PROSSER, Wash. — Sometimes you have to see the game to understand what really happened. If ever there was a time when the scorecard failed to capture the essence of an event, it was this winter. “Although Washington’s 2011 – 2012 winter season was fairly average according to the numbers, it was far from a typical winter. As is often the case, the most interesting aspects of winter lie not in the averages, but in the variability and complexion of the season,” said AgWeatherNet meteorologist Nic Loyd.
Despite the fact that temperatures at Prosser were close to average over the December to February time period, there was lots of action occurring behind the scenes. December was very dry, with almost no precipitation across the state until Christmas. The month was also one of the driest La Niña Decembers on record. High pressure maintained unusually warm conditions in the mountains, but stable conditions prevented the mild air from mixing to the surface. As a result, December was slightly cooler than normal and very stagnant in the central Washington lowlands, despite the warmth aloft. A series of strong and warm storm systems brought rain and wind to Washington at the close of 2011, giving Prosser its warmest December day on record on the 28th.
Although much of January was uneventful, winter forcefully appeared in Washington around mid month. A series of winter storms from January 14 to 23 produced a variety of weather hazards that included heavy snowfall, significant ice accumulations, cold temperatures, heavy rain, flooding, and wind. Up to 17 inches of snow fell in western Washington in the Centralia area in less than 24 hours, while heavy snow also fell in much of eastern Washington on January 18. The following day brought significant ice accumulations to some locations; freezing rain fell for much of the day in the Tri-Cities, while up to 1 inch of ice coated the east Puget Sound lowlands.
Heavy rain and warmer weather eventually led to flooding by January 20 in parts of western Washington. Snow fell for several days in some areas east of the Cascades, leaving places from Yakima to Wenatchee with a foot or more of snow on the ground by January 22. Some areas in the Cascades received up to eight feet of snow during this brief period of extreme winter weather. Overall, January had near average temperatures despite the variability of conditions during the month.
February was a typically active late-winter month that featured periods of notable weather, although nothing as extreme as the mid January snow and ice storms. Strong winds on February 21 and 22 brought warm temperatures to central Washington. Winds gusted to over 60 mph at times, while some parts of the lower Yakima Valley neared 70 degrees. February ended with cold temperatures and snowfall, even at areas near the coast.
“Several winter storms in mid to late February brought moderate snowfall to the mountains, which is good news for Washington growers since the weather systems augmented the Cascade snow pack to around normal late winter levels,” said AgWeatherNet director Gerrit Hoogenboom.
For more information on Washington’s winter weather, please see the Winter Weather Review on the AgWeatherNet website, www.weather.wsu.edu, located under the news link. 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.