Forecasting Mesoscale Convective Complex Movement in Central South America
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Soaring Weather
Chapter 16 SOARING WEATHER While horse racing may be the "Sport of Kings," of the craft depends on the weather and the skill soaring may be considered the "King of Sports." of the pilot. Forward thrust comes from gliding Soaring bears the relationship to flying that sailing downward relative to the air the same as thrust bears to power boating. Soaring has made notable is developed in a power-off glide by a conven contributions to meteorology. For example, soar tional aircraft. Therefore, to gain or maintain ing pilots have probed thunderstorms and moun altitude, the soaring pilot must rely on upward tain waves with findings that have made flying motion of the air. safer for all pilots. However, soaring is primarily To a sailplane pilot, "lift" means the rate of recreational. climb he can achieve in an up-current, while "sink" A sailplane must have auxiliary power to be denotes his rate of descent in a downdraft or in come airborne such as a winch, a ground tow, or neutral air. "Zero sink" means that upward cur a tow by a powered aircraft. Once the sailcraft is rents are just strong enough to enable him to hold airborne and the tow cable released, performance altitude but not to climb. Sailplanes are highly 171 r efficient machines; a sink rate of a mere 2 feet per second. There is no point in trying to soar until second provides an airspeed of about 40 knots, and weather conditions favor vertical speeds greater a sink rate of 6 feet per second gives an airspeed than the minimum sink rate of the aircraft. -
CALIFORNIA STATE UNIVERSITY, NORTHRIDGE FORECASTING CALIFORNIA THUNDERSTORMS a Thesis Submitted in Partial Fulfillment of the Re
CALIFORNIA STATE UNIVERSITY, NORTHRIDGE FORECASTING CALIFORNIA THUNDERSTORMS A thesis submitted in partial fulfillment of the requirements For the degree of Master of Arts in Geography By Ilya Neyman May 2013 The thesis of Ilya Neyman is approved: _______________________ _________________ Dr. Steve LaDochy Date _______________________ _________________ Dr. Ron Davidson Date _______________________ _________________ Dr. James Hayes, Chair Date California State University, Northridge ii TABLE OF CONTENTS SIGNATURE PAGE ii ABSTRACT iv INTRODUCTION 1 THESIS STATEMENT 12 IMPORTANT TERMS AND DEFINITIONS 13 LITERATURE REVIEW 17 APPROACH AND METHODOLOGY 24 TRADITIONALLY RECOGNIZED TORNADIC PARAMETERS 28 CASE STUDY 1: SEPTEMBER 10, 2011 33 CASE STUDY 2: JULY 29, 2003 48 CASE STUDY 3: JANUARY 19, 2010 62 CASE STUDY 4: MAY 22, 2008 91 CONCLUSIONS 111 REFERENCES 116 iii ABSTRACT FORECASTING CALIFORNIA THUNDERSTORMS By Ilya Neyman Master of Arts in Geography Thunderstorms are a significant forecasting concern for southern California. Even though convection across this region is less frequent than in many other parts of the country significant thunderstorm events and occasional severe weather does occur. It has been found that a further challenge in convective forecasting across southern California is due to the variety of sub-regions that exist including coastal plains, inland valleys, mountains and deserts, each of which is associated with different weather conditions and sometimes drastically different convective parameters. In this paper four recent thunderstorm case studies were conducted, with each one representative of a different category of seasonal and synoptic patterns that are known to affect southern California. In addition to supporting points made in prior literature there were numerous new and unique findings that were discovered during the scope of this research and these are discussed as they are investigated in their respective case study as applicable. -
The Iberian Peninsula Thermal Low
