Howard Bluestein

• University of Oklahoma

This study creates a composite sounding for nocturnal convection initiation (CI) events under weakly forced conditions and utilizes idealized numerical simulations to assess the impact of atmospheric bores on these environments. Thirteen soundings were used to create this composite sounding. Common conditions associated with these weakly forced env...

Plain Language Summary Both airborne and ground‐based weather radar measurements can be used to estimate snowflake characteristics such as their mean size. However, it is difficult to compare the radar‐estimated mean sizes between these platforms because of the vast methodological differences in how these sizes are estimated and the spatial and tem...

The focus of this work is to study storm regions which may be associated with a lightning channel using polarimetric weather radar. Previous studies show that strong electric fields induced by a lightning channel are capable of vertically aligning ice crystals above the melting layer, typically in the storm updraft region. This crystal alignment re...

Current observation systems that provide data for the analysis and prediction of climate and day-to-day weather are described, along with plans for future systems. The basic principles of satellite, radar, lidar, and sodar measurements are summarized. Temperature and moisture measurements on planetary and synoptic scales, ranging from satellites, t...

Mobile, polarimetric radar data were collected on a series of tornadoes that occurred near Dodge City, Kansas. A poststorm survey revealed a series of tornadic debris swaths in several dirt fields and high-resolution pictures of the tornado documented the visual characteristics of the tornado and the lofted debris cloud. The main rotational couplet...

This study builds upon recent rapid-scan radar observations of mesocyclonic tornadogenesis in supercells by investigating the formation of seven tornadoes (four from a single cyclic supercell), most of which include samples at heights < 100 m above radar level. The spatiotemporal evolution of the tornadic vortex signatures (TVSs), maximum velocity...

Ground‐based, mobile Doppler radars have been used for three decades to study the fine‐scale structure of tornadoes and their formation and evolution. A brief history of the different types of mobile radars according to wavelength, type of modulation, and kind of polarization is given, along with the special attributes and advantages each has. The...

On 24 May 2016, a supercell that produced 13 tornadoes near Dodge City, Kansas, was documented by a rapid-scanning, X-band, polarimetric, Doppler radar (RaXPol). The anomalous nature of this storm, particularly the significant deviations in storm motion from the mean flow and number of tornadoes produced, is examined and discussed. RaXPol observed...

Tornadic supercells moved across parts of Oklahoma on the afternoon and evening of 9 May 2016. One such supercell, while producing a long-lived tornado, was observed by nearby WSR-88D radars to contain a strong anticyclonic velocity couplet on the lowest elevation angle. This couplet was located in a very atypical position relative to the ongoing c...

Rapid-scan polarimetric data analysis of the dissipation of a likely violent supercell tornado that struck near Sulphur, OK on 9 May 2016 is presented. The Rapid X-band Polarimetric Radar was used to obtain data of the tornado at the end of its mature phase and during its entire dissipation phase. The analysis is presented in two parts: dissipation...

The maximum upward vertical velocity at the leading edge of a density current is commonly <10 m s−1. Studies of the vertical velocity, however, are relatively few, in part owing to the dearth of high spatiotemporal observations. During the Plains Elevated Convection at Night (PECAN) field project, a mobile Doppler lidar measured a maximum vertical...

This study presents an investigation into relationships among topographic elevation, surface land cover, and tornado intensity using rapid-scan, mobile Doppler radar observations of four tornadoes from the U.S. Central Plains. High spatiotemporal resolution observations of tornadic vortex signatures from the radar’s lowest elevation angle data (in...

A detailed damage survey is combined with high-resolution mobile, rapid-scanning X-band polarimetric radar data collected on the Shawnee, OK tornado of 19 May 2013. The focus of this study is the radar data collected during a period when the tornado was producing damage rated EF3. Vertical profiles of mobile radar data, centered on the tornado, rev...

This is a study of a tornadic supercell in Kansas on 14 May 2018 in which data of relatively high spatiotemporal resolution from a mobile, polarimetric, X-band, Doppler radar were integrated with GOES-16 geosynchronous satellite imagery, and with fixed-site, surveillance, S-band polarimetric Doppler radar data. The data-collection period spanned th...

This study documents the formation and part of the early evolution of a large, violent tornado near El Reno, Oklahoma, based on data from a mobile, polarimetric, rapid scan, X-band, Doppler radar. The main circulation associated with the tornado formed near the ground initially, ~90 s prior to the development of the vertically coherent vortex, whic...

