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2013 Colorado floods
The 2013 Colorado floods were a series of natural disasters occurring in the U.S. state of Colorado. Starting on September 11, 2013, a slow-moving cold front stalled over Colorado, clashing with warm humid monsoonal air from the south. This resulted in heavy rain and catastrophic flooding along Colorado's Front Range from Colorado Springs north to Fort Collins. The situation intensified on September 11 and 12. Boulder County was worst hit, with 9.08 inches (231 mm) recorded September 12 and up to 18 inches (460 mm) of rain recorded by September 15, which is comparable to Boulder County's average annual precipitation (20.7 inches, 525 mm). This event has also been referred to as the 2013 Colorado Front Range Flood, reflecting a more precise geographic extent in and along the Colorado Front Range mountains.
The National Weather Service's Hydrometeorological Design Studies Center stated in a document that the annual exceedance probability (AEP) for the entire rainfall event was as low as 1/1000 (0.1%) in places.
The flood waters spread across a range of almost 200 miles (320 km) from north to south, affecting 17 counties. Governor John Hickenlooper declared a disaster emergency on September 12, 2013, in 14 counties: Adams, Arapahoe, Broomfield, Boulder, Denver, El Paso, Fremont, Jefferson, Larimer, Logan, Morgan, Pueblo, Washington and Weld. By September 15, federal emergency declarations covered those 14 counties as well as Clear Creek County.
The state of Colorado had been experiencing varying levels of drought prior to the week of storms starting on September 9. The U.S. Drought Monitor stated that "The combination of ample Gulf and Pacific tropical moisture (in part from Tropical Storms Manuel (Pacific) and Ingrid (Gulf) which inundated Mexico), stalled frontal systems, and upsloping conditions produced the widespread rainfall [along Colorado's Front Range]." This resulted in rainfall totals exceeding 20 inches in parts of Boulder County, along with numerous flash floods, property destruction and loss of life.
Colorado has a semi-arid climate and a history of flash flooding. The earliest recorded flood in Boulder was the great flood of 1894 which came down Boulder Canyon and flooded most of the downtown area. In 1965 another flood hit Colorado.[citation needed]
The Big Thompson River begins around Estes Park in northern Colorado and flows east into Big Thompson Canyon. On July 31, 1976, the Big Thompson Flood of 1976 struck. 8 inches of rainfall fell in the first hour alone; 12 inches fell in the first three hours. The flash flooding killed 144 people and caused $35 million worth of damage, or roughly $140 million in 2013.
Comparatively, the 2013 flood was caused by approximately 15 inches of rainfall over the span of a week, killed 8 people, and caused $2 billion in damage. The rainfall in 2013 exceeded that of the 1976 event, but the flooding was more intense in 1976 because the rainfall that fell occurred in a much shorter time frame. To illustrate this: in 2013, The Big Thompson River experienced peak flow rates near Loveland, CO of 4,500 CFS (127.43 cubic meters per second) before the measuring gauge was destroyed by floodwaters, whereas, in 1976, the same area of the river saw peak flow rates of 31,200 cubic feet per second (880 cubic meters per second).
At least eight deaths were reported by the Colorado Office of Emergency Management, with two more missing and presumed dead and hundreds remaining unaccounted for. More than 11,000 were evacuated. The town of Lyons in Boulder County was isolated by the flooding of St. Vrain Creek, and several earth dams along the Front Range burst or were over-topped. On September 12, Boulder Creek was reported to have exceeded 5,000 cubic feet (140 m3) of water per second. Boulder Creek regularly flows around 150–200 cubic feet (4.2–5.7 m3) per second. This caused serious damage to buildings along the creek and the creek path such as Boulder High School. As of late September 13, according to the Office of Emergency Management, there were 172 people unaccounted for and at least three dead in flood areas of Boulder County. By September 14, the death toll had reached five and more than 500 were unaccounted for, but not necessarily considered missing.
