TORONTO – Relief for the people in northern Colorado is finally in sight.
The area experienced a deluge of rain for the past seven days as a persistent weather system hung in place above the area.
“It was drawing up a lot of subtropical moisture from the south and southwest, from New Mexico and Arizona,” said Scott Entrekin, a meteorologist with the National Ocean and Atmospheric Administration out of Boulder, Co. “The problem is, it never really moved. It’s actually just moving across the state now, so it just kept bringing up that moisture for days and days.”
Although most people associate monsoons with the tropics, the United States has its own monsoon season which typically affects Arizona and New Mexico during the months of July and August.
Monsoons, though associated with rain, are actually a shift in wind pattern from northeast to southwest. For Arizona and New Mexico, that means that moisture is drawn up into the area from the south, where the heating from the mountains plays a major role in triggering high precipitation events. Ultimately, it also can affect neighbouring Colorado.
“Typically, we get a lot of this monsoonal moisture in July and early August,” Etrekin said. “So it was very unusual that a lot of this moisture was still coming up in September…It’s been a psuedo monsoon.”
On average, Denver, Co., sees a total of 24 mm of rain for the month of September and an annual total of 363 mm, according to NOAA. Over the last week alone, NOAA reported 160 mm.
Boulder reported 536 mm of rain was reported in the same period.
To put that in perspective, during the Alberta floods, Calgary received a monthly total of 146.6 mm of rain.
Similarly, both Boulder and Calgary are both located near the bottom of mountains. Any towns or cities that lie at the bottom of a mountain run the risk of flooding during heavy and persistent rains, as the water moves downhill through water and streams. Landslides are likely as the saturated ground is unable to hold together and falls apart.
As of Tuesday, NOAA is calling for mostly clear skies for Boulder.
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