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Dive into the research topics where Kelly Lombardo is active.

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Featured researches published by Kelly Lombardo.


Journal of Climate | 2013

North American Climate in CMIP5 Experiments. Part I: Evaluation of Historical Simulations of Continental and Regional Climatology*

Justin Sheffield; Andrew P. Barrett; Brian A. Colle; D. Nelun Fernando; Rong Fu; Kerrie L. Geil; Qi Hu; J. L. Kinter; Sanjiv Kumar; Baird Langenbrunner; Kelly Lombardo; Lindsey N. Long; Eric D. Maloney; Annarita Mariotti; Joyce E. Meyerson; Kingtse C. Mo; J. David Neelin; Sumant Nigam; Zaitao Pan; Tong Ren; Alfredo Ruiz-Barradas; Yolande L. Serra; Anji Seth; Jeanne M. Thibeault; Julienne Stroeve; Ze Yang; Lei Yin

AbstractThis is the first part of a three-part paper on North American climate in phase 5 of the Coupled Model Intercomparison Project (CMIP5) that evaluates the historical simulations of continental and regional climatology with a focus on a core set of 17 models. The authors evaluate the models for a set of basic surface climate and hydrological variables and their extremes for the continent. This is supplemented by evaluations for selected regional climate processes relevant to North American climate, including cool season western Atlantic cyclones, the North American monsoon, the U.S. Great Plains low-level jet, and Arctic sea ice. In general, the multimodel ensemble mean represents the observed spatial patterns of basic climate and hydrological variables but with large variability across models and regions in the magnitude and sign of errors. No single model stands out as being particularly better or worse across all analyses, although some models consistently outperform the others for certain variab...


Journal of Climate | 2014

North American Climate in CMIP5 Experiments: Part III: Assessment of Twenty-First-Century Projections*

Eric D. Maloney; Suzana J. Camargo; Edmund K. M. Chang; Brian A. Colle; Rong Fu; Kerrie L. Geil; Qi Hu; Xianan Jiang; Nathaniel C. Johnson; Kristopher B. Karnauskas; James L. Kinter; Benjamin Kirtman; Sanjiv Kumar; Baird Langenbrunner; Kelly Lombardo; Lindsey N. Long; Annarita Mariotti; Joyce E. Meyerson; Kingtse C. Mo; J. David Neelin; Zaitao Pan; Richard Seager; Yolande L. Serra; Anji Seth; Justin Sheffield; Julienne Stroeve; Jeanne M. Thibeault; Shang-Ping Xie; Chunzai Wang; Bruce Wyman

AbstractIn part III of a three-part study on North American climate in phase 5 of the Coupled Model Intercomparison Project (CMIP5) models, the authors examine projections of twenty-first-century climate in the representative concentration pathway 8.5 (RCP8.5) emission experiments. This paper summarizes and synthesizes results from several coordinated studies by the authors. Aspects of North American climate change that are examined include changes in continental-scale temperature and the hydrologic cycle, extremes events, and storm tracks, as well as regional manifestations of these climate variables. The authors also examine changes in the eastern North Pacific and North Atlantic tropical cyclone activity and North American intraseasonal to decadal variability, including changes in teleconnections to other regions of the globe. Projected changes are generally consistent with those previously published for CMIP3, although CMIP5 model projections differ importantly from those of CMIP3 in some aspects, inc...


Journal of Climate | 2013

Historical Evaluation and Future Prediction of Eastern North American and Western Atlantic Extratropical Cyclones in the CMIP5 Models during the Cool Season

Brian A. Colle; Zhenhai Zhang; Kelly Lombardo; Edmund K. M. Chang; Ping Liu; Minghua Zhang

AbstractExtratropical cyclone track density, genesis frequency, deepening rate, and maximum intensity distributions over eastern North America and the western North Atlantic were analyzed for 15 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) for the historical period (1979–2004) and three future periods (2009–38, 2039–68, and 2069–98). The cyclones were identified using an automated tracking algorithm applied to sea level pressure every 6 h. The CMIP5 results for the historical period were evaluated using the Climate Forecast System Reanalysis (CFSR). The CMIP5 models were ranked given their track density, intensity, and overall performance for the historical period. It was found that six of the top seven CMIP5 models with the highest spatial resolution were ranked the best overall. These models had less underprediction of cyclone track density, more realistic distribution of intense cyclones along the U.S. East Coast, and more realistic cyclogenesis and deepening rates. The best...


