During the late summer and early autumn of 2011, the Catskill Mountains in south-central New York State experienced devastating flooding associated with former Hurricane Irene and former Tropical Storm Lee. Even in this particularly flood-prone region, the events of fall 2011 are perceived to be unique in the known history of the region and marked a turning point in the perceptions of residents about climate change. Here, precipitation and stream gage records are analyzed to determine just how unusual this season was. The historical precipitation gage record requires careful analysis due to the changing availability of stations. After a set of stations is developed that is appropriate for this analysis, events of lengths 1 day, 5 days, and 60 days are analyzed to identify regionally significant events (as opposed to events localized to one basin) since the early 20th century and to evaluate Irene and Lee in that historical context. Gage record results corroborate the perceptions of local residents that the period between 1996 and 2011, and in particular the events of fall 2011, were unprecedented in the last 100 years and as inferred from analyses of regional tree rings, probably in the last 500 years.
Floods in New York, 1972 with special reference to tropical storm Agnes