Northwest summers get hotter and hotter
The calendar says spring, but there’s still a chance that we’ll see some snow in the lower elevations through the middle of April. After the full moon cycle of April 7, Cliff and I expect the snowfall season to come to a close, especially in the lower elevations. However, the mountains may still see some flakes through the end of next month.
The 2.3 inches of snow that fell last Wednesday was a new daily record in Coeur d’Alene. The previous record was 2.0 inches set over 100 years ago, in 1916. Prior to the snow, temperatures warmed up into the lower 60s for several days.
With the possibility of more snow over the next several weeks, Cliff and I believe Coeur d’Alene’s seasonal snowfall total will end up around the normal of 69.8 inches. Amazingly, nearly half of this season’s snow came between Jan. 5-18. Overall, the winter of 2019-20 had the moisture, but it was milder than average. The coldest day of the winter also occurred in January as the lowest temperature of the season, which was 13 degrees, was reported on the 15th.
The early portion of our spring season looks a little cooler and wetter than average across the Inland Northwest. Conditions should then turn drier and warmer than normal later in May and June, assuming the current sea-surface temperature pattern does not change from a La Nada, the in-between warmer El Nino and cooler La Nina, to an El Nino. We also believe that the summer season will be similar to the one in 2019.
While doing research on temperatures for a number of projects, I came across several articles about how summer seasons are becoming longer in Australia and other parts of the world. We all heard about the disastrous fires in Australia in late 2019 and early 2020 during their summer season that was fueled by extended drought and record hot temperatures.
In the Northwest, the wildfire season of 2019 was considered relatively mild, especially when compared to previous years that had massive blazes and very poor air qualities. California had back-to-back disastrous fires in 2017 and 2018 that led to billions of dollars in damage. According to the U.S. Forest Service, since 1970, fire seasons in this country have expanded by an average of 78 days.
As I’ve mentioned in other columns, our planet’s temperature has been getting warmer. According to the National Oceanic and Atmospheric Administration (NOAA), 2019 was the second-hottest year in recorded history. The average temperature last year was 1.71 degrees Fahrenheit above the 20th century average. The hottest global reading, according to NOAA, was in 2016, with temperatures averaging 1.78 degrees higher than normal.
I put together a chart showing the trend of summer temperatures since 1950 in the Northwest. The “meteorological” months of June, July and August were used for calculation and the Spokane International Airport was used for location consistency. In Coeur d’Alene, some of the temperature readings since 1950 were taken in different locations and there were some data gaps in the 1980s. Although there are some minor differences in temperatures between Spokane and Coeur d’Alene, the data was the best source for this type of study and the purpose was to identify the trends.
Looking at summer temperatures, daily average readings of the high and low have warmed up nearly 3 degrees Fahrenheit since the 1990s. For the decade of the 2010s, the airport reported a reading of 68.76 degrees. In the 1990s, it was only 66.08 degrees. Therefore, our summer seasons are indeed getting warmer and perhaps longer, especially over the last 20 years. It’s quite possible that average summer temperatures in the last 10 years would be slightly higher had it not been for the haze and smoke that covered the region when we were experiencing disastrous wildfires.
Over the last five years, precipitation totals have been below normal levels during the summer. The combination of warmer and drier than average has led to record wildfire seasons not only in the Pacific Northwest, but other parts of the western U.S. It certainly looks like this trend will continue in the 2020s.
In terms of the annual average at the airport, the last decade has seen the greatest warming with an average reading of 49.00 degrees Fahrenheit. In the decades from the 1950s through the 2000s, average temperatures were 46.91 degrees during the chilly decade of the 1970s, to 47.89 degrees in the 1990s.
There are strong indications that the Earth’s temperature will continue to rise, based upon the burning of fossil fuels adding more carbon dioxide into the atmosphere. However, there may be other factors that increase the level of uncertainty of where the Earth’s climate will go in the next 10 to 20 years. As usual, only time will tell.
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Contact Randy Mann at randy@longrangeweather.com