Polarimetric measurements recorded by a mobile X-band radar are combined with photographs of the Dodge City, Kansas, tornado to quantitatively document the evolving debris cloud. An inner annulus or tube of high radar reflectivity encircled the tornado at low levels. A column of low cross-correlation coefficient rhv was centered on the funnel cloud...

The number of case studies in the literature of nocturnal convection has increased during the past decade, especially those that utilize high-spatiotemporal-resolution datasets from field experiments such as the International H2O Project (IHOP_2002) and Plains Elevated Convection at Night (PECAN). However, there are few case studies of events for c...

In many instances, synchronization of Doppler radar data among multiple platforms for multiple-Doppler analysis is challenging. This study describes the production of dual-Doppler wind analyses from several case studies using data from a rapid-scanning, X-band, polarimetric, Doppler radar-the RaXPol radar-and data from nearby WSR-88Ds. Of particula...

A three-dimensional data assimilation (3DVar) least squares-type single-Doppler velocity retrieval (SDVR) algorithm is utilized to retrieve the wind field of a tornadic supercell using data collected by a mobile, phased-array, Doppler radar [Mobile Weather Radar (MWR) 05XP] with very high temporal resolution (6 s). It is found that the cyclonic cir...

A recent study found that surface hodographs over the Great Plains of the United States turn in a counterclockwise direction with time. This observed turning is opposite of the clockwise turning observed (and expected, based on theory) at higher altitudes. Using a mesoscale forecast model, the same study shows that it has the same hodograph behavio...

Vertical shear in the boundary layer affects the mode of convective storms that can exist if they are triggered. In western portions of the southern Great Plains of the United States, vertical shear, in the absence of any transient features, changes diurnally in a systematic way, thus leading to a preferred time of day for the more intense modes of...

During the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) field campaign, mobile radars observed a previously undocumented feature: the low-reflectivity ribbon (LRR). The LRR was characterized by reduced reflectivity ZH and differential reflectivity ZDR through a narrow region extending from the intersection of the...

In the past four decades much has been discovered about tornado formation and structure from observations, laboratory models, and numerical-simulation experiments. Observations include nearby movies and photographs of tornadoes, fixed-site, airborne, and ground-based mobile Doppler radar remote measurements, and in situ measurements using instrumen...

With the development of multimoment bulk microphysical schemes and polarimetric radar forward operators, one can better examine convective storms simulated in high-resolution numerical models from a simulated polarimetric radar perspective. Subsequently, relationships between observable and unobservable quantities can be examined that may provide u...

The objectives of this study are to determine the fine-scale characteristics of the wind and temperature fields associated with a prefrontal wind-shift line and to contrast them with those associated with a strong cold front. Data from a mobile, polarimetric, X-band, Doppler radar and from a surveillance S-band radar, temperature profiles retrieved...

A high resolution numerical model and polarimetric forward operator allow one to examine simulated convective storms from the perspective of observable polarimetric radar quantities, enabling a better comparison of modeled and observed deep moist convection. Part I of this two-part study described the model and forward operator used for all simulat...

A nocturnal maximum in rainfall and thunderstorm activity over the central Great Plains has been widely documented, but the mechanisms for the development of thunderstorms over that region at night are still not well understood. Elevated convection above a surface frontal boundary is one explanation, but this study shows that many thunderstorms for...

During the afternoon of May 9, 2016, a scattered line of supercells formed along a dryline in western Oklahoma and produced a regional outbreak of tornadoes and other severe weather. Embedded between two of the large-strong-tall classic supercells was a smaller storm recognized after-the-fact as a mini-supercell (near Mill Creek, OK). The classic s...

High-resolution data of the tornadic debris signature (TDS) and weak-echo reflectivity band (WRB) associated with a large, violent tornado on 24 May 2011 in central Oklahoma are examined using a rapid-scan, X-band, polarimetric, mobile Doppler radar. Various characteristics of these features and their evolution are examined over time intervals of 2...

The United States experiences the most tornadoes of any country in the world. Given the catastrophic impact of tornadoes, concern has arisen regarding the variation in climatology of U.S. tornadoes under the changing climate. A recent study claimed that the temporal variability of tornado occurrence over the continental U.S. has increased since the...

A frequent area of waterspout formation is identified over the southern Aegean Sea. The objectives of this study are threefold: (1) to investigate the temporal evolution of Cloud Top Temperature (CTT) of cloud lines (waterspouts' parent clouds) that triggered the formation of single or multiple waterspout events, by using Meteorological Satellite S...

