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Joseph B. Pollina, Brian A. Colle, and Joseph J. Charney

1. Introduction a. Motivation Wildfires are an important forecast problem with significant societal impacts. Across the United States, ~4.7 million (~500 000) acres burn on average each year from wildfires west (east) of the Mississippi River (NIFC 2008 ). [This is equivalent to ~1.9 million (~202 430) ha, where 1 ha = 2.47 acre.] Wildfires in the northeast United States ( Fig. 1 ) have resulted in 13 633 acres burned on average annually, which is 0.27% of the total acres burned within the

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Neil P. Lareau and Craig B. Clements

1. Introduction Smoke dispersion is strongly affected by the structure and evolution of wildfire convective plumes. When wildfire plumes penetrate into the free troposphere they inject smoke aloft, causing regional- to global-scale impacts such as reduced insolation ( Penner et al. 1992 ) and modified cloud microphysics ( Andreae et al. 2004 ). On the other hand, when plumes remain confined within the atmospheric boundary layer, the smoke can more directly impact human populations, posing

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A. Park Williams, Richard Seager, Max Berkelhammer, Alison K. Macalady, Michael A. Crimmins, Thomas W. Swetnam, Anna T. Trugman, Nikolaus Buenning, Natalia Hryniw, Nate G. McDowell, David Noone, Claudia I. Mora, and Thom Rahn

1. Introduction The southwestern United States (SW) experienced extreme drought in 2011, related at least in part to a La Niña event in the tropical Pacific Ocean ( Rupp et al. 2012 ; Hoerling et al. 2013 ; Seager et al. 2014a ). The 2011 SW drought event was accompanied by record-breaking total burned area ( Williams et al. 2014 ) and record-size “megafires” in the forests of eastern Arizona and northern New Mexico. Extreme drought and wildfire conditions prompted widespread concern as to

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Ted M. Uecker, Susan D. Kaspari, Keith N. Musselman, and S. McKenzie Skiles

increase the solar radiation absorbed by the snowpack ( Hansen and Nazarenko 2004 ; Andreae and Gelencsér 2006 ; Painter et al. 2012 ). Slight reductions in snow albedo can increase melt rates and alter the timing and magnitude of seasonal streamflow ( Hall 2004 ; Flanner et al. 2009 ; Skiles et al. 2012 ). Warming temperatures and less persistent snow cover have led to increases in wildfire frequency, magnitude, severity, and duration in the western United States ( Westerling et al. 2006

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Timothy J. Lang, Steven A. Rutledge, Brenda Dolan, Paul Krehbiel, William Rison, and Daniel T. Lindsey

1. Introduction Pyrocumulus clouds frequently occur over wildfires, often growing to high altitudes and impacting chemical composition and aerosol concentrations in the upper troposphere ( Fromm et al. 2010 ). On occasion, these clouds also have been observed to electrify and produce lightning ( Latham 1991 ; Rosenfeld et al. 2007 ). Interestingly, observed cloud-to-ground (CG) lightning flashes from these clouds, or other thunderstorms ingesting smoke, will often transfer a predominantly

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P. Grady Dixon, Gregory B. Goodrich, and William H. Cooke

many studies of climatic effects on wildfires in the southeastern United States ( Simard et al. 1985 ; Brenner 1991 ; Goodrick and Hanley 2005 ), but there is a respectable body of research literature that addresses the typical effects of those same climate patterns on the regional weather of the southeastern United States. Therefore, the purpose of this study is to merge two previously separate groups of research in order to gain a better understanding of the impacts that climate variability has

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H. F. Dacre, B. R. Crawford, A. J. Charlton-Perez, G. Lopez-Saldana, G. H. Griffiths, and J. Vicencio Veloso

This paper details the design, development, and initial testing of a prototype probabilistic wildfire warning system for Chile. Wildfires are fires that spread unchecked in forest/rural lands and rural–urban interfaces, through forests, woody shrubs, and herbaceous vegetation, living or dead ( Ubeda and Sarricolea 2016 ). They can burn from days to weeks and can lead to loss of life and property. Given the enormous damage potential, a number of warning systems have been developed to forecast

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Matthew G. Slocum, William J. Platt, Brian Beckage, Steve L. Orzell, and Wayne Taylor

1. Introduction Fire is a pivotal disturbance process influencing ecosystems over much of the world’s terrestrial surface ( Chapin et al. 2002 ). How fire does this is fundamentally linked to climate cycles. For example, in seasonal environments large natural wildfires occur during the transitions between the dry and wet seasons, with the former desiccating and connecting fuels, and the latter producing lightning ignitions ( Johnson 1992 ; Chu et al. 2002 ; Beckage et al. 2003 ; Riaño et al

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Craig B. Clements, Neil P. Lareau, David E. Kingsmill, Carrie L. Bowers, Chris P. Camacho, Richard Bagley, and Braniff Davis

Observations from within the fire environment during active wildfires highlight meteorological processes associated with fire–atmosphere interactions. Wildfires are a high-impact societal problem for the western United States and other fire-prone regions through threats to life and property, damage to natural resources, and degraded human health resulting from smoke. In addition, fire suppression costs strain federal, state, and local resources. For example, in the 1990s, the total annual fire

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Tom Rolinski, Scott B. Capps, Robert G. Fovell, Yang Cao, Brian J. D’Agostino, and Steve Vanderburg

from a wildfire potential perspective, taking into consideration both the fuel characteristics and weather. As we have found, the index discussed herein provides a robust descriptor of both Santa Ana winds and the potential for wildfire activity. Used in conjunction with a mean sea level pressure (MSLP) map type, this is a powerful method for separating Santa Ana wind events from the more typical nocturnal offshore flows that occur throughout the coastal and valley areas (i.e., land breeze) during

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