Journal of the Atmospheric Sciences | 2007

Tropical Cyclogenesis within an Equatorial Rossby Wave Packet

John Molinari; Kelly Lombardo; David Vollaro

Abstract A packet of equatorial Rossby (ER) waves that lasted 2.5 months is identified in the lower troposphere of the northwest Pacific. Waves within the packet had a period of 22 days, a wavelength of 3600 km, a westward phase speed of 1.9 m s−1, and a near-zero group speed. The wave properties followed the ER wave dispersion relation with an equivalent depth near 25 m. The packet was associated with the development of at least 8 of the 13 tropical cyclones that formed during the period. A composite was constructed around the genesis locations. Tropical cyclones formed east of the center of the composite ER wave low in a region of strong convection and a separate 850-hPa vorticity maximum. The background flow during the life of the packet was characterized by 850-hPa zonal wind convergence and easterly vertical wind shear. Wave amplitude peaked at the west end of the convergent region, suggesting that wave accumulation played a significant role in the growth of the packet. The presence of easterly verti...


Monthly Weather Review | 2010

The Spatial and Temporal Distribution of Organized Convective Structures over the Northeast and Their Ambient Conditions

Kelly Lombardo; Brian A. Colle

Abstract Organized convective structures over the northeastern United States were classified for two warm seasons (May–August) using 2-km composite radar [i.e., the National Operational Weather Radar (NOWrad)] data. Nine structures were identified: three types of cellular convection (clusters of cells, isolated cells, and broken lines), five types of linear convection (lines with no stratiform precipitation, lines with trailing stratiform precipitation, lines with parallel stratiform precipitation, lines with leading stratiform precipitation, and bow echoes), and one nonlinear system. The occurrence of all structures decreases from the western Appalachian slopes eastward to the Atlantic coast. Isolated cellular convection forms primarily during the morning to late afternoon (1200–2100 UTC) mainly over the high terrain. Clusters of cells form primarily over the Appalachians and the Atlantic coastal plain during the daytime (1200–0000 UTC). Linear convection is favored from midafternoon to early evening (18...


Journal of Climate | 2015

Evaluation of Historical and Future Cool Season Precipitation over the Eastern United States and Western Atlantic Storm Track Using CMIP5 Models

Kelly Lombardo; Brian A. Colle; Zhenhai Zhang

AbstractThis study analyzed the contribution of cyclones to projected changes in cool season (1 November–31 March) precipitation over the eastern United States and western North Atlantic Ocean. First, global climate model simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) were compared to Global Precipitation Climatology Project (GPCP) and Climate Prediction Center (CPC) precipitation analyses for the period 1979–2004. The CMIP5 ensemble mean realistically reproduced the historical distribution of regional precipitation with no discernable effect because of model spatial resolution. Subsequently, the projected changes in precipitation on cyclone and noncyclone days under the representative concentration pathway 8.5 (RCP8.5) scenario were quantified. While precipitation on both types of days was projected to increase, the increase on noncyclone days (23%) was greater than the increase on cyclone days (12%). The increase in precipitation on cyclone days occurred despite a decrease...


Weather and Forecasting | 2011

Convective Storm Structures and Ambient Conditions Associated with Severe Weather over the Northeast United States

Kelly Lombardo; Brian A. Colle

AbstractThis study documents the convective storm structures and ambient conditions associated with severe storms (wind, hail, and tornado) over the northeastern United States for two warm seasons (May–August), including 2007 and a warm season comprising randomly selected days from 2002 to 2006. The storms were classified into three main convective organizational structures (cellular, linear, and nonlinear) as well as several subcategories. The same procedure was applied to the highly populated coastal zone of the northeastern United States, including New Jersey, Connecticut, Rhode Island, and New York. The coastal analysis included six warm seasons from 2002 to 2007. Over the Northeast, severe wind events are evenly distributed among the cellular, linear, and nonlinear structures. Cellular structures are the primary hail producers, while tornadoes develop mainly from cellular and linear structures. Over the coastal zone, primarily cellular and linear systems produce severe wind and hail, while tornadoes ...


