WeatherWatcher: Cool Down, Long Range Warm

• Forecast
• Hot Weather
• Long Range

Forecast: We have a cool down coming this weekend. We might even see a sprinkle or two on Sunday. An on-shore flow (winds from the ocean) is starting up which should gradually transition us from this hot and dry weather to near normal conditions with morning clouds and afternoon sun. Highs will move from the mid 80's down to the mid-upper 70's and low 70's by the end of this weekend. More normal temperatures are expected to continue into next week, so a nice break from the hot temperatures we've had.

Hot Weather: From June 27th through July 6th, all but 3 days were 90°F or hotter for a high temperature. This entire year, and actually really starting last fall we have been above normal in daily average temperature on almost every day. There are several things going on that have combined to generate the warmest year on record. All of these things are natural variability that normally happen every few years, or every few decades, they just all happened at once this year, kind of like a conjunction. Below is a graph of our daily average temperature starting January 1, 2015. Blue is the normal average daily temperature, red is 2015's average daily temperature. You can click on the image to view the full size.

Daily Average Temperature 2016.

First and most popularly known, the ENSO (El Niño Southern Oscillation) is ramping up into the El Niño phase, which is the warm phase. It is currently at a +1.0°C anomaly, which is considered moderate, and forecasted to last through the fall and winter of 2015-2016.  It is very likely that this will be a moderate to major event as it currently already is moderate and it tends to peak in the fall and winter time frame. The other interesting thing with this El Niño event is that it started up last spring. It is unusual to have an El Niño during the late spring and strengthen during summer. Normally the ENSO neutralizes during the summer and ramps up or down during the fall.

A second lesser known oscillation called the PDO (Pacific Decadal Oscillation) is spiking with a warm signature right now. This oscillation normally flips every few decades from warm phases to cold phases. During these changes it will sometimes have a spike in one direction or another. The PDO started switching to a cold phase right around 1999. It had a warm spike in 2003, and again now. Before 1999 we were in a warm phase since about 1976. The phases usually last between 20-40 years. The current warm spike is what a lot of people in the media have picked up and started calling "the Blob" which is the warmer than normal pool of water in the eastern Pacific Ocean. This blob is actually fairly normal with these warm phase PDO spikes.

These two oscillations are not the only players effecting our global weather patterns right now but they are what I believe to be the major forces behind our current warmer than normal weather in the Northwest. Anthropogenic global warming is not a major force in this particular case. These cycles have been happening for centuries as historic data suggests. Remember official records for the Seattle region are from Sea-Tac airport and as such have only been recorded since 1945. 70 years in weather isn't a very long history considering some cycles take 150 or more years to collide.

Long Range:

What I think this means for our climate for the remainder of the year is that we will continue to experience warmer than normal temperatures with 1-2 week periods where we are near normal. A triple digit high temperature is possible this summer. Our fall and winter will likely be drier than normal, and warmer than normal. If El Niño goes from moderate to strong this fall and winter we could actually get near normal precipitation but still, warmer than normal temperatures, not good for the ski lovers and water supplies. There may be some struggle with water next summer (2016). 

I do believe there is light at the end of this very long tunnel. Historically when this pattern has occurred, it has ended after the second year. So when we get done with winter 2015-2016 our temperatures will likely start to return to near normal again, as well as precipitation. Winter of 2016-2017 may be a winter to watch out for if major lowland snow events are your concern.