1. QLCS Storm-Scale Interrogation and Warning Considerations
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Storm Environment
August 4th, 2008 Chicago Derecho Tim Halbach – NWS Chicago Ron Przybylinski – NWS St. Louis Advanced Spotter Training-March 14, 2009 Event Overview y Progressive Derecho developed in eastern Iowa/northwest Illinois and caused widespread damage and power outages across northern Illinois and Indiana y Dissipated over West Virginia y Worst damage occurred north of the apex of the bow where multiple mesovorticies developed y Well developed convective system featuring a long lived Book-End Vortex and Rear Inflow Jet y Strong winds persisted well after the leading edge of the derecho • very low RIJ? y 6 tornadoes were confirmed via storm surveys y Griffith, IN: EF2 y Bloomingdale, IL: EF1 (2 Tornadoes) y Bolingbrook, IL: EF1 y Orland Park, IL: EF0 y Boswell, IN: EF0 Storm Environment 250 MB 3pm CDT Surface Map Forecast NAM Bufr Soundings- 21z at ORD Severe Thunderstorm Watches Nested Storm Based Warning Sectorization y Used a nested storm based warning sectorization for this event y 2 Meteorologists issuing severe warnings y 1 Meteorologist issuing tornado warnings Radar Analysis of the 5 Main Rotations The 5 Rotations Mesovort #1 y Developed along the Ogle/Carroll County line y Strengthened near Mount Morris • straight-line wind damage w/no tornado y Grain bin blown down, phone tower knocked over, building leveled. y Rotation lasted for about 1 hour and traveled about 60 miles from Carroll County into northern De Kalb county The 5 Rotations Mesovort #1 The 5 Rotations Mesovort #1 The 5 Rotations Mesovort #1 y Strongest rotation near Mount Morris The 5 Rotations Mesovort #1 y 108.8 knots sampled at 5130ft Above Ground Level The 5 Rotations Mesovort #1 -Damage Pictures from Ogle County The 5 Rotations Mesovort #2 y Developed further to the south across north central De Kalb county. -
A 10-Year Radar-Based Climatology of Mesoscale Convective System Archetypes and Derechos in Poland
AUGUST 2020 S U R O W I E C K I A N D T A S Z A R E K 3471 A 10-Year Radar-Based Climatology of Mesoscale Convective System Archetypes and Derechos in Poland ARTUR SUROWIECKI Department of Climatology, University of Warsaw, and Skywarn Poland, Warsaw, Poland MATEUSZ TASZAREK Department of Meteorology and Climatology, Adam Mickiewicz University, Poznan, Poland, and National Severe Storms Laboratory, Norman, Oklahoma, and Skywarn Poland, Warsaw, Poland (Manuscript received 29 December 2019, in final form 3 May 2020) ABSTRACT In this study, a 10-yr (2008–17) radar-based mesoscale convective system (MCS) and derecho climatology for Poland is presented. This is one of the first attempts of a European country to investigate morphological and precipitation archetypes of MCSs as prior studies were mostly based on satellite data. Despite its ubiquity and significance for society, economy, agriculture, and water availability, little is known about the climatological aspects of MCSs over central Europe. Our results indicate that MCSs are not rare in Poland as an annual mean of 77 MCSs and 49 days with MCS can be depicted for Poland. Their lifetime ranges typically from 3 to 6 h, with initiation time around the afternoon hours (1200–1400 UTC) and dissipation stage in the evening (1900–2000 UTC). The most frequent morphological type of MCSs is a broken line (58% of cases), then areal/cluster (25%), and then quasi- linear convective systems (QLCS; 17%), which are usually associated with a bow echo (72% of QLCS). QLCS are the feature with the longest life cycle. -
Tropical Cyclone Mesoscale Circulation Families
