees (still mostly in full leaf at this time of year). There was also significant disruption across western parts of the UK, with power cuts affecting thousands of homes and businesses in Wales and Northern Ireland, and damage reported to a stadium roof in Barrow, Cumbria. Flights from Manchester and Edinburgh to the Republic of Ireland and Northern Ireland were cancelled, and in Wales some roads and railway lines were closed. Ferry services between Wales and Ireland were also disrupted. Storm Ophelia brought heavy rain and very mild temperatures caused by a southerly airflow drawing air from the Iberian Peninsula. Weather data Ex-hurricane Ophelia moved on a northerly track to the west of Spain and then north along the west coast of Ireland, before sweeping north-eastwards across Scotland. The sequence of analysis charts from 12 UTC 15 to 12 UTC 17 October shows Ophelia approaching and tracking across Ireland and Scotland. -
Meteorology – Lecture 19
Meteorology – Lecture 19 Robert Fovell [email protected] 1 Important notes • These slides show some figures and videos prepared by Robert G. Fovell (RGF) for his “Meteorology” course, published by The Great Courses (TGC). Unless otherwise identified, they were created by RGF. • In some cases, the figures employed in the course video are different from what I present here, but these were the figures I provided to TGC at the time the course was taped. • These figures are intended to supplement the videos, in order to facilitate understanding of the concepts discussed in the course. These slide shows cannot, and are not intended to, replace the course itself and are not expected to be understandable in isolation. • Accordingly, these presentations do not represent a summary of each lecture, and neither do they contain each lecture’s full content. 2 Animations linked in the PowerPoint version of these slides may also be found here: http://people.atmos.ucla.edu/fovell/meteo/ 3 Mesoscale convective systems (MCSs) and drylines 4 This map shows a dryline that formed in Texas during April 2000. The dryline is indicated by unfilled half-circles in orange, pointing at the more moist air. We see little T contrast but very large TD change. Dew points drop from 68F to 29F -- huge decrease in humidity 5 Animation 6 Supercell thunderstorms 7 The secret ingredient for supercells is large amounts of vertical wind shear. CAPE is necessary but sufficient shear is essential. It is shear that makes the difference between an ordinary multicellular thunderstorm and the rotating supercell. The shear implies rotation. -
Piecewise Potential Vorticity Diagnosis of a Rapid Cyclolysis Event
1264 MONTHLY WEATHER REVIEW VOLUME 130 Surface Cyclolysis in the North Paci®c Ocean. Part II: Piecewise Potential Vorticity Diagnosis of a Rapid Cyclolysis Event JONATHAN E. MARTIN AND NATHAN MARSILI Department of Atmospheric and Oceanic Sciences, University of WisconsinÐMadison, Madison, Wisconsin (Manuscript received 19 March 2001, in ®nal form 26 October 2001) ABSTRACT Employing output from a successful numerical simulation, piecewise potential vorticity inversion is used to diagnose a rapid surface cyclolysis event that occurred south of the Aleutian Islands in late October 1996. The sea level pressure minimum of the decaying cyclone rose 35 hPa in 36 h as its associated upper-tropospheric wave quickly acquired a positive tilt while undergoing a rapid transformation from a nearly circular to a linear morphology. The inversion results demonstrate that the upper-tropospheric potential vorticity (PV) anomaly exerted the greatest control over the evolution of the lower-tropospheric height ®eld associated with the cyclone. A portion of the signi®cant height rises that characterized this event was directly associated with a diminution of the upper-tropospheric PV anomaly that resulted from negative PV advection by the full wind. This forcing has a clear parallel in more traditional synoptic/dynamic perspectives on lower-tropospheric development, which emphasize differential vorticity advection. Additional height rises resulted from promotion of increased anisotropy in the upper-tropospheric PV anomaly by upper-tropospheric deformation in the vicinity of a southwesterly jet streak. As the PV anomaly was thinned and elongated by the deformation, its associated geopotential height perturbation decreased throughout the troposphere in what is termed here PV attenuation. -
P1.6 Short-Term, Seasonal and Interannual Variability of the Vertical Distribution of Water Vapor Observed by Airs E
P1.6 SHORT-TERM, SEASONAL AND INTERANNUAL VARIABILITY OF THE VERTICAL DISTRIBUTION OF WATER VAPOR OBSERVED BY AIRS E. T. Olsen*, S. L. Granger, E. J. Fetzer Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 1. INTRODUCTION 3. EXAMPLES OF AIRS WATER VAPOR The Atmospheric Infrared Sounder (AIRS) consists 3.1 LEVEL 3 GLOBAL WATER VAPOR VERTICAL of a suite of instruments (Aumann et al. 2003) on board DISTRIBUTION the Aqua spacecraft which retrieve atmospheric parameters over the globe at radiosonde quality on a The following three images were derived from the daily basis in non-precipitating conditions with less than AIRS height resolved water vapor Level 3 product. 80% cloud cover. Much of the horizontal variability in Figures 1-3 is Although quantitative global measurements of associated with monsoon systems and Intertropical, water vapor have been available since the 1980's South Pacific and South Atlantic Convergences Zones. (Grody et al. 1980), the vertical resolution of these The distribution of water vapor is highly variable in measurements was very coarse. AIRS provides global the vertical dimension with concentrations varying more coverage amounting to 324,000 precipitable water vapor than four orders of magnitude with height. (Seidel 2002). profiles with spatial resolution at nadir of 45 km. The The progression of Figure1-3 shows the dramatic vertical resolution of AIRS tropospheric is 2 km for the reduction of water vapor with height as measured by the subset of these soundings which result from combined AIRS instrument. microwave and infrared soundings throughout the entire Figure 1 presents the global distribution of total vertical extent of the atmosphere.