What A Difference A Year Makes


Nic Loyd; WSU AgWeatherNet Meteorologist; www.weather.wsu.edu

If you have been wondering when warmer, late spring-like weather will finally arrive, you are probably not alone.  Temperatures in Washington have generally been near or below normal since December.  In fact, the 2016/2017 winter season (December to February) was central Washington’s coldest winter since 1984/1985.  However, it is important to note that the recent chill in early 2017 is only half of the story.  Although the cold 2016/2017 winter and the lack of prolonged springtime warmth so far this year may seem highly unusual, it is not, in a historical sense, as abnormal as one may suspect.  Much of the surprise of the early 2017 climate is related to the extreme warmth of the mid-2010s, as well as the suddenness of the pattern shift toward colder conditions that occurred in December 2016.  The interval from the spring of 2014 until November 2016 was one of unprecedented warmth for central/eastern Washington.  In fact, the temperature anomaly of central Washington’s two-year period from mid-2014 to mid-2016 (+3.9 deg) was almost double that of the now-second warmest (non-overlapping) biennium on record (+2.1 deg; 1990 to 1992).

The 2017 accumulated GDD (Growing Degree Days) total (base temperature 32 degrees F) for Pullman (through April 24) was 747 units, which is somewhat below the 2009-2016 average of 829 units.  However, the 2017 value is well below that of recent years (1081 and 1149 units in 2015 and 2016).  These numbers are illustrative of the fact that the perceived chill of 2017, though somewhat justified, is partly the result of the stark contrast with the remarkable warmth of the previous two years.

January 1 to April 24 Accumulated Growing Degree Days

Base Temperature 32˚F
Location 2017 Recent Avg Difference
Pullman 747 829 -82
Ritzville 710 893 -183
Fairfield 663 763 -100


For further GDD information, please see Growing Degree Day Calculator.

Given the volatility of our recent climate, one may reasonably wonder what weather regimes are anticipated for the near future.  Seasonal outlooks for later in 2017 suggest modest but appreciable odds that the state’s temperatures will again become generally warmer than normal.  Long range weather forecast models and decadal trends show an enhanced probability of above normal temperatures this summer, although abnormally cool waters in parts of the nearby Pacific Ocean act to slightly diminish those chances.  There is also a slight tilt toward abnormal dryness, although few clear signals exist regarding potential seasonal precipitation anomalies for the summer of 2017.

El Niño is a critical question mark going forward, and its ultimate strength/presence should significantly influence next winter’s climate pattern.  Unlike the weak La Niña conditions during the chilly 2016/2017 winter season, the notable potential for a weak to moderate El Niño augments the likelihood of a relatively warmer and drier winter of 2017/2018.  However, despite some indicators such as dynamical forecast models pointing strongly in that direction, other tools including historical analogs are more tempered about the eventual evolution of a robust El Niño event.  Therefore, its ultimate development later this year is favored but not yet certain.  Regardless of how Washington’s near-term climate patterns unfold, it seems likely that we can expect additional climatic surprises in the coming months and years.

For additional weather data and decision support information, please visit AgWeatherNet’s website.  To find weekly weather outlooks for Washington State, please select Outlook from the main page of the website, or visit the current outlook page.

For questions or comments, contact Nic Loyd by email at nicholas.loyd@wsu.edu.