New long range forecasts suggest wet spring, hot summer around Seattle
February will at least go down as among the Top 5 wettest in Sea-Tac history (and has a reasonable shot of making Top 5 all time in Seattle), and the latest forecasts suggest the rather wet pattern may stick around into the spring.
NOAA is out with their monthly updates on their long range forecasts and most of the maps are rather benign for the Northwest. With La Nina declared done and the central Pacific Ocean in the "neutral" phase which tends to release any large scale influence it has on global patters, the forecast for March has equal chances of above/below or normal rainfall and temperature. Or as I call it: The "grab a dartboard" forecast. (No jokes about typical daily forecasts also using this manner, please. OK, maybe one. But just one! So make it a good one...)
However, there is one signal that they've picked up on for their 90 day seasonal forecast for spring: A slightly enhanced chance of a wetter than normal spring.
NOAA forecasters say some of the current models suggest the northern tier states will be a little wetter than usual this spring.
Now, these seasonal forecasts haven't been batting 1.000 over the past few years but the wet spring forecast actually has a second collaborating forecast: The QBO forecast.
No, I'm not making up that acronym (because if I were, I'd at least use something more valuable in Scrabble like "The QZV Forecast") -- it stands for Quasi-Biennial Oscillation.
It's part of the research Utah State graduate student Jason Phelps has been doing that matches correlations between weather patterns in the West and a slowly oscillating wind high up in the atmosphere.
I've written about Phelps' research and the QBO wind before, but here is a quick refresher course:
The QBO is a slowly oscillating wind about 15 miles high above the equatorial regions of Earth (where air pressure is 30 mb, or 0.89" of mercury) -- well above the daily grind of weather patterns. Research shows the wind slowly alternates between west and east over a period of 12-18 months, making a full cycle every 18-36 months (averaging about 2.2 years). The wind, which reaches peak speed of about 30-40 mph in either direction at its maximum, creates a chain reaction of events in lower altitudes which can eventually manifest itself in a stable weather pattern.
What Phelps has found so far is that depending on what months the QBO reaches its maximum phase and whether it's in its positive (west) phase or negative (east) phase, the event does seem to account for overall weather patterns here with some regularity. And if you look in the past blogs I've written about Jason's QBO, his predictions have come out to be pretty darn accurate, including the wet spring then intense heat waves of 2015.
This year? He thinking we'll have a wet spring again. The westerly wind in the current phase of the QBO hit record highs in December and January and the years that held the previous records all had very wet springs.
"Some past wet springs such as 2014 and 2011 both had very strong westerly QBO indices like this year. Only this year the westerly QBO index is even stronger," Phelps said. "So, could be looking at a very wet February, March, April, maybe into May for western Washington this year."
That would be nice if it could combine with some cooler weather to extend the snow season a bit into summer.
What about Summer? Will Olaf be happy?
Speaking of summer, long range forecasts from NOAA think in general, it'll be another toasty one across the nation, especially along the West Coast:
Phelps' QBO observations concur.
"The three most extreme cases of strong westerly QBO winds like we have this year (1967, 2009, and 2014) were all definitely hotter than normal summers in Washington and Oregon," he said. 1967 holds the hottest August on record, 2009 holds the hottest date on record, and 2014 had several days over 85 that seemed like a hot summer until 2015 came along with "The Blob" and blew it out of the water.
The other interesting items those three years had in common were wet springs.
"2014 was a record-breaking wet spring, 2009 was wet and that year there was snow way late into April at Sea-Tac," Phelps said. "And 1967 was a cooler/wetter spring as well. Then all three of these years it boomeranged in the summer, with a hotter than normal summer."
Phelps provided this map showing a composite of the summers of 1967, 2009 and 2014 relative to average temperatures and the Northwest is toasty:
We'll see if it holds again this year and if Olaf will be busy counting up the Seattle Summer Minutes!