Past numerical simulation studies found that debris loading from sand-sized particles may substantially affect tornado dynamics, causing reductions in near-surface wind speeds up to 50%. To further examine debris loading effects, simulations are performed using a large-eddy simulation model with a two-way drag force coupling between air and sand. S...

Supercells dominated by mesocyclones, which tend to propagate to the right of the tropospheric pressure-weighted mean wind, on rare occasions produce anticyclonic tornadoes at the trailing end of the rear-flank gust front. More frequently, mesoanticyclones are found at this location, most of which do not spawn any tornadoes. In this paper, four cas...

A detailed damage survey of the El Reno, Oklahoma, tornado of 31 May 2013 combined with rapid-scanning data recorded from two mobile radars is presented. One of the radars was equipped with polarimetric capability. The relationship between several suction vortices visually identified in pictures with the high-resolution Doppler velocity data and sw...

Several data assimilation and forecast experiments are undertaken to determine the impact of special observations taken during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) on forecasts of the 5 June 2009 Goshen County, Wyoming, supercell. The data used in these experiments are those from the Mobile Weather Ra...

Recent studies revealed that convective weather favours the development of tornadoes, waterspouts and funnel clouds mainly over the western Greece. Besides the western Greece, the Athens city and its suburbs revealed to be another favour area for the development of less severe phenomena, too. The goal of this study is to detail the analyses of the...

A worth noting extreme meteorological conditions in Midwest states of United States of America (U.S.A.) lasting from 27 to 30 April 2014 triggered the scientific interest worldwide. A closed upper air low, associated with a closed cyclonic circulation and a frontal activity on the surface, moved through the Northern Plains towards the Midwest state...

Recent studies have shown that western Greece has been affected by numerous tornado events that caused significant impacts to the local society. On February 7, 2013, several tornadoes developed along western Greece, while the most intense event took place close to Ag. Ilias village, 8 km northwestern from Aitoliko city over western Greece. The torn...

Unique observations of the interaction and likely merger of two cyclonic tornadoes are documented. One of the tornadoes involved in the interaction was the enhanced Fujita scale (EF5) El Reno-Piedmont, Oklahoma, tornado from 24 May 2011 and the other was a previously undocumented tornado. Data from three S-band radars: Twin Lakes, Oklahoma (KTLX);...

This study presents rapid-scanning X-band polarimetric radar data combined with photogrammetry of the El Reno tornado of 31 May 2013. The relationship between the hook echo, weak-echo hole (WEH), weak-echo column (WEC), and the rotational couplet with the visual characteristics of the tornado are shown. For the first time, cross-correlation coeffic...

On 31 May 2013 a broad, intense, cyclonic tornado and a narrower, weaker companion anticyclonic tornado formed in a supercell in central Oklahoma. This paper discusses the synoptic- and mesoscale environment in which the parent storm formed, based on data from the operational network of surface stations, rawinsondes, and WSR-88D radars, and from th...

On 24 May 2011, a mobile, rapid-scan, X-band, polarimetric, Doppler radar (RaXPol) collected data on a supercell as it produced two tornadoes near El Reno, Oklahoma. The first tornado, rated an EF-3, was documented from intensification to decay, and the genesis and intensification of a second tornado that was rated an EF-5 was subsequently also doc...

This paper documents features that led to major forecast errors on the 12-24-h time scale in the nature and location of severe weather in the southern plains on 30 May 2012. Evidence is presented that the forecast errors were the result of 1) dry air that originated in a region of dissipating, elevated convective storms, and which was advected in a...

Emerging radar technologies best suited to addressing key scientific questions and future problems are identified and discussed. Future research with radar will involve multiplatform, multi-model investigations. There will be four major research themes involving radar. To address these scientific problems, radars will be needed on diverse platforms...

Observations collected in the second Verification of the Origins of Rotation in Tornadoes Experiment during a 15-min period of a supercell occurring on 18 May 2010 near Dumas, Texas, are presented. The primary data collection platforms include two Ka-band mobile Doppler radars, which collected a near-surface, short-baseline dual-Doppler dataset wit...

The increasing number of mobile Doppler radars used in field campaigns across the central United States has led to an increasing number of high-resolution radar datasets of strong tornadoes. There are more than a few instances in which the radar-measured radial velocities substantially exceed the estimated wind speeds associated with the enhanced F...

In this study, the climatology of tornadoes, waterspouts and funnel clouds over Greece is presented for the period 1709–2012. The climatology consists of two datasets. An historical dataset (1709–1999) is based on newspaper archives, historical archives, published tornado literature, administrative records and reports of Hellenic National Meteorolo...