DOMINANT TROPICAL CYCLONE OUTER RAINBANDS RELATED TO TORNADIC AND NON-TORNADIC MESOSCALE CIRCULATION FAMILIES Scott M. Spratt and David W. Sharp National Weather Service Melbourne, Florida 1. INTRODUCTION Doppler (WSR-88D) radar sampling of Tropical Cyclone (TC) outer rainbands over recent years has revealed a multitude of embedded mesoscale circulations (e.g. Zubrick and Belville 1993, Cammarata et al. 1996, Spratt el al. 1997, Cobb and Stuart 1998). While a majority of the observed circulations exhibited small horizontal and vertical characteristics similar to extra- tropical mini supercells (Burgess et al. 1995, Grant and Prentice 1996), some were more typical of those common to the Great Plains region (Sharp et al. 1997). During the past year, McCaul and Weisman (1998) successfully simulated the observed spectrum of TC circulations through variance of buoyancy and shear parameters. This poster will serve to document mesoscale circulation families associated with six TC's which made landfall within Florida since 1994. While tornadoes were not associated with all of the circulations (manual not algorithm defined), those which exhibited persistent and relatively strong rotation did often correlate with touchdowns (Table 1). Similarities between tornado- producing circulations will be discussed in Section 7. Contained within this document are 0.5 degree base reflectivity and storm relative velocity images from the Melbourne (KMLB; Gordon, Erin, Josephine, Georges), Jacksonville (KJAX; Allison), and Eglin Air Force Base (KEVX; Opal) WSR-88D sites. Arrows on the images indicate cells which produced persistent rotation. 2. TC GORDON (94) MESO CHARACTERISTICS KMLB radar surveillance of TC Gordon revealed two occurrences of mesoscale families (first period not shown). -
The Initiation and Evolution of a Mini-Bow Echo Occurring Behind a Prefrontal Squall Line
THE INITIATION AND EVOLUTION OF A MINI-BOW ECHO OCCURRING BEHIND A PREFRONTAL SQUALL LINE Alan E. Gerard NOAA/National Weather Service Forecast Office Jackson, Mississippi Corey M. Mead NOAA/National Weather Service Forecast Office OmahalValley, Nebraska Abstract tern, as well as shear zones and circulations along the leading edge of the convection, were observed by the Early on 13 April 1996, a mini-bow echo moved Jackson, Mississippi (KJAN) WSR-88D. through parts of south central Mississippi. This bow echo produced one report of severe weather, namely $10K in 2. Synoptic Environment wind damage near the town of Bassfield in Jefferson Davis county. The evolution of this bow echo was some During the early evening hours of 12 April 1996, syn what unusual, in that the storm developed within the optic features and parameters came together for an active southern part of the enhanced stratiform rain region of a severe weather event over the western Gulf Coast region well developed prefrontal squall line. This paper will (Fig. 2). At 0000 UTC 13 April 1996, an upper-level short examine the development of this small bow echo, begin wave trough had become negatively-tilted over north ning with the synoptic and mesoscale environments. This Texas as a 30 m s'! 500 mb wind maximum lifted out ofthe will be followed by the storm evolution as observed by the base of the trough and into the mid-Mississippi valley WSR-88D Doppler radar in Jackson, Mississippi. region. A 300 mb polar jet streak in excess of 50 m s'! was located downstream from the trough axis from eastern 1. -
Storm Spotting – Solidifying the Basics PROFESSOR PAUL SIRVATKA COLLEGE of DUPAGE METEOROLOGY Focus on Anticipating and Spotting
Storm Spotting – Solidifying the Basics PROFESSOR PAUL SIRVATKA COLLEGE OF DUPAGE METEOROLOGY HTTP://WEATHER.COD.EDU Focus on Anticipating and Spotting • What do you look for? • What will you actually see? • Can you identify what is going on with the storm? Is Gilbert married? Hmmmmm….rumor has it….. Its all about the updraft! Not that easy! • Various types of storms and storm structures. • A tornado is a “big sucky • Obscuration of important thing” and underneath the features make spotting updraft is where it forms. difficult. • So find the updraft! • The closer you are to a storm the more difficult it becomes to make these identifications. Conceptual models Reality is much harder. Basic Conceptual Model Sometimes its easy! North Central Illinois, 2-28-17 (Courtesy of Matt Piechota) Other times, not so much. Reality usually is far more complicated than our perfect pictures Rain Free Base Dusty Outflow More like reality SCUD Scattered Cumulus Under Deck Sigh...wall