Drought/runoff news: Next up, the North American Monsoon?



I ride a bicycle to work most days and for most errands so rain in the forecast is always a pain in the derriere. I also work for a water provider faced with a vanishing snowpack and a huge increase in consumption this spring. The realization that our storage will not fill as usual has us looking hopefully at the coming monsoon season both for summer stormflows to divert and to dampen demand for outdoor irrigation.

Meterologist, Brian Bledsoe, is optimistic about the monsoon and for the prospects of a cold and wet fall, according to a report from Chris Woodka writing for The Pueblo Chieftain. From the article:

“I’m most encouraged that we’re going to see a summer monsoon season,” television meteorologist Brian Bledsoe told a drought preparedness workshop last week at the Colorado State Fairgrounds.

The workshop attracted about 50 people, mostly farmers and ranchers from Pueblo, Fremont and Huerfano counties. The daylong event provided information about rangeland management, weed control and farm economics as the area endures its second year of drought. After an early runoff, state snowpack is at 12 percent of average.

While many weather forecasts pay attention to the broad trends associated with La Nina and El Nino — cooling or warming of the Pacific Ocean — there are other climate patterns that influence Colorado’s weather, Bledsoe said. A particularly good indicator is the highly variable Madden-Julian Oscillation, which originates in the Indian Ocean. Other seasonal and multiyear patterns over the Pacific Ocean and North Pole play a part, as does the solar cycle.

The upshot of Bledsoe’s calculations show a good chance that La Nina is over and El Nino is coming. That could mean heavier rains in late summer and fall, like the region saw in 2009, the wettest year of the decade in Pueblo.

The winter is also likely to be colder than usual, with chances of snow depending on what happens with moisture in the Southwest U.S. in the next few months. Conditions could be similar to the winter of 2006-07, when several blizzards hit the Eastern Plains.

Bledsoe showed several climate models that predict with some certainty that an El Nino is brewing in the Pacific Ocean, which usually means more moisture for Southern Colorado. The projections vary wildly as they go further out in time, but there is some degree of confidence that patterns will change in the next few months, he said.

From Steamboat Today (Matt Stenslund):

Conditions are drastically different compared to last year, when record snowpack led to a swollen Yampa River…According to preliminary data from the Colorado River Basin Forecast Center, the flows on the Yampa peaked this spring on either April 27 or May 6, when flows were measured at about 1,570 cfs. The peak will not be made official until the data is analyzed this fall.

Craig Peterson, a hydrologist with the Forecast Center, said the earliest peak on record for the Yampa downtown was April 26, 1974, when the flow was measured at 5,790 cfs. The records go back to 1904.

According to data from the Tower snow measuring station 10,500 feet above sea level on Buffalo Pass, 35 inches of snow remains, containing the equivalent of 16.3 inches of water. The historic average snow-water equivalent for May 18 is 50.7 inches of water. On May 18, 2011, the snow-water equivalent at the Tower measuring station was 74 inches, which was 146 percent of average, and the number still was growing. The snow-water equivalent did not peak last year until May 29, when the snow held 80.1 inches of water.

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