A mobile, phased-array Doppler radar, the Mobile Weather Radar, 2005 X-band, Phased Array (MWR-05XP), has been used since 2007 to obtain data in supercells and tornadoes. Rapidly updating, volumetric data of tornadic vortex signatures (TVSs) associated with four tornadoes are used to investigate the time-height evolution of TVS intensity, position,...

Adding a mix of X- or C-band radars to the current Weather Surveillance Radar-1988 Doppler (WSR-88D) network could address several limitations of the network, including improvements to spatial gaps in low-level coverage and temporal sampling of volume scans. These limitations can result in missing critical information in highly dynamic events, such...

During the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2), in the spring of 2010, a mobile and pulsed Doppler lidar system [the Truck-Mounted Wind Observing Lidar Facility (TWOLF)] mounted on a truck along with a mobile, phased-array, X-band Doppler radar system [Mobile Weather Radar–2005 X-band, phased array (MWR-...

Observations from a hybrid phased-array Doppler radar, the Mobile Weather Radar, 2005 X-band, Phased Array (MWR-05XP), were used to investigate the vertical development of tornadic vortex signatures (TVSs) during supercell tornadogenesis. Data with volumetric update times of ;10 s, an order of magnitude better than that of most other mobile Doppler...

As part of the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) field campaign, a very high-resolution, mobile, W-band Doppler radar collected near-surface (200 m AGL) observations in an EF-0 tornado near Tribune, Kansas, on 25 May 2010 and in sub-tornado-strength vortices near Prospect Valley, Colorado, on 26 May 20...

A novel, rapid-scanning, X-band (3-cm wavelength), polarimetric (RaXPol), mobile radar was developed for severe-weather research. The radar employs a 2.4-m-diameter dual-polarized parabolic dish antenna on a high-speed pedestal capable of rotating the antenna at 180 degrees s(-1). The radar can complete a 10-elevation-step volume scan in about 20 s...

Tornadoes are rapidly rotating columns of air that make contact with the ground. In general we consider them to be intense, columnar vortices in contact with the ground that are capable of inflicting damage. They are either connected to or are situated underneath a cumuliform, buoyant convective cloud above (Figure 6.1). Tornadoes are sometimes, bu...

In the previous chapter, we considered the dynamics of (mostly) dry convection and found that buoyancy and dynamic pressure gradient forces are of fundamental importance. In addition, vertical shear was shown to be able to organize shallow convection into lines under some circumstances. We considered the inclusion of water substance only in how it...

In the early days of severe weather forecasting in the U. S. in the 1950s and 1960s, synoptic conditions associated with severe convection in the Great Plains and to the east were identified. For example, it was noted that a strong low-level southerly jet transporting moisture northward from the Gulf of Mexico surmounted by a more westerly jet alof...

In the previous chapter we considered the behavior of ordinary cells and multicell convective storms, which consist of a succession of ordinary cells for which positive buoyancy is of primary importance. This positive buoyancy is realized by air parcels accelerating upward in a conditionally unstable atmosphere, which is counteracted by a downward-...

When convective storms are organized on a scale larger than the convective scale, their conglomeration is called a “mesoscale convective system (MCS).” An MCS is composed of a contiguous area of precipitation that is ~100 km or greater across in at least one spatial dimension. It is apparent from radar imagery that much of the area of an MCS seen i...

The three fundamental physical laws that are used to diagnose the physical processes in severe convective storms are as follows: Newton’s equation of motion applied to a fluid (called the “Navier–Stokes equations” after their formulators or, more simply, the “equations of motion”), the first law of thermodynamics applied to a fluid, and a statement...

Mobile Doppler radar data, along with observations from a nearby Weather Surveillance Radar-1988 Doppler (WSR-88D), are assimilated with an ensemble Kalman filter (EnKF) technique into a nonhydrostatic, compressible numerical weather prediction model to analyze the evolution of the 4 May 2007 Greensburg, Kansas, tornadic supercell. The storm is sim...

Polarimetric weather radars significantly enhance the capability to infer the properties of scatterers within a resolution volume. Previous studies have identified several consistently seen polarimetric signatures in supercells observed in the central United States. Nearly all of these studies used data collected by fixed-site S- and C-band radars....

This book is a focused, comprehensive reference on recent research on severe convective storms and tornadoes. It will contain many illustrations of severe storm phenomena from mobile Doppler radars, operational Doppler radars, photographs and numerical simulations.

