Extreme Weather Event (EWE)

A subset of "Hazard" and "Threat" to CI comprise Extreme Weather Events (EWE) which causes a CI disruption or, even more often, a Common Cause Failure of multiple CI.

EWE comprise:

1. long duration drought
2. extreme precipitation in a short period of time (e.g., flash floods, water bombs)
3. (extreme) cold wave / cold snaps / ice & snow storms
4. (extreme) heat wave
5. extreme wind (hurricanes, tornadoes, Derecho, etc.)

Definitions

EU definitions

CLIMATE-ADAPT

An extreme weather event is an event that is rare at a particular place and time of year.

Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of the observed probability density function. By definition, the characteristics of what is called extreme weather may vary from place to place in an absolute sense. Single extreme events cannot be simply and directly attributed to anthropogenic climate change, as there is always a finite chance the event in question might have occurred naturally. When a pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total that is itself extreme (e.g. drought or heavy rainfall over a season).

International Definitions

IPCC

An extreme weather event (EWE) is an event that is rare at a particular place and time of year.

Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10^th or 90^th percentile of a probability density function estimated from observations.

National Definitions

Australia

An extreme weather event is an event that is rare at a particular place and time of year.

Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of a probability density function estimated from observations.
Moreover, Australia has defined severe weather:

Severe weather is any atmospheric condition potentially destructive or hazardous to human beings.

Severe weather is often associated with extreme convective weather (tropical cyclones, tornadoes, severe thunderstorms, squalls, etc.) and with storms of freezing precipitation or blizzard conditions.

Denmark

Det er ekstremvejr, når vejret er sjældent på det specifikke sted eller tidspunkt.

Ekstremvejr vil normalt forekomme sjældent, og definitionen af ekstremvejr vil variere fra sted til sted. Enkeltforekommende hændelser af ekstremvejr kan ikke tilskrives menneskeskabt klimaforandring, da den enkelte, konkrete hændelse også kan være udtryk for naturlig variation i vejret. Når der i et længere tidsinterval som for eksempel en sæson har forekommet et nyt mønster af ekstremvejr, kan det klassificeres som et ekstremt klimafænomen, især hvis det giver en middelværdi eller total, der i sig selv er ekstrem for eksempel tørke eller kraftig regn i en hel sæson.

Germany

Extreme weather event (or extreme event) is any weather situation that occurs extremely rarely at a given place at this time of year is an extreme weather event.

If extreme weather persists for a long period of time, it may be classified as an “extreme climate event”.

Extremes Wetterereignis, Extremereignis: Ein extremes Wetterereignis ist ein Ereignis, das an einem bestimmten Ort und zu einer bestimmten Jahreszeit selten ist.

Die Definitionen für “selten” variieren, aber ein extremes Wetterereignis wäre normalerweise so selten wie oder seltener als das 10- oder 90%-Perzentil der beobachteten Wahrscheinlichkeitsverteilung. Per Definition kann die Charakteristik von so genanntem “Extremwetter” absolut gesehen von Ort zu Ort unterschiedlich sein. Einzelne Extremereignisse können nicht einfach und direkt der anthropogenen Klimaänderung zugeordnet werden, da immer eine begrenzte Chance besteht, dass das betreffende Ereignis natürlicherweise hätte auftreten können. Wenn ein Muster von extremem Wetter über eine bestimmte Zeitspanne, z. B. eine Saison, bestehen bleibt, kann es als “extremes Klimaereignis” klassiert werden, vor allem wenn es ein Mittel bzw. eine Summe aufweist, die seinerseits bzw. ihrerseits extrem ist (z. B. eine Dürre oder Starkniederschlag während einer ganzen Saison).

India

Extreme weather conditions: க2ைமயான வானிைல

(States of) Jersey

Extreme weather event: an event that is rare at a particular place and time of year.

By definition, the characteristics of what is called extreme weather may vary from place to place. When a pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total that is itself extreme (e.g. drought or heavy rainfall over a season).

Kiribati

Angibuaka aika aki bati n roroko n taabo n tabeua n taai ao n ririki aika a bati n aron te angibuaka ae korakora,te mwautakataka ao te nao ae kabuebue.

Extreme (weather) event: Weather conditions that are rare for a particular place and/or time of year eg an intense storm, drought, heat wave, severe storms.

Netherlands

Onder 'extreem weer' verstaan wij alle meteorologische verschijnselen die voor Nederlandse begrippen uitzonderlijk hevig zijn.

United Kingdom (UK)

Extreme weather includes unusual, severe or unseasonal weather; or weather at the extremes of the range of weather seen in the past.

United States

NOAA

The U.S. National Oceanic and Atmospheric Administration (NOAA) uses a definition of extreme weather based on an event's climatologically-expected distribution. An event is called extreme if occurs, for example, only five per cent or less of the time. NOAA notes, however, that the exact choice of cut-off of the climatologically probability value used in the definition is somewhat arbitrary. A simple example of extreme weather is therefore when the temperature drops to a level which occurs less than five per cent of the time, say below -20 C. Extreme events, by definition, are rare.

See also

• Hydrometeorological Hazard
• Natural Hazard