A wet & cool Pacific Northwest spring will continue
Memorial Day weekend just over 2 weeks away!
I’m hearing lots of complaining the past week or so as our chilly spring weather goes on. These last two days were quite reasonable with partly cloudy skies and dry conditions (for most of us). But even with the dry weather, we only made it within 5 degrees of normal today!
That’s because we’re still under the influence of a chilly upper-level low leaving to the south of us. Plus a brand new batch of cool air is swinging in tonight through Friday. You can see that 2nd upper low coming down the coastline
This has been the story for about 6 weeks now. Starting around April 9th, we’ve seen lower than normal upper-level heights over our region. In fact, the anomaly is just about the coldest in the entire Northern Hemisphere over the past month! Along with a cold anomaly over the Arctic Ocean.
So one could argue it doesn’t get much colder than this from early April to early May. I just checked the past 30 days at PDX. Coldest since 2011. For the locals, this is running quite similar to other cold springs like 2008, 2002, & 1996.
How about measuring our spring another way? Number of 70 degree days at this point in spring (at PDX)
Only 4 days at/above 70 degrees. That’s quite a change from the past few years. The average is around 9 days by May 10th. Again, this is similar to 2011, 2010, 2003, & 2002. In the last 10 springs, we’ve hit 80 degrees by May 10th, but not this year. We’ve only hit 75 twice. In a typical spring we see more up/down with chilly troughing followed by warm upper-level ridging.
I think the screaming message here is that WE WERE DUE FOR A CHILLY/WET SPRING AND NOW IT’S HERE. There’s nothing especially “unusual” about this spring. No, it’s not caused by climate change. And we’re not seeing any significant trends with temperature or precipitation in springtime west of the Cascades. Obviously summers are turning much warmer but that’s a different story. As mentioned in a previous post, in general springs have been just a little wetter compared to many decades back in time.
More of the same folks! A cold front moves inland Thursday with another .25-.50″ rain west of the Cascades, then a 2nd (weaker) system comes inland Friday night and Saturday morning. So we’ve got a soaker ahead Thursday morning, then much better by evening between those systems. Behind that 2nd system, a warmer southwesterly flow (no cold upper low!) pushes temperatures up around normal for the weekend. No, I don’t see a warm and sunny weekend, but at least the showers will be warmer and we COULD make it into the lower 70s Sunday IF the showers are widely scattered. So clearly Sunday is the better day of the weekend.
By the middle of next week models agree that another cool trough drops into the region, keeping us cooler than normal through all of next work week.
Many times I’d look a bit farther ahead (beyond 10 days), but the past month we’ve seen models regularly push us back into climatologically normal (warmer) pattern. And each time a cold upper-trough decides to crash the party. For now I think it’s safe to say:
- We’ll see below normal temps through at least the 20th of the month
- There’s no sign of a sustained dry spell for at least the next 10 days.
I won’t be staining my decks for quite awhile...
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