On 2 April 2010, a developing quasi-linear convective system (QLCS) moved rapidly northeastward through central Oklahoma spawning at least three intense, mesoscale vortices. At least two of these vortices caused damage rated as category 0 to 1 on the enhanced Fujita scale (EF0-EF1) in and near the town of Rush Springs. Two radar networks the Nation...

The second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2), which had its field phases in May and June of 2009 and 2010, was designed to explore i) the physical processes of tornadogenesis, maintenance, and demise; ii) the relationships among tornadoes, tornadic storms, and the larger-scale environment; iii) numerical weat...

On 4 May 2007, a supercell produced an EF-5 tornado that severely damaged the town of Greensburg, Kansas. Volumetric data were collected in the “Greensburg storm” by the University of Massachusetts X-band, mobile, polarimetric Doppler radar (UMass X-Pol) for 70 min; 10 tornadoes were detected. This mobile Doppler radar dataset is one of only a few...

On May 10 a very strong, cyclic supercell formed in central Oklahoma and moved across eastern Oklahoma to the Arkansas border. Along the way it produced 20 different tornadoes associated with at least 11 different mesocylones during a 4-hour period. A portion of the VORTEX2 armada intercepted the storm in east-central Oklahoma, capturing data on th...

During year 2 of VORTEX2 the University of Oklahoma, in collaboration with the University of Massachusetts and the Naval Postgraduate School, fielded three different types of mobile Doppler radars and a pulsed Doppler lidar. The U. Mass. X-Pol radar collected volumetric, polarimetric data in supercells and was paired with other VORTEX2 X-band radar...

Kelvin-Helmholtz waves were observed by the Twin Lakes, Oklahoma (KTLX), Weather Surveillance Radar-1988 Doppler (WSR-88D); the Norman, Oklahoma (KOUN), polarimetric WSR-88D; and the polarimetric Collaborative Adaptive Sensing of the Atmosphere (CASA) radars on 30 November 2006 during a winter storm in central Oklahoma. The life cycle and structure...

During the spring of 2011, there were a record number of unusually strong and devastating tornadoes in the United States, which killed more than 500 people, the most in the country since 1953. Tornadoes are responsible for more than $1 billion annually (adjusted to 2007 U.S. dollars) in property damage and for disrupting thousands of lives and busi...

A tornado outbreak occurred in central Oklahoma on 10 May 2010, including two tornadoes with enhanced Fujita scale ratings of 4 (EF-4). Tragically, three deaths were reported along with significant property damage. Several strong and violent tornadoes occurred near Norman, Oklahoma, which is a major hub for severe storms research and is arguably on...

Over the past several years, UMass has developed and deployed two mobile Doppler radars for severe storm research. One is a W-band (95 GHz) Doppler radar that is used for fine-scale observations of tornadic features. It features a very narrow (0.18°) beamwidth. The other is a dual-polarized X-band Doppler radar used for coarser scale observations a...

X-band and shorter radar wavelengths are preferable for mobile radar systems because a narrow beam can be realized with a moderately sized antenna. However, attenuation by precipitation becomes progressively more severe with decreasing radar wavelength. As a result, X band has become a popular choice for meteorological radar systems that balances t...

A mobile X-band, phased-array Doppler radar was acquired from the U.S. Army by the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) at the Naval Postgraduate School and adapted for meteorological use by ProSensing, Inc. The radar was used during field experiments conducted in the Southern Plains by faculty and students from t...

During the evening of 4May 2007, a large, powerful tornado devastated Greensburg, Kansas. The synoptic and mesoscale environments of the parent supercell that spawned this and other tornadoes are described from operational data. The formation and early evolution of this long-track supercell, within the context of its larger-scale environment, are d...

On 16 May 2003, two ground-based, mobile, Doppler radars scanned a potentially tornadic supercell in the Texas Panhandle intermittently from similar to 0200 to 0330 UTC. The storm likely was tornadic, but because it was dark, visual confirmation of any tornadoes was not possible. A damage survey was completed after the storm moved through the area....

On 15 May 2003, two ground-based, mobile, Doppler radars scanned a supercell that moved through the Texas Panhandle and cyclically produced mesocyclones. The two radars collected data from the storm during a rapid cyclic mesocyclogenesis stage and a more slowly evolving tornadic period. A 3-cm-wavelength radar scanned the supercell continuously for...