clouds! • Wall clouds help spotters identify where the updraft of a storm is • Wall clouds may or may not be present with tornadic storms • Wall clouds may be seen with any storm with an updraft • Wall clouds may or may not be rotating • Wall clouds may or may not result in tornadoes • Wall clouds should not be reported unless there is strong and easily observable rotation noted • When a clear slot is observed, a well written or transmitted report should say as much Characteristics of a Tornadic Wall Cloud • Surface-based inflow • Rapid vertical motion (scud-sucking) • Persistent • Persistent rotation Clear Slot • The key, however, is the development of a clear slot Prof. -
Mt417 – Week 10
Mt417 – Week 10 Use of radar for severe weather forecasting Single Cell Storms (pulse severe) • Because the severe weather happens so quickly, these are hard to warn for using radar • Main Radar Signatures: i) Maximum reflectivity core developing at higher levels than other storms ii) Maximum top and maximum reflectivity co- located iii) Rapidly descending core iv) pure divergence or convergence in velocity data Severe cell has its max reflectivity core higher up Z With a descending reflectivity core, you’d see the reds quickly heading down toward the ground with each new scan (typically around 5 minutes apart) Small Scale Winds - Divergence/Convergence - Divergent Signature Often seen at storm top level or near the Note the position of the radar relative to the ground at close velocity signatures. This range to a pulse type is critical for proper storm interpretation of the small scale velocity data. Convergence would show colors reversed Multicells (especially QLCSs– quasi-linear convective systems) • Main Radar Signatures i) Weak echo region (WER) or overhang on inflow side with highest top for the multicell cluster over this area (implies very strong updraft) ii) Strong convergence couplet near inflow boundary Weak Echo Region (left: NWS Western Region; right: NWS JETSTREAM) • Associated with the updraft of a supercell thunderstorm • Strong rising motion with the updraft results in precipitation/ hail echoes being shifted upward • Can be viewed on one radar surface (left) or in the vertical (schematic at right) Crude schematic of -
A Revised Tornado Definition and Changes in Tornado Taxonomy
1256 WEATHER AND FORECASTING VOLUME 29 A Revised Tornado Definition and Changes in Tornado Taxonomy ERNEST M. AGEE Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana (Manuscript received 4 June 2014, in final form 30 July 2014) ABSTRACT The tornado taxonomy presented by Agee and Jones is revised to account for the new definition of a tor- nado provided by the American Meteorological Society (AMS) in October 2013, resulting in the elimination of shear-driven vortices from the taxonomy, such as gustnadoes and vortices in the eyewall of hurricanes. Other relevant research findings since the initial issuance of the taxonomy are also considered and in- corporated, where appropriate, to help improve the classification system. Multiple misoscale shear-driven vortices in a single tornado event, when resulting from an inertial instability, are also viewed to not meet the definition of a tornado. 1. Introduction and considerations from a cumuliform cloud, and often visible as a funnel cloud and/or circulating debris/dust at the ground.’’ In The first proposed tornado taxonomy was presented view of the latest definition, a few changes are warranted by Agee and Jones (2009, hereafter AJ) consisting of in the AJ taxonomy. Considering the roles played by three types and 15 species, ranging from the type I buoyancy and shear on a variety of spatial and temporal (potentially strong and violent) tornadoes produced by scales (from miso to meso to synoptic), coupled with the the classic supercell, to the more benign type III con- requirement in the latest definition that a tornado must vective and shear-driven vortices such as landspouts and be pendant from a cumuliform cloud, it is necessary to gustnadoes. -
Straig H T-Line W in Ds
