An Observational Analysis Quantifying the Distance of Supercell-Boundary Interactions in the Great Plains
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
The Generation of a Mesoscale Convective System from Mountain Convection
JUNE 1999 TUCKER AND CROOK 1259 The Generation of a Mesoscale Convective System from Mountain Convection DONNA F. T UCKER Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas N. ANDREW CROOK National Center for Atmospheric Research Boulder, Colorado (Manuscript received 18 November 1997, in ®nal form 13 July 1998) ABSTRACT A mesoscale convective system (MCS) that formed just to the east of Denver is investigated with a nonhy- drostatic numerical model to determine which processes were important in its initiation. The MCS developed from out¯ow from previous convective activity in the Rocky Mountains to the west. Model results indicate that this out¯ow was necessary for the development of the MCS even though a convergence line was already present in the area where the MCS developed. A simulation with a 3-km grid spacing more fully resolves the convective activity in the mountains but the development of the MCS can be simulated with a 6.67-km grid. Cloud effects on solar radiation and ice sedimentation both in¯uence the strength of the out¯ow from the mountain convection but only the ice sedimentation makes a signi®cant impact on the development of the MCS after its initiation. The frequent convective activity in the Rocky Mountains during the warm season provides out¯ow that would make MCS generation favorable in this region. Thus, there is a close connection between mountain convective activity and MCS generation. The implications of such a connection are discussed and possible directions of future research are indicated. 1. Introduction scale or mesoscale. Forced lifting always occurs on the windward side of mountains; however, the mechanisms Mesoscale convective systems (MCSs) commonly de- that promote lifting on the downwind side of mountains, velop in the central United States during the warm sea- where a large proportion of MCSs initiate, are not as son, accounting for 30%±70% of the summer precipi- obvious. -
The Impact of Outflow Environment on Tropical Cyclone Intensification And
VOLUME 68 JOURNAL OF THE ATMOSPHERIC SCIENCES FEBRUARY 2011 The Impact of Outflow Environment on Tropical Cyclone Intensification and Structure ERIC D. RAPPIN Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida MICHAEL C. MORGAN AND GREGORY J. TRIPOLI University of Wisconsin—Madison, Madison, Wisconsin (Manuscript received 3 October 2008, in final form 5 June 2009) ABSTRACT In this study, the impacts of regions of weak inertial stability on tropical cyclone intensification and peak strength are examined. It is demonstrated that weak inertial stability in the outflow layer minimizes an energy sink of the tropical cyclone secondary circulation and leads to more rapid intensification to the maximum potential intensity. Using a full-physics, three-dimensional numerical weather prediction model, a symmetric distribution of environmental inertial stability is generated using a variable Coriolis parameter. It is found that the lower the value of the Coriolis parameter, the more rapid the strengthening. The lower-latitude simulation is shown to have a significantly stronger secondary circulation with intense divergent outflow against a com- paratively weak environmental resistance. However, the impacts of differences in the gradient wind balance between the different latitudes on the core structure cannot be neglected. A second study is then conducted using an asymmetric inertial stability distribution generated by the presence of a jet stream to the north of the tropical cyclone. The initial intensification is similar, or even perhaps slower, in the presence of the jet as a result of increased vertical wind shear. As the system evolves, convective outflow from the tropical cyclone modifies the jet resulting in weaker shear and more rapid intensification of the tropical cyclone–jet couplet. -
Mechanisms for Organization and Echo Training in a Flash-Flood-Producing Mesoscale Convective System
1058 MONTHLY WEATHER REVIEW VOLUME 143 Mechanisms for Organization and Echo Training in a Flash-Flood-Producing Mesoscale Convective System JOHN M. PETERS AND RUSS S. SCHUMACHER Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado (Manuscript received 19 February 2014, in final form 18 December 2014) ABSTRACT In this research, a numerical simulation of an observed training line/adjoining stratiform (TL/AS)-type mesoscale convective system (MCS) was used to investigate processes leading to upwind propagation of convection and quasi-stationary behavior. The studied event produced damaging flash flooding near Dubuque, Iowa, on the morning of 28 July 2011. The simulated convective system well emulated characteristics of the observed system and produced comparable rainfall totals. In the simulation, there