Monthly Weather Review | 2017

Insights into the Evolving Microphysical and Kinematic Structure of Northeastern U.S. Winter Storms from Dual-Polarization Doppler Radar

Matthew R. Kumjian; Kelly Lombardo

AbstractThe recent Weather Surveillance Radar-1988 Doppler (WSR-88D) network upgrade to dual-polarization capabilities allows for bulk characterization of microphysical processes in northeastern U.S. winter storms for the first time. In this study, the quasi-vertical profile (QVP) technique (wherein data from a given elevation angle scan are azimuthally averaged and the range coordinate is converted to height) is extended and applied to polarimetric WSR-88D observations of six Northeast winter storms to survey their evolving, bulk vertical microphysical and kinematic structures. These analyses are supplemented using hourly analyses from the Rapid Refresh (RAP) model. Regions of ascent inferred from QVPs were consistently associated with notable polarimetric signatures, implying planar crystal growth when near −15°C, and riming and secondary ice production at higher temperatures. The heaviest snowfall occurred most often when ascent and enhanced propagation differential phase shift () occurred near −15°C. ...


Monthly Weather Review | 2016

Sensitivity of Simulated Sea Breezes to Initial Conditions in Complex Coastal Regions

Kelly Lombardo; Eric Sinsky; Yan Jia; Michael M. Whitney; James B. Edson

AbstractMesoscale simulations of sea breezes are sensitive to the analysis product used to initialize the simulations, primarily due to the representation of the coastline and the coastal sea surface temperatures (SSTs) in the analyses. The use of spatially coarse initial conditions, relative to the horizontal resolution of the mesoscale model grid, can introduce errors in the representation of coastal SSTs, in part due to the incorrect designation of the land surface. As a result, portions of the coastal ocean are initialized with land surface temperature values and vice versa. The diurnal variation of the sea surface is typically smaller than over land on meso- and synoptic-scale time scales. Therefore, it is common practice to retain a temporally static SST in numerical simulations, causing initial SST errors to persist through the duration of the simulation. These SST errors influence horizontal coastal temperature and humidity gradients and thereby the development of the sea-breeze circulations.The a...


Journal of Geophysical Research | 2016

Synoptic forcing of wind relaxations at Pt. Conception, California

Melanie R. Fewings; Libe Washburn; Clive E. Dorman; Christopher Gotschalk; Kelly Lombardo

Over the California Current upwelling system in summer, the prevailing upwelling-favorable winds episodically weaken (relax) or reverse direction for a few days. Near Pt. Conception, California, the wind usually does not reverse, but wind relaxation allows poleward oceanic coastal flow with ecological consequences. To determine the offshore extent and synoptic forcing of these wind relaxations, we formed composite averages of wind stress from the QuikSCAT satellite and atmospheric pressure from the North American Regional Reanalysis (NARR) using 67 wind relaxations during summer 2000–2009. Wind relaxations at Pt. Conception are the third stage of an event sequence that repeatedly affects the west coast of North America in summer. First, 5–7 days before the wind weakens near Pt. Conception, the wind weakens or reverses off Oregon and northern California. Second, the upwelling-favorable wind intensifies along central California. Third, the wind relaxes at Pt. Conception, and the area of weakened winds extends poleward to northern California over 3–5 days. The NARR underestimates the wind stress within 200 km of coastal capes by a factor of 2. Wind relaxations at Pt. Conception are caused by offshore extension of the desert heat low. This synoptic forcing is related to event cycles that cause wind reversal as in Halliwell and Allen (1987) and Mass and Bond (1996), but includes weaker events. The wind relaxations extend 600 km offshore, similarly to the California-scale hydraulic expansion fan shaping the prevailing winds, and 1000 km alongshore, limited by an opposing pressure gradient force at Cape Mendocino.

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Anji Seth

University of Connecticut

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Annarita Mariotti

National Oceanic and Atmospheric Administration

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Eric D. Maloney

Colorado State University

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Eric Sinsky

National Oceanic and Atmospheric Administration

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