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Forecasting and early warning systems are important investments to protect lives, properties, and livelihood. While early warning systems are frequently used to predict the magnitude, location, and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services, or financial loss. Complementing early warning systems with impact forecasts has a twofold advantage: It would provide decision makers with richer information to take informed decisions about emergency measures and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multihazard early warning systems. This review discusses the state of the art in impact forecasting for a wide range of natural hazards. We outline the added value of impact‐based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe. Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While such systems are frequently used to predict the magnitude, location, and timing of potentially damaging events, they rarely provide impact estimates, such as the expected physical damage, human consequences, disruption of services, or financial loss. Extending hazard forecast systems to include impact estimates promises many benefits for the emergency phase, for instance, for organizing evacuations. We review and compare the state of the art of impact forecasting across a wide range of natural hazards and outline opportunities and key challenges for research and development of impact forecasting. Probabilistic forecasts and rapid estimates of event impacts offer new possibilities for coping with damaging events in the emergency phaseDeveloping impact forecasting that includes exposure and vulnerability estimates will tap into synergies across disciplinesExtending single‐hazard to multihazard impact forecasts considering interactions between hazards and vulnerabilities is the next challenge

The processes leading to the development of hail and the distribution of these events worldwide are reviewed. Microphysical and physical characteristics of hail development are described to provide context of the notable gaps in our understanding of what drives hail to grow large, or what determines how it falls to the ground. Distributional characteristics of hail are explored, utilizing both surface observations of hailstones and remotely sensed observational data sets to identify opportunities and needs for new observations. These observational deficiencies contribute to our limited capacity to both forecast hail or its expected size and reduce the effectiveness of using favorable conditions for hail development as a proxy to frequency where observations are unavailable. Given the substantive influences of both climate variability and the changing Earth system on hail, the latest understanding of their contributions to risk are addressed. Applying this understanding of the distribution and physical characteristics of hail, the damage by hail to agriculture and insured property is assessed. Much remains unknown about the processes leading to hail growth and environmental controls on hail occurrence, size, and magnitude, particularly outside of the United States and Europe. A better understanding of the global occurrence of hail is also needed to better anticipate the hazard and associated impacts. The processes leading to the development of hail and the resulting distribution of these events worldwide are reviewed. Hail forms from small frozen embryos that are lofted into the updraft of a thunderstorm, subsequently encountering a region of supercooled water, and growing by either riming or accumulation. Contrary to popular belief, the suggestion that hailstones that take multiple up‐and‐down excursions through an updraft are not observed. Hail can grow to large sizes on any continent, and stones as large as 200 mm have been recorded. Damages associated with hail reach more than 10 billion U.S. dollars a year in North America alone. In this review a range of topics are covered, including characteristics of hail growth and development, surface observations of hail, remotely sensed observations, the approaches to forecasting hail and estimating its frequency where observations are unavailable, the influences of climate variability and a warming earth system and the impacts on insured property. Much remains unknown about the processes leading to hail growth and environmental controls on hail occurrence, size, and magnitude, particularly outside of the United States and Europe. A better understanding of the global occurrence of hail is also needed to better anticipate the hazard and associated impacts. Global hail research is reviewed, encompassing formation, occurrence, and impactsMuch remains unknown about the growth processes and environmental controlsImproved understanding of hail occurrence is needed to better anticipate the hazard

The analyses specific threshold of lightning discharges density and thunderstorms days for different type of landscape and level of altitudes were determinate. For Central Europe from 9deg W to 20deg E and from 42deg to 56deg N (11deg x 14deg sectors) for April-September period from 2001 to 2014 were investigated. For Europe for the altitude range from 10 m below sea level (bsl) to 200 m above sea level (asl) the highest lightning discharge density is associated with the forest, shrub and wet, urban areas. For the altitude range 200-1000 m asl the highest lightning discharges density is associated with water (river, lakes), urban and forest areas. For the altitude range level from 1000 m asl to 2000 m asl the highest lightning discharges density is associated with the water, forest and grass types. A dense forest on the track of the flow of a moist air mass can promote the rise of air and the formation of convective clouds and lightning strokes. The effect of rives, channels and large lakes on moisture and development of thunderstorm clouds may account for impact on cloud-to-ground (CG) lightning activity. For three flat 3deg x 5deg areas with similar meteorological and synoptic conditions, increased CG lightning activity is possible if there is a difference in altitude between different types of landscapes. The altitude difference further contributes to the development of convective clouds producing lightning.