PROSSER, Wash. – In a year of meteorological wild cards, December took the last trick. Despite the presence of La Niña, which favors wetter and snowier than normal winter conditions, December was unusually dry and calm across Washington. Low clouds and poor air quality were the most notable weather concerns of the month.
“Normally, December is one of the more active weather months of the year,” said AgWeatherNet meteorologist Nic Loyd. “However, a strong ridge of high pressure blocked the storms that might have otherwise reached the Northwest. The high-pressure system persisted over the region from the end of November through Christmas. As a result, Washington experienced very little interesting winter weather until the final week of the year.”
Mountain snowfall was very low in December, and the Cascade snowpack remains below normal at the beginning of 2012. Northwest Avalanche Center data indicate that mountain snow depths ranged from 55 to 103 percent of normal on January 1. However, Paradise and White Pass snow depths were at record low levels for a La Niña winter like this one. “If the mountain snowpack remains below normal, it could have a negative impact on available water for irrigation during the summer,” said AgWeatherNet Director Gerrit Hoogenboom. Even so, there is still a chance to recover from the current snow deficit if heavy snows materialize during the later part of winter.
At year’s end, increasingly unsettled weather brought heavy rain to the coast, and strong wind and unseasonable warmth to eastern Washington. Prosser experienced its warmest December day on record on the 28th, and the daily low temperature of 52 degrees smashed the old December record by four degrees. Long Beach recorded two and a half inches of rain from December 28 – 29, while winds at St. John gusted to over 50 mph, while in the Walla Walla area, temperatures jumped to around 60 degrees.
Ironically, December was a noteworthy weather month precisely because of the uneventful and dry weather conditions observed until Christmas. And the current forecast suggests a continuation of the status quo with little chance for significant wintry weather in Washington for at least the first two weeks of 2012. However, the longer-term climate outlook from the Climate Prediction Center still suggests enhanced odds of cooler and wetter than normal conditions in Washington through the spring of 2012.
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. It includes 137 weather stations located mostly in the irrigated regions of eastern Washington State, but the network recently has undergone significant expansion in western Washington and in dry land regions of the state. AgWeatherNet is available at www.weather.wsu.edu.