Event or a situation with a leadin time of days, weeks or even months (such as health pandemic, flooding, industrial action), the final impact of which may not be apparent early on (in contrast to rapid onset emergenc)
Cabinet Office, Civil Protection Lexicon: A developing single point of reference for UK Civil Protection terminology, Version 1.0, UK 2009. http://webarchive.nationalarchives.gov.uk/+/http:/ /www.cabinetoffice.gov.uk/media/230446/lexicon.pdf , (Emr Mgt - Brit) {19}