Weather and Climate

 

Weather and climate change; words seemingly in the news almost each day. Ask anyone what Seattle's weather is like and you'll hear words like rainy, cool, wet, stormy, drizzly and fickled. Temperatures within a 20 mile radius of downtown Seattle can vary as much as 15 degrees. Often many visitors to downtown Seattle are surprised by the amount of abundant sunshine and lack of precipitation.

Many factors account for the disparity of weather conditions throughout the region. What are some of these conditions that cause weather to vary from location to location? While there's no doubt that the climate has changed in this region, what will the future be like? Will Seattle's weather be more like Los Angeles or Anchorage? Will Puget Sound be covered by ice, as it was 15,000 years ago or will all our surrounding glaciers melt and disappear? Will climate change bring extremely heavy rain and less snow as some future climate models suggest?

 

In 2012, as the rest of the nation experience the hottest spring and summer temperatures ever, here in the Northwest we had cooler than normal weather. A weak La Niña and a negative phased Pacific Decadal Oscillation (PDO) were thought to be the main causes for these conditions.

Originally, conditions during late-summer 2012 were trending to increasing El Niño conditions and a negative phase PDO in the north Pacific. Since then, while the PDO hasn't changed much, the mid-Pacific ocean conditions have trended from a weak El Niño to a more neutral condition. What does the winter forecast now look like for the Northwest?

The forecast of a drier and warmer winter have changed to normal wet and cool weather, but with the possibility of one or more major wind, snow, and rain events. The forecast of a winter drought now are poised to be a winter to remember! Stay tuned.

 

The following winter forecast predictions were made based on a compulation and interpretation of winters that had neutral to medium El Niños during the past fifty years. While not considered for these forecast, other phenomena, like the Arctic Oscillation and Pacific Decadal Oscillation, can affect the weather in the Northwest in various ways. more

 

Forecast for 2012-1013 winter temperatures

Tim Karle

 

Last winter's La Niña lasted longer than originally thought, but eventually by spring, returned to a neutral phase. It now appears that these conditions will remain and influence what the Pacific coast's weather this winter and early spring.

 

Winter 2012-2013 may have normal periods of precipitation punctuated by extremely strong precipitation events.

Tim Karle