Hurricane Rosa Approaches

A big storm in the equatorial Pacific has a lot of people’s attention. What will it mean for the canyon and the gorge? Widespread wind and rain are a certainty in the southwest — but how much will fall, and where?

Heavy rain runoff poses a grave threat to anyone caught inside the Little Colorado gorge at the time – that’s a given. Storms flows in this region have the power to change the landscape dramatically.

The Little Colorado is one of the largest uncontrolled rivers (no levees, dams) in the country. Storm runoff pours into the canyon with thunderous force, thick with silt, sediment and debris.

The Little Colorado River drainage is immense, reaching into New Mexico and nearly as far south as Phoenix 

Here is a video of two adventurists packrafting the Little Colorado River at 750fps above normal – enough to spike the adrenaline and increase the risk factor several-fold:

Things finally calm down right when they reach the (underwater) beach at the base of Salt Canyon. Look for the “foam finger” shaped rock – the most recognizable landmark amidst miles of sandstone.

Runoff flows from the plateaus above raise the river level and turn its turquoise waters to a muddy, chocolate-milk brown. After the skies have cleared, it can be weeks before the Little Colorado regains its original color.

There are two river gauges within the gorge. I took their data from April-October 2018 and tinted the charts to give an approximation of water conditions (turquoise vs. muddy) that would be expected at those times.

April – October, 2018 streamflow data for the Little Colorado River

This chart is fairly typical of the six-month summer period during many years. After the spring snowmelt, continuous warm, sunny days keep the region bone-dry until mid-to-late summer, when monsoon thunderstorms start to punctuate the trend.

From our experience, you can count on a snowmelt flow in March or April, a few scattered storms/fronts in May/June, and heavy, potentially life-threatening cloudbursts in late summer and early fall.

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