Q. J. R. Meteorol. Soc. (2003), 129, pp. 1491–1511 doi: 10.1256/qj.01.189 The Iberian Peninsula thermal low 1 2 By KLAUS P. HOINKA ¤ and MANUEL DE CASTRO 1Institut fur¨ Physik der Atmosph¨are, DLR, Oberpfaffenhofen, Germany 2Dpto. Ciencias Ambientales, Universidad Castilla-La Mancha, Toledo, Spain (Received 9 November 2001; revised 26 September 2002) SUMMARY Statistics of the thermal low above the Iberian Peninsula are presented for the period between 1979 and 1993, based on gridded data from the European Centre for Medium-Range Weather Forecasts reanalysis project. The sample of days with a thermal low above the Iberian Peninsula was selected objectively using criteria applied to mean-sea-level pressure and 925 hPa geopotential elds. The synoptic- and regional-scale horizontal structure is characterized by the climatology of the 500 hPa geopotential and mean-sea-level pressure distributions. The diurnal evolution of the mean-sea-level pressure is portrayed by mean elds at 00, 06, 12 and 18 UTC. The climatological vertical structure of the thermal low is shown by relation to meridional and zonal cross- sections passing through the thermal low’s centre. The diurnal evolution of the divergence, relative vorticity, potential temperature and vertical velocity is investigated. Statistics are presented also for the monthly frequency, geographical location, vertical extent and intensity of the Iberian thermal low. KEYWORDS: ERA data Heated low 1. INTRODUCTION A thermal low is a warm, shallow, non-frontal depression which forms above continental regions, mostly in the subtropics, but also in the lower midlatitudes. They form mostly during summer months because of the intense surface heating over land. -
Dynamical and Synoptic Characteristics of Heavy Rainfall Episodes in Southern Brazil
598 MONTHLY WEATHER REVIEW VOLUME 135 Dynamical and Synoptic Characteristics of Heavy Rainfall Episodes in Southern Brazil MATEUS DA SILVA TEIXEIRA Instituto Nacional de Pesquisas Espaciais, Sdo Jose dos Campos, Sdo Paulo, Brazil PRAKKI SATYAMURTY Centro de Previsao de Tempo e Estudos Climdticos/INPE,Sio Jose dos Campos, Sdo Paulo, Brazil (Manuscript received 21 December 2005, in final form 19 May 2006) ABSTRACT The dynamical and synoptic characteristics that distinguish heavy rainfall episodes from nonheavy rainfall episodes in southern Brazil are discussed. A heavy rainfall episode is defined here as one in which the 2 50 mm day-' isohyet encloses an area of not less than [0 000 km in the domain of southern Brazil. One hundred and seventy such events are identified in the 11-yr period'of 1991-2001. The mean flow patterns in the period of 1-3 days preceding the episodes show some striking synoptic-scale features that may be considered forerunners of these episodes: (i) a deepening midtropospheric trough in the eastern South Pacific approaches the continent 3 days before, (ii) a surface low,pressure center forms in northern Ar- gentina 1 day before, (iii) a northerly low-level jet develops over Paraguay 2 days before, and (iv) a strong moisture flux convergence over southern Brazil becomes prominent 1 day before the episode. A parameter called rainfall quantity, defined as the product .of the area enclosed by the 50 mm day-' isohyet and the average rainfall intensity, is,correlated with fields of atmospheric variables such as 500-hPa geopotential and 850-hPa meridional winds. Significant lag correlations show that the anomalies of some atmospheric vari- ables could be viewed as precursors of heavy rainfall in southern Brazil that can be explored for use in improving the forecasts. -
Extreme Climatic Characteristics Near the Coastline of the Southeast Region of Brazil in the Last 40 Years
Extreme Climatic Characteristics Near the Coastline of the Southeast Region of Brazil in the Last 40 Years Marilia Mitidieri Fernandes de Oliveira ( [email protected] ) Federal University of Rio de Janeiro: Universidade Federal do Rio de Janeiro Jorge Luiz Fernandes de Oliveira Fluminense Federal University Pedro José Farias Fernandes Fluminense Federal University, Physical Geography Laboratory (LAGEF), Eric Gilleland National, Center for Atmospheric Research (NCAR) Nelson Francisco Favilla Ebecken Federal University of Rio de Janeiro: Universidade Federal do Rio de Janeiro Research Article Keywords: ERA5 Reanalysis data, Non-parametric statistical tests, severe weather systems, subtropical cyclones Posted Date: June 7th, 2021 DOI: https://doi.org/10.21203/rs.3.rs-159473/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License 1 Extreme climatic characteristics near the coastline of the Southeast region of Brazil in the last 40 years Marilia Mitidieri Fernandes de Oliveira1, Jorge Luiz Fernandes de Oliveira2, Pedro José Farias Fernandes3, Eric Gilleland4, Nelson Francisco Favilla Ebecken1 1Federal University of Rio de Janeiro, Civil Engineering Postgraduate Program-COPPE/UFRJ, Center of Technology, Rio de Janeiro 21945-970, Brazil 2Fluminense Federal University, Geography Postgraduate Program, Department of Geography, Geoscience Institute, Niterói 24210-340, Brazil 3Fluminense Federal University, Physical Geography Laboratory (LAGEF), Department of Geography, Niterói 24210-340, -
