The Yampa River typically snaps out of its summer decline and begins to run with gradually increasing flows July 30, as seasonal thunderstorms stream up from the south.
But someone forgot to release the "hold" button this week.
"Right now we're in a monsoon break," Norv Larson said Wednesday. Larson is a meteorologist with the National Weather Service in Grand Junction.
Larson said a monsoonal weather pattern typically sets up by mid-July in the Colorado Rockies, as the Western Slope sees subtropical moisture from Mexico find its way north to the Yampa Valley via Arizona. Steamboat had a taste of the monsoons July 22, when lightning storms swept across the mountains surrounding Steamboat Springs. But the pattern was interrupted almost as soon as it began.
"There is high pressure in Arizona that is blocking the monsoons," Larson said. "There is some residual moisture, but we'll be pretty quiet into Saturday with the possibility of things picking up Sunday and Monday."
It's not unusual for oscillating high-pressure systems in the desert Southwest to block the monsoons off and on, he said. The current high-pressure system is due to slide east into Texas, he added.
"That opens the door for that subtropical tap," Larson said.
Despite several moderate episodes of rain showers in the past two weeks, Steamboat's July precipitation still lags abut an inch behind the July average of 1.54 inches for the month, local weather observer Art Judson confirmed Wednesday.
In spite of the scarce July precipitation, the Yampa continues to flow above the median for the date at the Fifth Street Bridge measuring station in downtown Steamboat.
The U.S. Geological Service was reporting that the Yampa was flowing at 188 cubic feet per second at midday Wednesday, 20 cfs more than the median for the date. Still, the river was trending gradually downward at a time when it historically begins to move up because of a rainy pattern.
The return of the monsoons also would increase the possibility of overnight thunderstorms in Western Colorado, as pulses of moisture flowing north from the Gulf of Mexico drift westward and get pulled in by the monsoonal flow, Larson said.
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