Summer was very warm at times and very very dry. We just passed a milestone in the year that represents the change of season to Autumn. The next season that, in this summer of so many wildfires, is one we have really looked forward to arrives in less than a week. The season is our rain season also known as the water year. It officially begins on October 1st for the Southern Willamette Valley and continues through September 30th. The rain we have recently received has been very beneficial in the battle against the insidious wildfires that have plagued our state for many months.
Let’s take a look at last year’s water year for Eugene. The water year that ran from October 1st 2015 to September 30th 2016 received 40.58 inches of precipitation which is 5.52 inches below normal. That means that 45.80 inches of rain is what is considered to be the normal precipitation measured near Eugene’s Mahlon Sweet Airport. The yearly rain total measured from January 1st through December 31st 2016 was 41.33 inches of rain which is 4.77 inches of rain below normal. The normal rainfall for the calendar year in Eugene is listed as 46.10 inches of rain.
Here are the monthly precipitation totals for Eugene for the water year 2016-2017. We start with October 2016 in which 10.19 inches of rain fell and that is 6.94 inches above normal. November’s total was 4.30 inches of precipitation which is 3.42 inches below normal. December’s total was 5.10 inches which is 2.73 inches below normal. Now we slide into 2017. January saw 4.05 inches and that was 2.82 inches below normal. For February the total was 9.33 inches which is 3.90 inches below normal. The month of March was close to normal with 5.82 inches which is 0.83 inches above normal. April had 3.65 inches fall and that is 0.32 inches above normal. Now we start to see the effects of the more serious drying. The month of May saw 1.22 inches of rain which is 1.52 inches below normal. June’s total was 1.38 inches which is 0.12 inches below normal. July was really dry with only 0.02 inches if rainfall measured and that is 0.52 inches below normal. Similarly,the month of August saw only 0.14 inches of rain which is 0.47 inches below normal. And finally to wrap up the water year 0.92 inches of rain fell in September which is barely above normal by 0.06 inches. So, for the water year 2016 to 2017 the total precipitation received (rainfall plus the water content of any melted snow that fell) was 45.99 inches. That factors out to 0.19 inches above the 45.80 inches considered to be the normal for our water year.
Those numbers may seem quite surprising since our summer seemed so dry for such a long period of time. That dry weather combined with the number of thunderstorms produced by passing storms is what helped give us a very bad wildfire season.
The 90-day precipitation outlook for the three months of October, November, and December shows the Pacific Northwest in an area with about a 40% chance of above normal precipitation for that period. I’m sorry to say that doesn’t give us much of an insight into exactly how much we will actually get, but is at least an indication of the trend for that period of time.
Here’s a quick look at the 90-day temperature outlook for the same period on October, November, and December. By the look of it we are in the area of a 40% chance or less of above normal temperatures over the three months.We could extrapolate from these two maps that the Pacific Northwest has a less than 40% chance of having warmer and wetter weather than what is considered normal for the 90-day period.
To be honest, flipping a coin statistically gives a 50% chance of either heads or tails which is better odds than the 90-day outlook predictions.
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