Straight Straight-Line Winds Straight-line winds are one of the most common hazards produced by both severe and non-severe thunderstorms. Depending on the organization of the storms, damage can be localized to just a few miles in area or in the case of exceptionally well-organized storms hundreds of miles in area. The - types of thunderstorms that most commonly produce a straight-line wind threat include large Line Winds Mesoscale Convective Systems (MCSs) and supercells. This help page highlights these different storms types, wind shifts, and how to diagnose these features using radar. Thin Lines & Wind Shifts Radar reflectivity is a great tool for diagnosing fronts and wind shifts. Radar can see many different boundaries such as cold fronts, dry lines, and outflow boundaries due to the temperature and moisture differences in the air, which create a radar reflectivity feature known as a “thin line.” In the example to the right, the black ellipse indicates where a thin line is and the red arrows indicate a wind shift associated with a cold front. It is important to keep in mind that thin lines are only visible closer to a radar due to the radar beam overshooting surface fronts at farther distances from the radar. Supercells Even though supercell thunderstorms are often thought of as always producing tornadoes, only 20% of them actually produce tornadoes. Supercells can and do produce straight-line winds more often than tornadoes. In the example below this supercell produced a 70 mph wind gust near Blair, Oklahoma. Base Reflectivity data is on the left and Base Velocity data is on the right. -
Synoptic, Mesoscale and Radar Aspects of the Northeast Kansas Supercell of September 21, 1993
■© \r<J> QC 995 • U61 no.109 F c.2 OAA TECHNICAL MEMORANDUM NWS CR-109 ii SYNOPTIC, MESOSCALE AND RADAR ASPECTS OF THE NORTHEAST KANSAS SUPERCELL OF SEPTEMBER 21, 1993 Kenneth M. Labas National Weather Service Forecast Office (Chicago) Romeoville, Illinois Brian P. Walawender National Weather Service Forecast Office Topeka, Kansas October 1995 U.S DEPARTMENT OF / National Oceanic and / National Weather Commerce / Atmospheric Administration/ Service RECEIVED hdV 1 6 19S5 Director, Office of Meteorology NOAA TECHNICAL MEMORANDA National Weather Service, Central Region Subseries The National Weather Service Central Region (CR) subseries provides an informal medium for the documentation and quick dissemina tion of results not appropriate, or not yet ready, for formal publication. The series is used to report on work in progress, to describe technical procedures and practices, or to relate progress to a limited audience. These Technical Memoranda report on investigations devoted primarily to regional and local problems of interest mainly to regional personnel, and hence will not be widely distributed. Papers 1 through 15 are in the former series, ESSA Technical Memoranda, Central Region Technical Memoranda (CRTM); Papers 16 throigh 36 are in the former series, ESSA Technical Memoranda, Weather Bureau Technical Memoranda (WBTM). Beginning with Paper 37, the papers are part of the series, NOAA Technical Memoranda NWS. Papers that have a PB or COM number are available from the National Technical Information Service, U. S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22151. Order by accession number shown in parenthesis at the end of each entry. Prices vary for all paper copies. -
President'smessage
NWA NEWSLETTER No. 02-01 JANUARY 2002 PRESIDENT’S MESSAGE we as an organization are now, and the best course of action to take in the very near future. The NWA Strategic It is a great honor that you, the membership of the Planning Committee has been tackling these issues, National Weather Association, have chosen for me to including the development of an NWA Vision Statement. serve as your President for 2002. Our former presidents This group will be working quickly to provide information have taught me much, not just about meteorology, but for the 2002 officers and councilors to act on. leadership. The immediate-past president, Les Lemon has Since you the members are the most important piece of been an inspiration, mentor and friend. the