were two cold pool–driven convective surges that exited the region where heavy rainfall was produced. Low-level unstable flow, which was initially convectively in- hibited, overrode the surface cold pool subsequent to these convective surges, was gradually lifted to the point of saturation, and reignited deep convection. Mechanisms for upstream lifting included persistent large-scale warm air advection, displacement of parcels over the surface cold pool, and an upstream mesolow that formed between 0500 and 1000 UTC. Convection tended to propagate with the movement of the southeast portion of the outflow boundary, but did not propagate with the southwest outflow boundary. This was explained by the vertical wind shear profile over the depth of the cold pool being favorable (unfavorable) for initiation of new convection along the southeast (southwest) cold pool flank. A combination of a southward-oriented pressure gradient force in the cold pool and upward transport of opposing southerly flow away from the boundary layer moved the outflow boundary southward. -
Outflow from a Nocturnal Thunderstorm
State Water Survey Division METEOROLOGY SECTION AT THE UNIVERSITY OF ILLINOIS SWS Contract Report 242 OUTFLOW FROM A NOCTURNAL THUNDERSTORM Robert W. Scott Meteorology Section Illinois State Water Survey Technical Report 3 NSF Grant ATM 78-08865 Low Level Convergence and the Prediction of Convective Precipitation November 1980 Champaign IL 61820 The project "Low-level Convergence and the Prediction of Convective Precipitation" is a coordinated research effort by the State Water Survey Division of the Illinois Institute of Natural Resources, the Off ice of Weather Modification Research in the National Oceanic and Atmospheric Adminis tration, and the Department of Environmental Sciences of the University of Virginia. Support of this research has been provided to the State Water Survey by the Atmospheric Research Section, National Science Founda tion, through grant ATM-78-08865. This award includes funds from the Army Research Office and the Air Force Office of Scientific Research of the Department of Defense. OUTFLOW FROM A NOCTURNAL THUNDERSTORM Robert W. Scott Illinois State Water Survey TABLE OF CONTENTS Page LIST OF FIGURES iii ABSTRACT .. v ACKNOWLEDGMENTS vii INTRODUCTION 1 STORM CONDITIONS 2 METEOROLOGICAL FIELDS IN THE NETWORK 8 DISCUSSION 19 REFERENCES 26 -iii- LIST OF FIGURES Figure Page 1 Synoptic analyses on 8-9 August 1979. a. Surface chart at 1900 CDT on 8 August 1979. b. Surface chart at 0700 CDT on 9 August 1979 3 c. 850-mb chart at 1900 CDT on 8 August 1979. d. 850-mb chart at 0700 CDT on 9 August 1979 4 e. 700-mb chart at 1900 CDT on 8 August 1979. -
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. -
A Targeted Modeling Study of the Interaction Between a Supercell and a Preexisting Airmass Boundary
University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Dissertations & Theses in Earth and Earth and Atmospheric Sciences, Department Atmospheric Sciences of 5-2010 A Targeted Modeling Study of the Interaction Between a Supercell and a Preexisting Airmass Boundary Jennifer M. Laflin University of Nebraska at Lincoln, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/geoscidiss Part of the Earth Sciences Commons Laflin, Jennifer M., "A Targeted Modeling Study of the Interaction Between a Supercell and a Preexisting Airmass Boundary" (2010). Dissertations & Theses in Earth and Atmospheric Sciences. 6. https://digitalcommons.unl.edu/geoscidiss/6 This Article is brought to you for free and open access by the Earth and Atmospheric Sciences, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Dissertations & Theses in Earth and Atmospheric Sciences by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. A TARGETED MODELING STUDY OF THE INTERACTION BETWEEN A SUPERCELL AND A PREEXISTING AIRMASS BOUNDARY by Jennifer M. Laflin A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree Master of Science Major: Geosciences Under the Supervision of Professor Adam L. Houston Lincoln, Nebraska May, 2010 A TARGETED MODELING STUDY OF THE INTERACTION BETWEEN A SUPERCELL AND A PREEXISTING AIRMASS BOUNDARY Jennifer Meghan Laflin, M. S. University of Nebraska, 2010 Adviser: Adam L. Houston It is theorized that supercell thunderstorms account for the majority of significantly severe convective weather which occurs in the United States, and as a result, it is necessary that the mechanisms which tend to produce supercells are recognized and investigated. -
Radar Artifacts and Associated Signatures, Along with Impacts of Terrain on Data Quality
