The past two years have been quite warm for the Pacific Northwest. 26 of the past 28 months have had above-normal temperatures, including every month this year. Along the way, all-time average temperature records were not only broken, they were smashed, with March 2015, April 2016, June 2015, and October 2014 obliterating previous average monthly temperature records at Sea-Tac. And let’s not forget the historic snow drought of 2014-2015 and the terrible wildfires that ravaged the eastern portion of the state the past two summers. With global warming, we should expect warmer temperatures, but this warm streak we’ve seen since 2014 has been unprecedented in many respects.
Recent Temperatures compared to average.
Credit: University of Washington Atmospheric Sciences Department
However, we’ve been pretty darn cool over the past couple weeks, and as the graph above shows, the temperatures really haven’t changed that much over the past few months. On average, they’ve gotten a little higher, but the magnitude of the change is far less than we would expect. Moreover, we haven’t seen a consistent trend with our minimum and maximum recorded temperatures of each month. April hit 89 and 43. May was 87 and 46. June was 93 and 44. That is amazingly consistent. Moreover, June was actually wetter than both April and May, so even if it is getting warmer, we’ve generally been getting cloudier and rainier, and it has felt as though summer is leaving us, not greeting us. Our saving grace is that the days last forever, but now that the solstice has passed, our days will be getting shorter as well.
Is there any hope for us in the future, or are we doomed to have a gloomy summer?
First off, I don’t think gloomy summers are a bad thing. Our past summers have been such scorchers that it is nice to have a relatively cool summer for a change. And, keep in mind that even though it may feel cool, we’ve still been above-normal in the temperature department. This past June was the 8th warmest on record for Sea-Tac airport.
In any event, it’s hard to know whether we will see a gloomy summer or not. Long range models have consistently forecast a ridge of high pressure over our area, directing storms to the north and keeping us high and dry. Instead, we’ve seen an unseasonably deep trough as of late, generating low snow levels, low clouds (especially in the morning), and rain at times. Long range forecasts are going for warmer and drier than normal, but I do not have a lot of confidence in these forecasts. They were terrible this past winter, consistently forecasting below-average precipitation for the Pacific Northwest when in fact, the Pacific Northwest had well-above-normal precipitation, breaking all-time monthly and seasonal precipitation records in many spots.
First, let’s take a look at the near-term.
Right now, we have a big trough over our area, with a big ridge in the eastern Pacific. This is an unusual pattern for July, and it is the culprit for our unseasonable weather. This general pattern is actually the type of pattern we see when we get gobs of snow in the mountains in the winter, and although it is far too warm for snow at Snoqualmie Pass now, if we were in a similar setup in January, you could bet that chains would be required driving across Snoqualmie Pass.
The models have been very consistent in keeping this trough overhead and keeping us cooler than normal. Here’s the same chart 5 days in the future. Very similar!
The picture above shows the temperature and precipitation predicted by a model with slightly different initial conditions (these are called ensembles). The important thing to look at here is the ensemble mean (white line), which is generally cooler than average for temperature (red line) for the next two weeks.
The Climate Prediction Center is predicting warmer and drier than normal in a month. But I wouldn’t hold your breath…
And as soon as I finished this blog, it starts raining cats and dogs (for summer) over downtown Seattle! Expect light rain off and on tonight. Tomorrow will be better, especially in the afternoon.