NOTES and CORRESPONDENCE Synoptic-Scale Controls of Summer
15 FEBRUARY 2006 NOTES AND CORRESPONDENCE 613 NOTES AND CORRESPONDENCE Synoptic-Scale Controls of Summer Precipitation in the Southeastern United States JEREMY E. DIEM Department of Anthropology and Geography, Georgia State University, Atlanta, Georgia (Manuscript received 15 October 2004, in final form 11 August 2005) ABSTRACT Past climatological research has not quantitatively defined the synoptic-scale circulation deviations re- sponsible for anomalous summer-season precipitation totals in the southeastern United States. Therefore, the objectives of this research were to determine the synoptic-scale controls of wet and dry multiday periods during the summer within a portion of the southeastern United States as well as to assess the linkages between synoptic-scale circulation and multidecadal variations in precipitation characteristics for the study domain. Daily precipitation data from 30 stations for June, July, and August from 1953 to 2002 were converted into 13-day totals. Using standardized principal components analysis (PCA), the study domain was divided into three precipitation regions (i.e., South, Northwest, and Northeast). Wet and dry periods for each region were composed of the top 56 and bottom 56 thirteen-day periods. Composite circulation maps for 500 and 850 mb revealed the following: wet periods were generally associated with an upper-level trough over the interior southeastern United States coincident with strong lower-tropospheric flow into the South- east from the Gulf of Mexico, and dry periods were characterized by ridges or anticyclones over the midwestern and southeastern United States coupled with weak lower-tropospheric flow. Many of the wet periods had surface fronts. Over the 50-yr period, increased precipitation was significantly correlated with increased occurrences of midtropospheric troughs over the study domain. -
1 Climatology of South American Seasonal Changes
Vol. 27 N° 1 y 2 (2002) 1-30 PROGRESS IN PAN AMERICAN CLIVAR RESEARCH: UNDERSTANDING THE SOUTH AMERICAN MONSOON Julia Nogués-Paegle 1 (1), Carlos R. Mechoso (2), Rong Fu (3), E. Hugo Berbery (4), Winston C. Chao (5), Tsing-Chang Chen (6), Kerry Cook (7), Alvaro F. Diaz (8), David Enfield (9), Rosana Ferreira (4), Alice M. Grimm (10), Vernon Kousky (11), Brant Liebmann (12), José Marengo (13), Kingste Mo (11), J. David Neelin (2), Jan Paegle (1), Andrew W. Robertson (14), Anji Seth (14), Carolina S. Vera (15), and Jiayu Zhou (16) (1) Department of Meteorology, University of Utah, USA, (2) Department of Atmospheric Sciences, University of California, Los Angeles, USA, (3) Georgia Institute of Technology; Earth & Atmospheric Sciences, USA (4) Department of Meteorology, University of Maryland, USA, (5) Laboratory for Atmospheres, NASA/Goddard Space Flight Center, USA, (6) Department of Geological and Atmospheric Sciences, Iowa State University, USA, (7) Department of Earth and Atmospheric Sciences, Cornell University, USA, (8) Instituto de Mecánica de Fluidos e Ingeniería Ambiental, Universidad de la República, Uruguay, (9) NOAA Atlantic Oceanographic Laboratory, USA, (10) Department of Physics, Federal University of Paraná, Brazil, (11) Climate Prediction Center/NCEP/NWS/NOAA, USA, (12) NOAA-CIRES Climate Diagnostics Center, USA, (13) Centro de Previsao do Tempo e Estudos de Clima, CPTEC, Brazil, (14) International Research Institute for Climate Prediction, Lamont Doherty Earth Observatory of Columbia University, USA, (15) CIMA/Departmento de Ciencias de la Atmósfera, University of Buenos Aires, Argentina, (16) Goddard Earth Sciences Technology Center, University of Maryland, USA. (Manuscript received 13 May 2002, in final form 20 January 2003) ABSTRACT A review of recent findings on the South American Monsoon System (SAMS) is presented. -
