High Water

Colorado Floods, 2013


September 2013 brought catastrophic flooding to Colorado, taking lives and changing landscapes in what will almost certainly become one of the state’s costliest disasters in history. Many communities along the Front Range experienced 100 year and even 1000 year flooding, which means that in any given year there is only a 1% or 0.1% chance for such an event to occur respectively.

September 2013 was Colorado's wettest month on record, an incredible 2.7" above average statewide. Most of the precipitation that fell occurred over an eight day stretch from September 9, 2013 to September 16, 2013 across northeast Colorado and the Front Range.

In a region accustomed to 300 days of sunshine each year, the semi-arid climate of Colorado's Front Range rarely sees consecutive days of rain in a given year. The monsoonal flow that feeds Colorado’s short-lived but powerful summer thunderstorms normally comes to an end in late August. In 2013, the monsoons continued well into the month of September.

During Colorado’s eight days of rain the canyons near Boulder turned into deadly traps, the town of Lyons became severed from the rest of the state, and unprecedented amounts of water surged toward the eastern plains.

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Boulder, Colorado

“Precipitation for September 2013 was 936% of the monthly normal”

Boulder was hit particularly hard during this period of precipitation. CoCoRaHS storm reports ranged from 12" to 21" across the Front Range foothills of Boulder County, an amount equivalent to -- even exceeding -- that of a major tropical cyclone, or nearly that of an entire year's worth of precipitation for the region.

Boulder received
17.24" of precipitation
in EIGHT days, or
85% of
annual average

According to official weather observations taken at KBDU, 3.19 inches of rain had already fallen in Boulder by Wednesday night, eclipsing the city’s monthly average rainfall of 1.84 inches in just three days. Then came Thursday, where three times that amount of rain fell in a 24 hour period. Officially Boulder would record 85% of the city’s yearly average from this event, but many locations in the immediate surroundings would break their yearly averages, receiving greater than 20 inches of rain in eight days.

Daily Totals: Boulder, CO.

40.0176° N, 105.2797° W

Thursday proved to be the height of the storm for Boulder County. After days of rain, the soil was completely saturated, but the rain did not let up. The canyons west of the city became collection basins for Mother Nature's wrath. Shortly after 11pm Thursday, September 12, a new round of flood warnings were issued for the Boulder area. The eerie flood warnings wailed through the night as exhausted residents were once again warned to seek higher ground.

Stream gauges in the canyon were indicating record surges. Several signals miles up the pitch-black canyons west of town were lost as they were overtaken by water. The National Weather Service took to social media to warn.

Torrents of water washed through the streets of Boulder, while local media tried to grapple with the magnitude of the situation.


Homes and roads were destroyed in Clear Creek canyon as the river carved new landscapes through the dark of night. The extent of the damage would not be known until morning, and even then not comprehended for days.

Lyons, Colorado

“A town cut off”

Twenty miles north of Boulder is the small town of Lyons. All roads in and out of Lyons had become impassable by midweek. There are just three ways into Lyons: U.S. 36 from the south and the west, and St Vrain Drive from the southwest. The town, with a population of just over 2,000, became a top priority for the National Guard as roads turned to rivers and bridges were swept away.

Located at the foot of the Rocky Mountains, Lyons proved exceptionally vulnerable for such an historic event. The St. Vrain River, like all rivers exiting the northern Rockies east of the Continental Divide, is a tributary of the South Platte River. It was the confluence of the South and North St. Vrain creeks that proved to overwhelm the infrastructure in Lyons. The creeks and gullies that ordinarily meander through the canyons adjacent to the town turned into raging rivers.

Estes Park

“The measurement of disaster”

The town of Estes Park, a popular tourist destination for both local and international vacation seekers, serves as headquarters for Rocky Mountain National Park. Business in downtown Estes Park relies heavily on the nearly three million yearly visitors to the nearby National Park. Until the floods of September 2013, The Big Thompson flood of 1976 was long the measurement of disaster for both this small mountain community and the entire state of Colorado.

“The Big Thompson flood in 1976 remains the deadliest flash flood in Colorado history, and brought unprecedented destruction to the town.”

September 2013 brought back more than just memories for the quaint mountain town, as flash flooding enveloped homes and businesses once more. Adding to the loss, the town was inaccessible for nearly a week after the rain stopped falling -- this during one of the town's busiest months for tourism as the famous Colorado fall foliage was just beginning to change. Nearly six weeks after the floods washed out U.S. 36, the main route into town from Denver, the road still wasn’t expected to reopen until November first.

Eastern Plains

“All that water has to go somewhere”

Flooding would take its time making it to the eastern plains of Colorado. In relative terms, many communities east of Interstate 25 did not receive much actual rainfall, but would not be spared the flooding. The immense amount of water that could no longer be absorbed by the earth to the west was slowly pushing east in a methodical fashion.

From Colorado, all water east of the Great Continental Divide eventually finds it’s way to the Atlantic Ocean, and water on the west to the Pacific. The route out of northeast Colorado follows the Platte River. All the rivers and creeks responsible for the destruction in and along the Front Range foothills serve as tributaries to the Platte.

Over the course of the week following the flash flooding in the foothill communities, cities along the Platte were forced to evacuate homes within the floodplain of the river in anticipation of rising waters. Weld County was particularly hard hit. Hundreds of residents were stranded by rising waters and farmland saw devastating damage.

Post Deluge

“A flood of biblical proportion” - NWS Boulder

In the days and weeks that followed the flooding came a rush of post analysis from meteorologists around the country. The National Weather Service compiled a number of different visualizations ranging from precipitation totals maps to archived modeling. The array of images above show 24 hour rainfall totals as depicted by radar, while the animations below show a cumulative depiction of rainfall over the eight days.

Meteorologically speaking, this event was extraordinary. It took a combination of all the wrong ingredients to make it happen. A remarkably strong late season monsoonal flow pushing deep moisture up from the Gulf of Mexico, colliding with a stalled out frontal boundary providing energy and lift from the north, led to the prolonged period of heavy rain for the state. From space, the scene was truly stunning.

Nearly seven weeks since the floods struck, life is far from returning to normal. While access has been restored to many locations severed from neighboring communities, many road closures remain in place.

As the first snows of the season set in, the slow return to normalcy is aided by the opening of some of Colorado’s most treasured parks. Mountain explorers can soon travel along U.S. 36 from Boulder through to Estes Park as The Colorado Department of Transportation plans to reopen the main artery during the first week of November. And while many of the locations will only be open in a limited capacity, it is these small steps that prove some of the biggest leaps forward in the rebuilding and healing process.

In all, 19 counties across northeast Colorado were affected by the floods. Tragically, eight lives were lost. Initial estimates place total damages at over two billion dollars, with 1,800 homes completely destroyed and thousands more damaged.

The geographic expanse of this disaster is humbling, but so too has been the response. While the people of Colorado embody a certain grit unique to the intermountain west, the outpouring of support from around the country and the world reminds us all of the enormity of this event, the power of the earth’s weather, and the sense of community that can span for thousands of miles.

An Overpass lays in ruin outside Lyons, CO one month after floods