PULLMAN, Wash. – In January, warm air was barely out of reach yet still hard to imagine for most winter-weary Washington residents.
A ridge of high pressure dominated the weather during the middle of the month, bringing warm, dry and sunny conditions to the mountains. In fact, parts of the Cascade foothills soared into the 70s on Jan. 15. In June, the same weather pattern would have meant hot temperatures across the state.
However, due to lack of wind or frontal passages, most of the populated lowland regions of the state remained locked in cold air. During the peak of the cold spell, highs were only in the 20s throughout central Washington, said Nic Loyd, Washington State University’s AgWeatherNet meteorologist.
“The problem was not a lack of warm air, but rather the lack of a mixing mechanism to transport that mild air to the surface,” he said. “The presence of a calm air mass, a cold surface and a weak winter sun set the stage for a prolonged stagnant period of the gray days of winter.”
The stable surface layer meant low clouds and poor air quality. Despite the shallow nature of the inversion, which was only hundreds of feet deep at times, there was a huge vertical temperature gradient between the cold surface and the warm atmosphere.
Active, stormy periods punctuated the calm, bringing rain to western Washington and windy, mild conditions to eastern areas Jan. 7-10 and toward the end of the month. Winds stronger than 60 mph struck Wenatchee Heights on Jan. 7, while temperatures rose into the mid-50s near Walla Walla.
Weather extremes included nearly two inches of rain at Long Beach on Jan. 9 and a low temperature of one degree at Broadview on Jan. 13.
January temperatures were below average overall in the lowlands, especially during the day. The average high temperature at Prosser was 35.4 degrees – 4.2 degrees below average and the coldest since 2004. The recent cold, however, was the result of a strong inversion, rather than an arctic outbreak – as occurred in early January 2004.
The coast was one of the few lowland locations that saw mild weather in mid-January. Despite lows in the 20s, Long Beach temperatures managed to climb into the 50s during the day.
Overall, the lack of extreme or adverse weather spared the mostly dormant fields and orchards, said AgWeatherNet director Gerrit Hoogenboom.
“Luckily, most fields and crops are faring well this winter, and there have not been any reports of weather-related damage so far,” he said.
For more information, please see the January 2013 Weather Review on the AgWeatherNet website, http://www.weather.wsu.edu, under the News Link.