Radar Artifacts and Associated Signatures, Along with Impacts of Terrain on Data Quality 1.) Introduction: The WSR-88D (Weather Surveillance Radar designed and built in the 80s) is the most useful tool used by National Weather Service (NWS) Meteorologists to detect precipitation, calculate its motion, estimate its type (rain, snow, hail, etc) and forecast its position. Radar stands for “Radio, Detection, and Ranging”, was developed in the 1940’s and used during World War II, has gone through numerous enhancements and technological upgrades to help forecasters investigate storms with greater detail and precision. However, as our ability to detect areas of precipitation, including rotation within thunderstorms has vastly improved over the years, so has the radar’s ability to detect other significant meteorological and non meteorological artifacts. In this article we will identify these signatures, explain why and how they occur and provide examples from KTYX and KCXX of both meteorological and non meteorological data which WSR-88D detects. KTYX radar is located on the Tug Hill Plateau near Watertown, NY while, KCXX is located in Colchester, VT with both operated by the NWS in Burlington. Radar signatures to be shown include: bright banding, tornadic hook echo, low level lake boundary, hail spikes, sunset spikes, migrating birds, Route 7 traffic, wind farms, and beam blockage caused by terrain and the associated poor data sampling that occurs. 2.) How Radar Works: The WSR-88D operates by sending out directional pulses at several different elevation angles, which are microseconds long, and when the pulse intersects water droplets or other artifacts, a return signal is sent back to the radar. -
Mesoscale Convective Complexes: an Overview by Harold Reynolds a Report Submitted in Conformity with the Requirements for the De
Mesoscale Convective Complexes: An Overview By Harold Reynolds A report submitted in conformity with the requirements for the degree of Master of Science in the University of Toronto © Harold Reynolds 1990 Table of Contents 1. What is a Mesoscale Convective Complex?........................................................................................ 3 2. Why Study Mesoscale Convective Complexes?..................................................................................3 3. The Internal Structure and Life Cycle of an MCC...............................................................................4 3.1 Introduction.................................................................................................................................... 4 3.2 Genesis........................................................................................................................................... 5 3.3 Growth............................................................................................................................................6 3.4 Maturity and Decay........................................................................................................................ 7 3.5 Heat and Moisture Budgets............................................................................................................ 8 4. Precipitation......................................................................................................................................... 8 5. Mesoscale Warm-Core Vortices....................................................................................................... -
Tropical Cyclone Tauktae
Tropical Cyclone Tauktae - Estimated Impacts Warning 7, 15 May 2021 2100 UTC PDC-1I-7A JTWC Summary: TROPICAL CYCLONE 01A (TAUKTAE), LOCATED APPROXIMATELY 263 NM SOUTH OF MUMBAI, INDIA, HAS TRACKED NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS.ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM CONTINUED TO CONSOLIDATE AND HAS BECOME MORE SYMMETRICAL WITH A DEEPENING CENTRAL DENSE OVERCAST AND AN EVOLVING EYE FEATURE.THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE LOW LEVEL CIRCULATION FEATURE IN THE 151703Z AMSU-B 89GHZ PASS AND COMPOSITE WEATHER RADAR LOOP FROM GOA, INDIA.THE INITIAL INTENSITY 65 KNOTS IS BASED ON THE PGTW DVORAK ESTIMATE OF T4.0/65KTS AND ADT OF T3.9/63KTS.THE UPPER-LEVEL ANALYSIS INDICATES FAVORABLE ENVIRONMENTAL CONDITIONS WITH ROBUST POLEWARD OUTFLOW, LOW VERTICAL WIND SHEAR (10-15KTS), AND WARM (31C) SEA SURFACE TEMPERATURE.TC 01A IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST AND WILL CONTINUE ON ITS CURRENT TRACK THROUGH TAU 36.AFTERWARD, IT WILL TRACK MORE NORTHWARD AND ROUND THE RIDGE AXIS BEFORE MAKING LANDFALL NEAR VERAVAL, INDIA SHORTLY AFTER TAU 48.THE POSSIBILITY OF RAPID INTENSIFICATION (RI) REMAINS HIGH DURING THE NEXT 24 TO 36 HOURS AS THE ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE, REACHING A PEAK INTENSITY OF 105 KNOTS BY TAU 36.AFTERWARD, THE SYSTEM WILL BEGIN TO WEAKEN WITH LAND INTERACTION.AFTER LANDFALL, THE CYCLONE WILL RAPIDLY ERODE AS IT TRACKS ACROSS THE RUGGED TERRAIN, LEADING TO DISSIPATION BY TAU 120, POSSIBLY -
PRELUDE at 4:30 A.M. on June 29, I Began My Day with a Quick Look at the Weather Charts and Prepared to Make a Forecast. It
