Urban flood, including flooding from the sea, rivers and directly from rainfall that exceeds drainage capacity, and including rain-induced landslides; with particular emphasis on flood impacts in the growing megacities of the developing world, especially those situated in the tropics and subtropics. Flooding is the most common cause of disasters in the world today. Since most of the world’s major cities lie either on the coast or on a major river, the problem is set to increase as cities grow, sea level rises, and the hydrological cycle becomes more intense in a warming atmosphere. Management of floods varies according to their scale and source. For large river floods with large forecast lead times, river controls can be used to either make space for the water or to retain it upstream of vulnerable populations. For coastal floods with large lead times, evacuation may be most appropriate. For flash floods and surface water flooding, local protection and movement of people requires more precise forecasts at much shorter lead times.

Wildfire: emphasizing requirements associated with fire fighting and fire management as well as prediction of fire risk. Increasing use of wilderness areas for recreation and the spread of human settlement into forested areas are both increasing the risk from this hazard. Fire is associated with drought and high temperatures, so there will be opportunities for linking with the Sub-seasonal-To-Seasonal project in extended range prediction of these conditions. However, management of live fires also requires a detailed knowledge of both the vegetation state and wind, which can only be predicted for very short periods ahead.

Localised Extreme Wind: including localised wind maxima within tropical and extratropical cyclones (e.g. sting jets), downslope windstorms, and tornadoes. Great advances have been made in the prediction of both tropical and extra-tropical cyclones over the past decade, but wind damage and disruption mostly occur in small areas, e.g. within embedded mesoscale and convective scale weather systems. Decisions on appropriate protective action depend on knowing the location, timing and intensity of these localized wind maxima.

Disruptive winter weather: including snow, ice, fog & avalanche, and focusing on transport, energy and communications impacts. While not usually the cause of disasters, this collection of hazards, with related meteorological causes and overlapping impacts, is a major source of social and economic disruption in mid- and high-latitude regions. There will be opportunities to work with the Polar Prediction Project on this hazard. 

Urban Heat Waves and Air Pollution: while extreme heat and poor air quality may occur separately, both are associated with long-lived weather patterns, both give rise to similar health responses, and major heat-related disasters tend to involve both ingredients. There will be opportunities to work with the Sub-seasonal-To-Seasonal project on the extended range predictability of blocking events, but the main focus will be on the spatial and temporal variability of the hazard and the influence of the urban fabric through emissions and heat fluxes from the built environment.