PULLMAN, Wash. – Following a cold 2011 and snowy start to 2012, the climate pendulum swung toward warmth in a big way for Washington state through the rest of the year.
Active and windy weather in central Washington brought the warmest November and autumn since the late 1990s, while December in Prosser was the second warmest since at least 1989. July to December featured above average temperatures east of the Cascades. In fact, December took the prize as the relative warmest month of 2012 with temperatures of 4.5 degrees above average.
Overall, 2012 was the warmest year at Prosser since 2003, with temperatures of 0.7 degrees
above average and 1.8 degrees above 2011 temperatures. Although other locations of central and eastern Washington were consistently 0.7 to 0.8 degrees above average, Mount Vernon’s annual average temperature was 0.2 degrees below average. June was the only month of 2012 with well below average temperatures statewide.
Cool weather gives way to heat waves
“Despite a plethora of unique meteorological occurrences last year, the Jan. 18 winter storm was the most exciting weather event of 2012,” said Washington State University AgWeatherNet meteorologist Nic Loyd. “Washington experienced everything from heavy snow and ice accumulations, to heavy rain and flooding, to bitter cold and strong winds during the week-long stretch of severe winter weather.”
A Web based, publicly available system, AgWeatherNet provides access to near real-time weather data and value-added products from WSU’s statewide weather network, along with decision aids for agricultural producers and other users.
Seventeen inches of snow fell in Centralia on Jan. 18, while much of the state also experienced heavy snowfall. Cooler weather in March gave way to heat waves during April and May, which distinguished spring 2012 from its chilly 2011 counterpart. Temperatures on April 23 were in the upper 80s in central Washington, while temperatures on May 15 were in the low 90s.
Despite the unique character of 2012, one similarity with recent years is that the late spring and early summer was cool and wet, while the later portion of the growing season was hot and dry.
The weather became cool and wet in June, as Prosser recorded rain on six of the first seven days of the month. Meanwhile in Pullman, the high on June 9 was only 48 degrees, and much of the state remained in the 50s early in June.
However, the weather changed quickly, as a muggy heat wave on July 8 sent temperatures as high as 107 degrees.
The second most notable weather event of the year – behind the January storm – occurred during the third week of July. An abnormally humid and stormy period began on July 14 and culminated with one of the most widespread severe weather outbreaks in recent Northwest history on July 20.
Many areas received golf ball-sized hail, thunder and lightning, strong winds and heavy downpours. Sunnyside recorded three-quarters of an inch of rain in only 15 minutes, while other areas suffered significant, hail-induced crop damage.
“Despite the severity of the event, the hail damage was highly variable,” said AgWeatherNet director Gerrit Hoogenboom. “While localized areas suffered severe damage, nearby locations were often entirely unaffected.”
Wildfires and a rainless streak
For the rest of the summer, the main story was hot and dry. August was much warmer than normal, while the streak of extremely dry weather continued in September.
Large Northwest wildfires and stagnant conditions resulted in some of the highest atmospheric smoke concentrations in recent memory throughout eastern Washington. Despite cloud-free skies, Wenatchee received only 40 percent of possible sunshine during several days in late September.
By early October, areas like Pullman had experienced more than 100 days without rainfall.
However, another rapid transition occurred in mid-October, as active and wet weather returned for the rest of the year. Long Beach had only seven dry days after Oct. 11.