PRELUDE At 4:30 a.m. on June 29, I began my day with a quick look at the weather charts and prepared to make a forecast. It was to be yet another hot day across the region; you did not need a meteorologist to tell you that it would be hot because, you could feel already it before the sun ever rose. The morning air was thick, heavy and the winds offered no relief, they merely stirred the soupy air in the kettle of the Great Lakes. I knew that thunderstorms were expected that day, I had been eyeing a system on the charts for the past three days, and it was to arrive during the late afternoon across the region I forecasted for (Cleveland, Ohio; Erie, Pennsylvania; Fort Wayne, Indiana; and Toledo, Ohio). I remember vividly making the comment “You’re going to need a big [weather] event to push this heat back” on my website’s morning forecast update. Little was I prepared that the event would be a derecho – an event that squall-line lovers, like myself, adore. Lucille was returning from Chicago, Illinois on her way back to Lima, Ohio, so I had to watch the weather of northern Indiana since I was expecting thunderstorms. I was located in Bowling Green, Ohio – a town which is no stranger to straight line winds from the squall lines that inhabit our world in the summer time. To our south was the city of Findlay, Ohio, where Kelly and her church were located near the downtown region, a city where their biggest weather event was the semi-decadal floods that occur along the banks of the Blanchard River. -
Glossary of Severe Weather Terms
Glossary of Severe Weather Terms -A- Anvil The flat, spreading top of a cloud, often shaped like an anvil. Thunderstorm anvils may spread hundreds of miles downwind from the thunderstorm itself, and sometimes may spread upwind. Anvil Dome A large overshooting top or penetrating top. -B- Back-building Thunderstorm A thunderstorm in which new development takes place on the upwind side (usually the west or southwest side), such that the storm seems to remain stationary or propagate in a backward direction. Back-sheared Anvil [Slang], a thunderstorm anvil which spreads upwind, against the flow aloft. A back-sheared anvil often implies a very strong updraft and a high severe weather potential. Beaver ('s) Tail [Slang], a particular type of inflow band with a relatively broad, flat appearance suggestive of a beaver's tail. It is attached to a supercell's general updraft and is oriented roughly parallel to the pseudo-warm front, i.e., usually east to west or southeast to northwest. As with any inflow band, cloud elements move toward the updraft, i.e., toward the west or northwest. Its size and shape change as the strength of the inflow changes. Spotters should note the distinction between a beaver tail and a tail cloud. A "true" tail cloud typically is attached to the wall cloud and has a cloud base at about the same level as the wall cloud itself. A beaver tail, on the other hand, is not attached to the wall cloud and has a cloud base at about the same height as the updraft base (which by definition is higher than the wall cloud). -
Midlevel Ventilation's Constraint on Tropical Cyclone Intensity Brian
Midlevel Ventilation’s Constraint on Tropical Cyclone Intensity by Brian Hong-An Tang B.S. Atmospheric Science, University of California Los Angeles, 2004 B.S. Applied Mathematics, University of California Los Angeles, 2004 Submitted to the Department of Earth, Atmospheric and Planetary Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Atmospheric Science at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY September 2010 c Massachusetts Institute of Technology 2010. All rights reserved. Author.............................................. ................ Department of Earth, Atmospheric and Planetary Sciences June 14, 2010 Certified by.......................................... ................ Kerry A. Emanuel Breene M. Kerr Professor of Atmospheric Science Director, Program in Atmospheres, Oceans and Climate Thesis Supervisor Accepted by.......................................... ............... Maria Zuber Earle Griswold Professor of Geophysics and Planetary Science Head, Department of Earth, Atmospheric and Planetary Sciences 2 Midlevel Ventilation’s Constraint on Tropical Cyclone Intensity by Brian Hong-An Tang Submitted to the Department of Earth, Atmospheric and Planetary Sciences on June 14, 2010, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Atmospheric Science Abstract Midlevel ventilation, or the flux of low-entropy air into the inner core of a tropical cyclone (TC), is a hypothesized mechanism by which environmental vertical wind shear can constrain a TC’s intensity. An idealized framework is developed to assess how ventilation affects TC intensity via two pathways: downdrafts outside the eyewall and eddy fluxes directly into the eyewall. Three key aspects are found: ventilation has a detrimental effect on TC intensity by decreasing the maximum steady state intensity, imposing a minimum intensity below which a TC will unconditionally decay, and providing an upper ventilation bound beyond which no steady TC can exist.