NWA, we will look at ways to gain and retain The organization will be well served through the recent members. My goal for 2002 is to surpass the 3,000- election of officers and councilors to the NWA Council. member mark and I will be asking the Membership See the complete listing on page 3. The National Weather Committee to assist in developing a marketing plan to Association is grateful to all individuals that were on the reach out especially to our college meteorology students ballot. Without this volunteer spirit, the NWA simply and recent graduates. Our current membership has been could not exist. One voter wrote a note on the bottom of hovering around 2,800. We need to make the value of the ballot stating, “I wish I could vote for them all.” That membership in the NWA very clear to prospective says a great deal about the caliber of people willing to get members. -
THE BOW ECHO and MCV EXPERIMENT Observations and Opportunities
THE BOW ECHO AND MCV EXPERIMENT Observations and Opportunities BY CHRISTOPHER DAVIS, NOLAN ATKINS, DIANA BARTELS, LANCE BOSART, MICHAEL CONIGLIO, GEORGE BRYAN, WILLIAM COTTON, DAVID DOWELL, BRIAN JEWETT, ROBERT JOHNS,* DAVID JORGENSEN, JASON KNIEVEL, KEVIN KNUPP, WEN-CHAU LEE, GREGORY MCFARQUHAR, JAMES MOORE, RON PRZYBYLINSKI, ROBERT RAUBER, BRADLEY SMULL, ROBERT TRAPP, STANLEY TRIER, ROGER WAKIMOTO, MORRIS WEISMAN, AND CONRAD ZIEGLER The field campaign, involving multiple aircraft and ground-based instruments, documented numerous long-lived mesoscale convective systems, many producing strong surface winds and exhibiting mesoscale rotation. hile the observational study of mesoscale Kansas Preliminary Regional Experiment for convective systems (MCSs) has been active Stormscale Operational and Research Meteorology W since the 1940s (e.g., Newton 1950 and ref- (STORM)-Central (PRE-STORM) (Cunning 1986) erences within), until the Bow Echo and Mesoscale were geographically fixed by the ground-based instru- Convective Vortex Experiment (BAMEX) there were ment networks employed. The unique observing no studies designed to sample multiscale aspects of strategy of BAMEX relied on the deployment of these systems throughout the majority of their life highly mobile observing systems, both airborne and cycles. Previous field studies such as the Oklahoma- ground based, supported by the enhanced operational AFFILIATIONS: DAVIS, BRYAN, DOWELL, KNIEVEL, BARTELS, LEE, Missouri; SMULL—NSSL, and University of Washington, Seattle, TRIER, AND WEISMAN—National -
Southwestern Illinois Tornado Event June 1St, 1999
Southwestern Illinois Tornado Event Title of Event June 1st, 1999 (Calibri 20 pt. – BOLD) St. Louis All sections have a title Overview Calibri (Body) 16 pt. – BOLD Strong to severe thunderstorms moved across the bi-state region during the late afternoon and early evening June 1st, 1999. A number of these storms evolved into tornado producing supercells while other storms produced damaging winds and hail. This severe All of the descriptive text is written in storm event was rather challenging since three supercells containing moderate to strong mesocyclones moved from the southwest across the southwest sections of our County Calibri (Body) 11 pt. Warning Area (CWA) between 6:45 and 7:30 PM CDT. During this same period, three other supercells rapidly formed over the northeast quadrant of our CWA (far northeast General Ordering of Content Macoupin/northern Montgomery counties in Illinois). This case was particularly challenging since we were focusing our energies on nearly opposite ends of our CWA. Two of the three supercells to our southwest spawned tornadoes over Phelps and Crawford counties in 1) Overview Section giving a south-central Missouri. At nearly the same time, two of the three supercells over northern Montgomery county in central Illinois also produced two tornadoes (near or after 7:00 PM description of the event CDT). A fourth supercell rapidly formed after 7:40 PM CDT and developed yet another 2) Overview Map - damage tracks tornado over parts of eastern Fayette county Illinois just after 8:00 PM CDT. map, hail swath graphic,