Q and A: Colorado state climatologist: Recent weather years extreme, but not totally out of the ordinary

News | June 10, 2013

Staff Reports

Nolan Doesken is the state climatologist for Colorado at the Colorado Climate Center at Colorado State University. Nolan began his work as a climatologist at CSU in 1977 and was appointed state climatologist in 2006.

Q: There’s the old saying in Colorado, “if you don’t like the weather, just wait five minutes” (or something like that). Is the weather in Colorado truly more unpredictable than other regions, or are there other areas of the U.S. that are just as unpredictable?

A: That same adage is used in many parts of the country.

The weather is changeable in most mid latitude and higher latitude regions — or anywhere that showers and breezes can pop up quickly.

But what is special about our area (and our neighbors to the north and south that also straddle the crest of the Rockies) is the large magnitude of change that can occur — even with clear skies.

It is not uncommon here in the fall on a perfectly clear day to have a high temperature of 70 degrees and a low of 25 degrees.

It would take a very strong cold front to make that happen in other parts of the country, but here it can just be a regular daily cycle when the skies are clear and the air is dry.

Also, the mountains very much disrupt the flow of air and moisture.

You can be watching the barometer falling like a rock and still the skies may be blue and the winds light.

Then all of a sudden the wind will pick up, the temperature will drop 30 degrees, clouds will quickly form and it will start to snow.

So back to your question — the weather has degrees of unpredictability in many parts of the country, but here (and in nearby regions of Montana, Wyoming, South Dakota, etc.) the magnitude of change and day-to-day variations is just plain large!

Q: You’ve been Colorado’s state climatologist for a number of years. Have the last couple years — with the 2011 record snowpack, the 2012 drought and the rapid bounce back in snowpack seen last month — represented the most extreme changes you’ve seen? How have other years compared to the volatility we’ve seen recently?

A: The flip flop from very, very wet (winter and spring 2011 and the high waters on the Yampa, Colorado, N. Platte and South Platte) to very, very dry (statewide in 2012) was definitely impressive.

The warmth of the 2012 spring followed by the cold this spring is surely attention grabbing.

In terms of back-to-back, year-to-year change, the high water of 2011 followed by low water in 2012 was the largest change in surface water supplies I’ve seen in such a short time (meanwhile both years were very dry in southern Colorado).

So yes, this is definitely a “volatile” period.

But when you look back at historic data there have been rapid fluctuations in the past.

The 1960s were like a roller coaster — very dry, then very wet, and then back again.

The big Thompson Flood of 1976 was followed by extreme drought the very next year and then was followed by some of our snowiest, stormiest years on record in the following two winters.

The drought of the mid 1950s was ended by one of Colorado’s wettest years on record — 1957.

So the more we look at the past, the more we realize that year-to-year fluctuations have always been large — no, huge.

Q: Along with temperatures and precipitation fluctuations, what have been some of the other interesting occurrences that have happened recently?

A: I can rattle off many examples of interesting occurrences.

The 12 inches of snow this month and the temperatures dipping into the teens in May was a really rare event.

The high rates of evapotranspiration last summer were downright scary. Even if you had an abundant water supply, it just seemed to disappear.

And hidden in with the drought and wildfires last summer was a weekend of wet weather, just after the 4th of July, that in any other normal year would have been viewed as really big and beneficial.

But last year, the 2-4 inches, depending where you were from July 6-9, just seemed to disappear (although they definitely put the finishing touches on the High Park fire.

Q: Predicting the weather in Colorado is difficult enough. What are some of the other challenges facing the Colorado Climate Center and other climate researchers?

A: While the Colorado Climate Center here at Colorado State University has been in existence for 40 years, funding has always been tenuous.

As is the case with many western states, we’ve relied on federal funds for much of our work — with the state only playing a fairly small role.

That is certainly changing right before our eyes, and that also may affect the availability of climate data (weather, snowpack, streamflow, etc.), much of which is collected via federal agencies.

Good quality data is what allows us to do useful work.

Things usually work out and find new equilibrium’s, but this is a substantial bump in the road.

Many people these days assume that most weather data are collected electronically — and that is largely true.

But most people have no idea how difficult and expensive it is to accurately measure rainfall and the water content of snow — information that is essential for managing our water supplies here in Colorado.

I never dreamed when I started my career here in Colorado 36 years ago that I would be begging people to put out plastic rain gauges in their back yards or at their offices.

But a careful observation by a careful person with a good, high-capacity rain gauge (like we use in CoCoRaHS), provides data that would require thousands and thousands of dollars to automate and which might never be as accurate.

Hence, we continue to actively recruit volunteers from all over Colorado and the entire country to help us measure and track precipitation.

Check out this website — CoCoRaHS.org — and please consider helping us measure and report rainfall from your place.

Q: A nd the dreaded question: What is weather outlook for the growing season for farmers? The spring so far seems to be wetter and cooler than many climate experts had predicted earlier. Are things now looking up for the summer?

A: T he indicators used to predict the next seasons — such as the El Nino Southern Oscillation Index, the Pacific Decadel Oscillation, etc — continue to point in the direction of continued heat and drought.

But it certainly hasn’t worked out like that in northern Colorado the past few weeks.

Seasonal predication months in advance is much harder than predicting 3-5 days in the future, and these long-range indicators are simply not always right.

I’ve looked back at some of our recent cool springs, and years like 1999, 1997, 1995, 1984 and 1983 come jumping out.

Those years with very cool springs — or at least cool Aprils — almost all turned out to have adequate to abundant growing season water supplies.

The old folklore that talked about cold, wet springs putting grain in the bins seems to have some truth to it.

But I’m sure if I looked farther I’d find plenty of exceptions.

One thing that I do like is the increasingly widespread precipitation in the plains the last few weeks and the gradually declining drought-stricken areas.

As we move into summer, more of the moisture that feeds our summer thunderstorms originate nearby from recycled water from evapotranspiration.