Warmest winter since 1992 ends with warmest February

By Seth Truscott, College of Agricultural, Human & Natural Resource Sciences

agweathernet-logo-250PROSSER, Wash. – The last time Prosser experienced a month as warm as February 2015, relative to normal, some people were still using typewriters and cordless telephones.

According to Washington State University’s AgWeatherNet, the February monthly anomaly was up 5.9 degrees overall and up 6.7 degrees for the mean monthly high.

A WSU AgWeatherNet monitoring station near Spokane is snowless in December.

A Web-based, publicly available system, AgWeatherNet (http://weather.wsu.edu
) 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 is based at the WSU Irrigated Agriculture Research and Extension Center in Prosser.

Most unusual season in decades

Temperatures were particularly mild during the early to middle part of February. Parts of central Washington recorded highs and lows in the 60s and 40s, respectively, which is nearly 20 degrees above normal for that time of the year.

Active and wet weather early in the month gave way to drier and mainly uneventful conditions for much of the middle to latter part of February.

This winter – December to February – was the warmest since 1991-92, with a mean anomaly of +3.5 degrees. The 2014-15 winter was not only one of the mildest winters on record, but also one of the warmest seasons, relative to normal, in recent history.

“Not since the spring of 1992 has a seasonal mean temperature been farther above normal,” said AgWeatherNet meteorologist Nic Loyd. “In fact, this winter featured the greatest absolute seasonal departure from normal since the cool summer of 1993. In other words, it was the most unusual season in 22 years.”

Snowpack at record lows

Aside from cold periods around Dec. 1 and Jan. 1, nearly the entire winter was anomalously warm and snow-free. Somewhat stormy weather in December gave way to occasional wet spells interspersed with prolonged dry periods after the New Year. However, wet periods were anomalously warm and cold periods were very dry. As a result, the mountain snowpack is at record or near-record low levels, which could become a greater concern later in the summer.

“Unfortunately, the generally benign winter was not without agricultural consequences,” said Gerrit Hoogenboom, AgWeatherNet director. “Much of the eastern Washington winter canola crop was devastated by the mid November arctic blast. The rapid, early season transition from warm to cold temperatures was especially damaging due to the associated strong winds and lack of insulating snow cover.”

Temperature extremes

Highlights of the 2014-15 winter include various temperature extremes and rainfall events. At WSU Tri-Cities, temperatures soared to 68 degrees on Feb. 7 and reached a balmy low of 47 on Dec. 21.

More than an inch (1.27 inches) of rain was observed at Pullman on Dec. 19 and 20, and 1.04 inches fell on Feb. 9. On Dec. 30, Pullman experienced one of the few cold days of winter, with a high of 16 degrees and a low of 4.

Long range outlooks for Washington favor the continuation of warmer and drier than normal conditions into early 2016. Unless that trajectory changes significantly, the state could be facing another long, hot summer.


Nic Loyd, WSU AgWeatherNet meteorologist, 509-786-9357, nicholas.loyd@wsu.edu
Gerritt Hoogenboom, WSU AgWeatherNet director, 509-786-9371, gerrit.hoogenboom@wsu.edu