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2013 Colorado floods
The 2013 Colorado floods were a series of natural disasters occurring in the U.S. state of Colorado. Starting on September 11, 2013, a slow-moving cold front stalled over Colorado, clashing with warm humid monsoonal air from the south. This resulted in heavy rain and catastrophic flooding along Colorado's Front Range from Colorado Springs north to Fort Collins. The situation intensified on September 11 and 12. Boulder County was worst hit, with 9.08 inches (231 mm) recorded September 12 and up to 18 inches (460 mm) of rain recorded by September 15, which is comparable to Boulder County's average annual precipitation (20.7 inches, 525 mm). This event has also been referred to as the 2013 Colorado Front Range Flood, reflecting a more precise geographic extent in and along the Colorado Front Range mountains.
The National Weather Service's Hydrometeorological Design Studies Center stated in a document that the annual exceedance probability (AEP) for the entire rainfall event was as low as 1/1000 (0.1%) in places.
The flood waters spread across a range of almost 200 miles (320 km) from north to south, affecting 17 counties. Governor John Hickenlooper declared a disaster emergency on September 12, 2013, in 14 counties: Adams, Arapahoe, Broomfield, Boulder, Denver, El Paso, Fremont, Jefferson, Larimer, Logan, Morgan, Pueblo, Washington and Weld. By September 15, federal emergency declarations covered those 14 counties as well as Clear Creek County.
The state of Colorado had been experiencing varying levels of drought prior to the week of storms starting on September 9. The U.S. Drought Monitor stated that "The combination of ample Gulf and Pacific tropical moisture (in part from Tropical Storms Manuel (Pacific) and Ingrid (Gulf) which inundated Mexico), stalled frontal systems, and upsloping conditions produced the widespread rainfall [along Colorado's Front Range]." This resulted in rainfall totals exceeding 20 inches in parts of Boulder County, along with numerous flash floods, property destruction and loss of life.
Colorado has a semi-arid climate and a history of flash flooding. The earliest recorded flood in Boulder was the great flood of 1894 which came down Boulder Canyon and flooded most of the downtown area. In 1965 another flood hit Colorado.[citation needed]
The Big Thompson River begins around Estes Park in northern Colorado and flows east into Big Thompson Canyon. On July 31, 1976, the Big Thompson Flood of 1976 struck. 8 inches of rainfall fell in the first hour alone; 12 inches fell in the first three hours. The flash flooding killed 144 people and caused $35 million worth of damage, or roughly $140 million in 2013.
Comparatively, the 2013 flood was caused by approximately 15 inches of rainfall over the span of a week, killed 8 people, and caused $2 billion in damage. The rainfall in 2013 exceeded that of the 1976 event, but the flooding was more intense in 1976 because the rainfall that fell occurred in a much shorter time frame. To illustrate this: in 2013, The Big Thompson River experienced peak flow rates near Loveland, CO of 4,500 CFS (127.43 cubic meters per second) before the measuring gauge was destroyed by floodwaters, whereas, in 1976, the same area of the river saw peak flow rates of 31,200 cubic feet per second (880 cubic meters per second).
At least eight deaths were reported by the Colorado Office of Emergency Management, with two more missing and presumed dead and hundreds remaining unaccounted for. More than 11,000 were evacuated. The town of Lyons in Boulder County was isolated by the flooding of St. Vrain Creek, and several earth dams along the Front Range burst or were over-topped. On September 12, Boulder Creek was reported to have exceeded 5,000 cubic feet (140 m3) of water per second. Boulder Creek regularly flows around 150–200 cubic feet (4.2–5.7 m3) per second. This caused serious damage to buildings along the creek and the creek path such as Boulder High School. As of late September 13, according to the Office of Emergency Management, there were 172 people unaccounted for and at least three dead in flood areas of Boulder County. By September 14, the death toll had reached five and more than 500 were unaccounted for, but not necessarily considered missing.