Looking back at autumn: Average season ends with chill

By Rachel Webber, College of Agricultural, Human & Natural Resource Sciences

AgWeatherNet-logo-250PROSSER, Wash. – Autumn weather in Washington typically becomes increasingly active from September to November, but that was not the case in 2013. September kicked off the season with a superstorm, one of the highlights of the fall.

Although the weather system was impressive on its own merits, the fact that it struck so early in autumn is remarkable, said AgWeatherNet meteorologist Nic Loyd.

A Web based, publicly available system, AgWeatherNet provides access to near real-time weather data and value-added products from Washington State University’s statewide weather network, along with decision aids for agricultural producers and other users.

September superstorm

September’s November-like storm spawned a variety of weather hazards that included heavy rain, strong wind and heavy snowfall. More than a foot of snow fell at Paradise, Mt. Rainier, while winds gusted to 71 mph in eastern Washington. Olympia received three inches of rain on Sept. 28 and five inches during the three-day storm.

“For many locations in western Washington, more rain fell during the normally dry month of September than in October and November combined,” said Loyd. “In fact, a few areas recorded nearly as much rain during the superstorm as they recorded in the following two months.”

Crop damage

But the monster storm was not the month’s only memorable weather event. On the evening of Sept. 15, a line of severe thunderstorms raced through central and eastern Washington. Some corn fields in the Tri-Cities area were flattened by 60 mph winds, and several AgWeatherNet weather stations recorded amazing 15-minute rain totals of around of one inch.

“Unfortunately, severe weather and thunderstorms during September caused areas of crop damage in central Washington,” said AgWeatherNet director Gerrit Hoogenboom. “Luckily, however, the remainder of the autumn season featured relatively uneventful and agriculture-friendly weather for the conclusion of the 2013 harvest season.”

Due to active and humid weather early in the month, along with cloudy weather later, a record warm September mean low temperature was recorded at Prosser.

Dry and calm

In marked contrast to September, October and November were relatively calm. October in eastern Washington was generally sunny and pleasant by day and cool by night. Western Washington was trapped beneath an inversion with fog and low clouds during much of the dry spell.

Still, October weather was not without variety. Nearly an inch of rain fell at the coast at Tokeland on Oct. 2. On Oct. 28, a Canadian cold front produced abnormally strong northeasterly winds in eastern Washington. The dry air that followed sent temperatures at Pullman to their lowest since January.

Chill ends warm spell

November began with somewhat mild and unsettled weather for the first 20 days. Then cool, dry air flooded into the region and high pressure built shortly after. Lowland areas east of the Cascades were dry and cool for the remainder of the month.

Highlights for the month included a high temperature of 64 degrees at Parker, near Yakima, on Nov. 19, as well as a low of 7 degrees at Moxee on Nov. 21.

As a result of the relatively inactive conditions, temperatures were slightly below average in October and November. Thus, September marked the end of Prosser’s 15-month warm period, while the autumn of 2013 marked the end of a six-season warm spell dating back to early 2012.



Nic Loyd, WSU AgWeatherNet meteorologist, 509-786-9357, nicholas.loyd@wsu.edu Rachel Webber, WSU CAHNRS Communications, 509-335-0837, rcwebber@wsu.edu