DENVER (CBS4) – It’s hard to believe we’re already talking about flash flood season in Colorado, but its true.

A flash flood watch continues for the Front Range foothills, the Palmer Divide and the area in and around Colorado Springs until 9 p.m. Tuesday.

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(credit: CBS)

(credit: CBS)

(credit: CBS)

(credit: CBS)

Colorado’s terrain and soils make the state very susceptible to flash flooding when wet weather patterns develop.

To complicate matters, area burn scars create an enhanced risk for flash flooding.

Water has a hard time infiltrating into soils that are changed by the intense heat of a fire and there is often little to no vegetation left to help slow the water’s flow.

Minor flooding in the Fourmile Fire burn area in May. (credit: CBS)

Minor flooding in the Fourmile Fire burn area in May 2011. (credit: CBS)


According to the USGS, there are 27,154 gallons of water in 1-inch of rain over 1-acre of land.

A square mile has 640 acres.

The Fourmile Canyon fire burned about 6,200 acres of land or roughly 9.5 square miles.

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When you do the math, the numbers are pretty astounding.

One inch of rain over the Fourmile Canyon burn scar produces approximately 165,096,320 gallons of water.

Assuming an olympic-sized pool holds about 660,000 gallons of water, that’s equal to about 250 pools.

When it comes to flash flooding the severity is determined by the rainfall intensity.

A slow and steady rain is a much better scenario than a downpour.

It’s always amazing to me to quantify precipitation in terms of gallons.

Water is truly an invaluable resource provided by Mother Nature.

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Meteorologist Chris Spears writes about stories related to weather and climate in Colorado. Check out his bio or follow him on Twitter @ChrisCBS4.