Washington Week: Student Voices (O)

Researchers debate recent Colorado storms
By Nicole Danna
Colorado Daily (U. Colorado)
01/10/2007

(U-WIRE) BOULDER, Colo. — With the past three snow storms totaling over 40 inches in just under a month, have you stopped to wonder: Where's it all coming from?

For the meteorologists and research scientists studying the region's climate trends and weather patterns at the Boulder-based National Oceanic and Atmospheric Administration, the answer is one for debate.

According to Martin Hoerling, NOAA meteorologist involved in climate change research, the reason behind the recent snowfall events are ambiguous, but in line with trends presented by the El Nino effect.

El Nino is a naturally occurring warming of the Pacific Ocean, usually one Celsius degree difference, which produces excess moisture throughout the month of December and January and is a phenomenon that occurs cyclically — typically every three to five years.

Hoerling said research conducted by NOAA associate scientist Kathy Smith indicates that heavy snow events in December and January during the past 56 years are twice as likely during El Nino years.

Between 1950 and 2005, Hoerling said Smith's research indicates there have been 10 El Nino years, each registering 30 snowfall events of six or more inches during the months of December and January — snowfalls that are more frequent and leave behind more inches when compared to snow events during years when El Nino was not present.

In addition, Klaus Wolter, climatologist and research associate with the Cooperative Institute for Research in Environmental Sciences, has found similar evidence that snowfall increases during El Nino. After comparing the area's top 10 snowstorms from fall through spring since 1950, Wolter found that five of the 10 biggest snowstorms have occurred during El Nino, including the 29.9-inch blizzard Boulder received in 1997, the 20.8 inches that dropped in a 1998 storm, and the 22.5 inches left behind in 2003.

The most recent snowfall to occur during an El Nino year was the blizzard of 2006, which dropped 26 inches from Dec. 19-20.

But whether or not El Nino caused Boulder's most recent snowstorms is still questionable, Hoerling added.

"From a statistical point of view, you would expect El Nino is responsible for these [past three] storms Šgiven the increased risk of this happening, but then there is something that isn't fitting in these events, and that is where these storms coming from."

Commonly, El Nino generates a track of storminess that comes across the Pacific through the south of California, across to New Mexico, and then into our region, said Hoerling, but these storms have actually dropped in from the northwest, and that makes it rather unusual.

"The actual physical reason is elusive for us to answer, and we're not at all convinced that El Nino has been causing these storms," said Hoerling. "But this is an El Nino that is evolving on an ocean that is much warmer than it would normally be, which is of consequence when we're talking about climate."

Warmer weather may be the cause for El Nino, but according to NOAA Research Climatologist Henry Diaz, the area's recent weather pattern isn't due to either El Nino or a global warming trend.

"[These storms] aren't due to anything — weather just happens," said Diaz.

However, warmer temperatures — roughly 2 and a half to 3 degrees Fahrenheit more than average temperatures for the region — do set up a higher probability of getting severe storms because there is more energy in the atmosphere, said Diaz, who said record-breaking highs experienced across the U.S. in 2006 exceeded a 112-year record. Furthermore, said Diaz, these record-breaking highs are considerably more pronounced in the western U.S. than in any other area of the nation.

"The trend from 1895 has been roughly two degrees Fahrenheit [higher across the nation], and in the west it is more than that," said Diaz.

And with warmer temperatures come more pests, such as beetles, and more severe drought — which not even a few extra inches of snow will clear up.

Diaz said the nation's most severe drought on record occurred from 1997 to 2004, with the western region experiencing an even more pronounced drought from 2000 to 2004.

Still, due its altitude, Boulder temperatures remain only slightly higher than normal, said Bob Glansy, a Boulder-based National Weather Service meteorologist. Records show December 2006 averaged 35.3 degrees, only slightly above the normal 35.0 degrees Fahrenheit.

One thing that was above average, however, was the snowfall, which averages 10.2 inches for the month of December, but accumulated 45.5 inches in Dec. 2006 — a total of 3.05 inches of precipitation.

"We've been in a fairly dry period for some time, and this should really be helpful in getting moisture into the soil and reducing fire damage," said Glancy. "Midwinter snow tends to stay around longer, providing moisture to the soil slowly over time, and even though it's not good for drivers, it is good for the soil."

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