Synoptic-Scale Controls of Fog and Low Clouds in the Namib Desert: Response to Reviewer 1
Synoptic-scale controls of fog and low clouds in the Namib Desert: Response to Reviewer 1 Hendrik Andersen, Jan Cermak, Julia Fuchs, Peter Knippertz, Marco Gaetani, Julian Quinting, Sebastian Sippel, and Roland Vogt contact: [email protected] We would like to thank reviewer 1 for her/his careful review of the manuscript and her/his constructive criticism and valuable comments. Comments by the referee are colored in black, our replies or comments are colored in blue and italics. Using a 14-year period of reanalysis grids and backward trajectories, this study examines the impact of large-scale dynamics and thermodynamics on fog and low clouds (FLCs) over Namib. Specifically, the authors’ focus on two seasons when different FLC types are observed due to different synoptic-scale regimes. A main finding is that the mean sea level pressure (MSLP) field differs notably between clear and FLC days. To this end, the authors’ use a statistical model and MSLP fields to provide skillful prediction of FLCs up to one day in advance. A new conceptual model of the two different FLC regimes is developed to summarize findings and aid in future studies related to FLCs over Namib. In general, the scientific purpose is justified, the findings are important, and the paper is well-written; however, I do have concerns about some of the methods used. Overall, I think that the results are interesting and worthy of publication, and at this stage I suggest acceptance subject to major revisions. Major/general comments: 1. Use of MSLP, 2 m temperature, and 10 m winds to characterize synoptic-scale conditions This study relies on the assumption that near-surface (boundary layer) meteorological variables – specifically MSLP, 2 m temperature, and 10 m horizontal wind components – are representative of the large-scale dynamics. -
Weather, Current and Routing Brief the Clipper 11/12 Round the World
Weather, Current and Routing Brief The Clipper 11/12 Round the World Race Prepared for the Race Skippers by Simon Rowell 27th April 2011 1. Leg One - Europe to Rio de Janeiro (early August to mid September) 4 1.1. The Route 4 1.2. The Weather 6 1.2.1. The Iberian Peninsula to the Canaries 6 1.2.2. The Canaries 10 1.2.3. The Canaries to the ITCZ, via the Cape Verdes 11 1.2.4. The ITCZ in the Atlantic 13 1.2.5. The ITCZ to Cabo Frio 16 1.3. Currents 18 1.3.1. The Iberian Peninsula to the Equator 18 1.3.2. The Equator to Rio 20 2. Leg 2 – Rio de Janeiro to Cape Town (mid September to mid October) 22 2.1. The Route 22 2.2. The Weather 22 2.3. Currents 27 3. Leg 3 – Cape Town to Western Australia (October to November) 29 3.1. The Route 29 3.2. The Weather 30 3.2.1. Southern Indian Ocean Fronts 34 3.3. Currents 35 3.3.1 Currents around the Aghulas Bank 35 3.3.2 Currents in the Southern Indian Ocean 37 4. Leg 4 –Western Australia to Wellington to Eastern Australia (mid November to December) 4.1. The Route 38 4.2. The Weather 39 4.2.1. Cape Leeuwin to Tasmania 39 4.2.2. Tasmania to Wellington and then to Gold Coast 43 4.3. Currents 47 5. Leg 5 – Gold Coast to Singapore to Qingdao (early January to end of February) 48 5.1. -
Chapter 7 – Atmospheric Circulations (Pp
Chapter 7 - Title Chapter 7 – Atmospheric Circulations (pp. 165-195) Contents • scales of motion and turbulence • local winds • the General Circulation of the atmosphere • ocean currents Wind Examples Fig. 7.1: Scales of atmospheric motion. Microscale → mesoscale → synoptic scale. Scales of Motion • Microscale – e.g. chimney – Short lived ‘eddies’, chaotic motion – Timescale: minutes • Mesoscale – e.g. local winds, thunderstorms – Timescale mins/hr/days • Synoptic scale – e.g. weather maps – Timescale: days to weeks • Planetary scale – Entire earth Scales of Motion Table 7.1: Scales of atmospheric motion Turbulence • Eddies : internal friction generated as laminar (smooth, steady) flow becomes irregular and turbulent • Most weather disturbances involve turbulence • 3 kinds: – Mechanical turbulence – you, buildings, etc. – Thermal turbulence – due to warm air rising and cold air sinking caused by surface heating – Clear Air Turbulence (CAT) - due to wind shear, i.e. change in wind speed and/or direction Mechanical Turbulence • Mechanical turbulence – due to flow over or around objects (mountains, buildings, etc.) Mechanical Turbulence: Wave Clouds • Flow over a mountain, generating: – Wave clouds – Rotors, bad for planes and gliders! Fig. 7.2: Mechanical turbulence - Air flowing past a mountain range creates eddies hazardous to flying. Thermal Turbulence • Thermal turbulence - essentially rising thermals of air generated by surface heating • Thermal turbulence is maximum during max surface heating - mid afternoon Questions 1. A pilot enters the weather service office and wants to know what time of the day she can expect to encounter the least turbulent winds at 760 m above central Kansas. If you were the weather forecaster, what would you tell her? 2. -
North and South American Low-Level Jets
American Low Level jetS A Scientific Prospectus and Implementation Plan North and South American Low-Level Jets Draft, March 2001 Prepared by Julia Nogues-Paegle and Jan Paegle (University of Utah, USA) with con- tributions from Michael Douglas (NOAA/NSSL, USA), Matilde Nicolini, Carolina Vera (University of Buenos Aires, Argentina), Jose Marengo (CPTEC, Brazil), Rene Garreaud (University of Chile, Chile), James Shuttleworth (University of Arizona, USA), C. Roberto Mechoso (UCLA, USA) and E. Hugo Berbery (University of Mary- land, USA). TABLE OF CONTENTS Executive Summary 5 1. What is the ALLS program? 6 2. Why the American Jets? 9 3. Science Objectives 11 3.1 Identify LLJ events and variability 11 3.1.1. North America 11 3.1.2. South America 14 3.2 Quantify LLJ contributions to the hydrological cycle 16 3.2.1. North America 16 3.2.2. South America 17 3.3 Determine plateau effects 19 3.3.1. North America 19 3.3.2. South America 19 3.4 Develop and validate theories on LLJ generation and variability 21 3.4.1. North America 21 3.4.2. South America 22 3.4.3 Local and remote influences on ALLS in relation 23 to droughts and floods 4. Implementation Plan 26 4.1 Numerical Modelling 26 4.2 Diagnostic Studies 29 4.3 Field Component of ALLS 30 4.3.1. Region of focus for the ALLS South American Field Program 32 4.3.2. Radiosonde network 33 4.3.3. Pilot balloon observations 35 4.3.4. Wind profiler observations 35 4.3.5. -
ERTH 365 - Lecture 8 Notes
1 Yoon Chang Kimberly Le ERTH 365 - Lecture 8 Notes Topics Discussed - Further processes for warming and cooling the atmosphere - Cold and warm core low pressure systems; - Hurricanes in depth - Hurricane Harvey review for Homework 2 (suppl. Notes) Warming & Cooling the atmosphere - other processes ● Another way of WARMING air ○ Physicists tell us that when water vapor condenses, a certain amount of thermal energy is “given” to the atmosphere. In short, condensation is a warming process. ○ The amount of heating is proportional to the amount of water that condenses. At sea-level temperatures and pressures, the warming is about 590 calories for each gram of water that condenses. The 590 calories is known as “latent heat.” ○ Since air with 100% relative humidity at lower dewpoint temperatures holds less water vapor than air with 100% relative humidity at higher dewpoint temperatures, much more heat is liberated in cases for which cloud development is occurring in high dewpoint environments. ● Another way of COOLING air ○ Conductional Cooling ■ Air flows over a cold surface and is cooled by conduction. (this process is termed “advective cooling”) If the cooling is sufficient to take the air parcel’s temperature to the dew point, the resulting condensation will produce a layered cloud on the ground. ■ Air “sits” on a surface that gets cold overnight. (radiation cooling) if the cooling is sufficient to take the air parcel’s temperature to the 2 dew point, the resulting condensation will produce a layered cloud on the ground. ○ Expansion cooling ■ Air expands, molecules get “further apart”, do not strike each other as often, do not “vibrate” as much.