El Niño and the Monsoon

We are entering monsoon season in Colorado, a time when a seasonal wind shift brings moisture up from the Pacific and Sea of Cortez, sometimes a little moisture, and sometimes a lot- monsoonal flow created the extreme rainy weather of September 2013, causing some of the worst flooding in the history of the state.  On July 31,1976, a storm dumped huge amounts of rain in the Foothills and created a flash flood in Big Thompson canyon, killing 144 people. 

The increasing probability of a moderate to strong El Niño emerged in late winter and early spring 2014. In fact, recent observations (as of June 12, 2014) of sub-surface ocean waters in the equatorial Pacific region show a massive volume of anomalously warm water several hundred feet below the ocean surface. Very similar conditions were observed in Spring/early summer 1997, which resulted in the warmest/strongest El Niño on record.

Historically, moderate to strong El Niño episodes have featured a slightly increased frequency of occurrence of above normal precipitation during November-December. For the January-March period they have featured above normal precipitation (generally 110% to 140% of normal) over the eastern half of the state.

This year an El Niño cycle, which pushes coastal moisture over the mountains, will add more water to what might be an already robust monsoon, said Mike Baker, a forecaster for the National Weather Service in Boulder.

"We always see the monsoon and it comes in different flavors and strengths," he said on Tuesday. "We may be dealing with an enhanced monsoon."

For the first time in years, much of the state has been free of drought for months, according to the U.S. Drought Monitor. The monsoonal rains should add to the state's already full reservoirs and high-flowing rivers.

"Once it gets going in the next couple of weeks when the high pressure shifts, we'll be under the gun and will get our fair share of rain," Baker said.

For regular readers, you know this is where I expound on the wisdom of calling WeatherSure sooner rather than later, and making sure the “enhanced monsoon” doesn't create any property management disasters, huge headaches or angry tenants- just remember, for those who have planned ahead and taken care of building envelope maintenance, the rain is a welcome thing in this dry part of the world.