Downslope windstorms are of major concern to those living near the Boulder, Colorado area, often striking with little warning, bringing clear air wind gusts of 35-50 m/s or higher, and producing widespread damage across the city. Models used for forecasting these dangerous events are often not accurate. Hence, there is a need to apply different lin...

The nature of the different types of surface boundaries that appear in the southern plains of the United States during the convectively active season is reviewed. The following boundaries are discussed: fronts, the dryline, troughs, and outflow boundaries. The boundaries are related to their environment and to local topography. The role these bound...

A case study of a double dryline on 22 May 2002 is presented. Mobile, 3-mm-wavelength Doppler radars from the University of Massachusetts and the University of Wyoming (Wyoming cloud radar) were used to collect very fine resolution vertical-velocity data in the vicinity of each of the moisture gradients associated with the drylines. Very narrow (50...

Photographic and mobile-radar documentation of the dissipation of a supercell and a severe convective storm that had not yet developed into a mature supercell are discussed. It is hypothesized, based on these cases and on others, that when a low-precipitation or classic supercell and/or a developing supercell moves into an environment of cooler sur...

This brief case study describes the unusually benign environment in which a funnel cloud formed along a line of convective towers during the summer in Kansas. The parent cloud line was solitary and very narrow, yet organized on the mesoscale. The cloud line appeared to be best correlated with a zone of horizontal temperature gradient to the northwe...

This article is a review of the basic dynamics of severe convective storms. The dynamics are in most instances described with the aid of the vorticity and divergence equations subject to the Boussinesq approximation. The behaviour of ordinary-cell convective storms in the presence of different amounts of vertical shear and its relation to the surfa...

A variational procedure is developed that utilizes mobile ground-based range–height indicator (RHI) Doppler radar velocity data for the synthesis of two-dimensional, RHI plane wind vectors. The radial component winds are obtained with the radar platform in motion, a data collection strategy referred to as the rolling RHI technique. Using the assump...

A mobile, dual-polarization, X-band, Doppler radar scanned tornadoes at close range in supercells on 12 and 29 May 2004 in Kansas and Oklahoma, respectively. In the former tornadoes, a visible circular debris ring detected as circular regions of low values of differential reflectivity and the cross-correlation coefficient was distinguished from sur...

On 15 May 1999, a storm intercept team from the University of Oklahoma collected high-resolution, W-band Doppler radar data in a tornado near Stockton, Kansas. Thirty-five sector scans were obtained over a period of approximately 10 min, capturing the tornado life cycle from just after tornadogenesis to the decay stage. A low-reflectivity "eye"-who...

The University of Massachusetts W- and X-band, mobile, Doppler radars scanned several tornadoes at close range in south-central Kansas on 12 May 2004. The detailed vertical structure of the Doppler wind and radar reflectivity fields of one of the tornadoes is described with the aid of boresighted video. The inside wall of a weak-echo hole inside th...

During the spring seasons of 2003 and 2004, an infrared thermal camera was deployed in and around supercell thunderstorms in an attempt to retrieve the temperature at the cloud base of a mesocyclone prior to tornadogenesis. The motivation for this exercise was to obtain temperature information that might indicate the thermal structure, timing, and...

The dryline has long been associated with the development of severe thunderstorms in the southern plains during the spring and early summer months. The propagation and structure of the dryline are closely tied to surface processes that are neither well understood nor well resolved with current observational capabilities. As a result, there are ofte...

In this brief contribution, photographic documentation is provided of a variety of small, tubular-shaped clouds and of a small funnel cloud pendant from a convective cloud that appears to have been modified by flow over high-altitude mountains in northeast Colorado. These funnel clouds are contrasted with others that have been documented, including...

During spring 2001 in the Southern Plains, a recurring, hitherto undocumented reflectivity signature that the authors have called the “Owl Horn” signature (because the radar reflectivity pattern resembles the profile of the Great Horned Owl) was observed on a mobile, X-band radar display. The reflectivity signature was always located at the rear si...

A ground-based, mobile, W-band Doppler-radar has been used in the U.S. during the last decade to obtain high-spatial resolution maps of the radar reflectivity and wind fields in tornadoes and dust devils. This radar is one of the best tools available for studying the substructure of intense, small-scale vortices in the boundary layer. The most sign...

In May 2003 there was a very destructive extended outbreak of tornadoes across the central and eastern United States. More than a dozen tornadoes struck each day from 3 May to 11 May 2003. This outbreak caused 41 fatalities, 642 injuries, and approximately $829 million dollars of property damage. The outbreak set a record for most tornadoes ever re...