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Monday morning in Boulder officially put the city over its all-time annual precipitation record
After nine consecutive days with rain, skies have finally cleared over flood-ravaged Boulder, Colorado. Flooding from the past week's rains have killed at least seven, destroyed over 1,500 homes, damaged 18,000 homes, and caused close to $1 billion in damage, according to insurance broker Aon Benfield. Over 70 bridges have been damaged or destroyed, and hundreds of roads damaged, including major sections of U.S. Highways 34, 36 and 72. Clear skies are forecast for the remainder of the week, which will allow rescue helicopters to safely operate to evacuate the hundreds of people still trapped in mountain towns cut off by the rockslides, collapsed bridges, and destroyed roads. The rains that fell early Monday morning in Boulder officially put the city over its all-time annual precipitation record with three and a half months left in the year. Boulder has been deluged with 30.13" so far this year; the previous record was 29.93", set in 1995.
A 1-in-1,000 year flood and rainfall event
The Colorado Emergency Management Agency reported that “Some areas in Larimer County experienced a 100-year flood and other areas experienced a 1,000-year flood. It all depends on where the heaviest rain fell. Areas with more extensive damage experienced the 1,000 year flooding.” The U.S. Geological Survey office in Colorado called the flood of Boulder Creek in the city of Boulder as at least a 1-in-100-year event. In the towns of Lyons and Estes Park, officials separately described the current event in each area as a 1-in-500-year flood. According to Bob Henson of the National Center for Atmospheric Research in Boulder, 17.16" of rain fell in the past week in Boulder. Using about a century of precipitation records, NOAA has constructed a Precipitation Frequency Data Server, which estimates how often we might expect to see extreme rainfall events recur. For Boulder, a 5.87" rain event in one week has an average recurrence interval of once every 1,000 years. The city received almost triple that amount of rain over the past week--a truly extreme and rare weather event.
As extreme as the 2013 Colorado flood was, there are two flood events in Colorado history that compare. One was the June 1965 flood that hit the Colorado Front Range, causing $4 billion in damage (adjusted for inflation.) Colorado's deadliest flood on record was the Big Thompson Flood of 1976, which killed 145 people between Estes Park and Loveland. More than 12" of rain fell in just three hours, causing a flood rated at between a 500-year and 1,000-year event.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2525
A 1-in-1,000 year flood and rainfall event
The Colorado Emergency Management Agency reported that “Some areas in Larimer County experienced a 100-year flood and other areas experienced a 1,000-year flood. It all depends on where the heaviest rain fell. Areas with more extensive damage experienced the 1,000 year flooding.” The U.S. Geological Survey office in Colorado called the flood of Boulder Creek in the city of Boulder as at least a 1-in-100-year event. In the towns of Lyons and Estes Park, officials separately described the current event in each area as a 1-in-500-year flood. According to Bob Henson of the National Center for Atmospheric Research in Boulder, 17.16" of rain fell in the past week in Boulder. Using about a century of precipitation records, NOAA has constructed a Precipitation Frequency Data Server, which estimates how often we might expect to see extreme rainfall events recur. For Boulder, a 5.87" rain event in one week has an average recurrence interval of once every 1,000 years. The city received almost triple that amount of rain over the past week--a truly extreme and rare weather event.
As extreme as the 2013 Colorado flood was, there are two flood events in Colorado history that compare. One was the June 1965 flood that hit the Colorado Front Range, causing $4 billion in damage (adjusted for inflation.) Colorado's deadliest flood on record was the Big Thompson Flood of 1976, which killed 145 people between Estes Park and Loveland. More than 12" of rain fell in just three hours, causing a flood rated at between a 500-year and 1,000-year event.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2525