UW Today

August 1, 2011

Did you think it was a cold spring? Now you have the proof

News and Information

If youre one of those lamenting the colder-than-usual spring and summer in Washington, youve got some supporting evidence. A University of Washington researcher has found that, at least by one measure, it was the coldest spring on record for the state.

To top it off, records show that Seattles last two springs have been the cloudiest since cloud-cover records started 50 years ago.

This graph shows that the statewide average high temperature for the period of April, May and June 2011 was the coolest for any spring since 1900.

This graph shows that the statewide average high temperature for the period of April, May and June 2011 was the coolest for any spring since 1900.James Johnstone

“We were still getting wintertime cloud cover into late June, which is the most remarkable aspect to me,” said James Johnstone, a research associate with the Joint Institute for the Study of the Atmosphere and Ocean in the UW College of the Environment.

To make his temperature calculation, Johnstone gathered daily high temperature readings for April, May and June from 44 stations across Washington state. Most of those stations had temperature histories going back to 1900.

He found that the statewide average high temperature for April through June was 60.4 degrees Fahrenheit this year, easily the coldest average temperature going back to 1900. The second-coldest was 61.6 F in 1955. The overall average high temperature in the April-June period for all years since 1900 is 65.6 degrees, and some years have had averages above 70 degrees.

For Seattle, the 60.4 F average high temperature for this spring was second-coldest on record, surpassed only by the 59.6-degree average in the spring of 1920.

“The people who have been complaining about the weather have had a right to complain,” said Nick Bond, a UW research meteorologist with the joint institute and the state climatologist. “I rather like it, but thats my own character flaw.”

Bond noted that with typical atmospheric dynamics, when a large area is exceptionally warm such as the central and eastern United States have been, it is not unusual for an adjacent area to be substantially cooler as much of the Pacific Northwest has been.

This graph shows that the period of April, May and June in 2010 and 2011 were the cloudiest springs on record at Seattle-Tacoma International Airport.

This graph shows that the period of April, May and June in 2010 and 2011 were the cloudiest springs on record at Seattle-Tacoma International Airport.James Johnstone

But for many people in the Seattle area, it wasnt just the cool temperatures – it was also the dreary feeling of prolonged cloud cover. Johnstone found supporting evidence for that too.

He examined cloud cover records from Seattle-Tacoma International Airport and found that April through June this year averaged 18.6 hours per day when there was at least 50 percent cloud cover. That is second only to spring of last year, which averaged 19.1 hours of cloud cover per day.

“Weve had the two cloudiest springs on record in Seattle the last two years, which is kind of odd,” Johnstone said. “I think its just a run of two bad springs in a row. I wouldnt expect it to happen again and again and again.”

He noted that the spring started with higher-than-usual rainfall, which steadily declined, and lower-than-usual temperatures, which steadily increased. But an unusually high level of cloud cover persisted.

Typically, the storm track present in Western Washington during the winter begins moving into British Columbia around April. “That hasnt happened this year,” Johnstone said.

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For more information, contact Johnstone at 206-685-0317 or jajstone@uw.edu or Bond at 206-526-6459 or nab3met@uw.edu.