A La Nina Winter for the PNW

The Pacific Northwest has a reputation for being rainy, but this fall has been exceptionally so. It’s possible that I’m just unused to it after being in California for a year, but actually….

…we’ve gotten a lot of rain this fall. Based on historical averages, according to usclimatedata.com, Portland gets 1.47 inches of rain in September and 3.00 inches of rain in October. Weather.gov’s data shows that we got 3.76 inches of rain in September – that’s more than twice as much as normal!

October has settled down a bit. As of the 23rd, we have had 2.04 inches of rain so we’re pretty much on track with the average this month. However, there is a storm off the west coast, which could bring more rain tonight and tomorrow – they’re calling it a “bomb cyclone” meets an “atmospheric river.” I don’t know exactly what those things are, but they don’t sound good.

The weather forecasters are saying we are in for another “La Nina winter.” What does that mean? Well, due to sea surface temperature anomalies at the equator (and complex weather patterns that I don’t understand) the Pacific Northwest gets lots of wet, stormy weather in La Nina years.

Image from: climate.gov

(We also had a La Nina year last year. Unlike what I remember from elementary school, La Nina and El Nino years do not alternate year to year. They fluctuate on a 3-6 year cycle, roughly.)

This is good news for skiers (lots of snow on the mountains), and also good news for our water reservoirs. Unfortunately, there’s a big risk that we could have flash floods, especially with the recent forest fires leaving behind dry, bare, hard dirt. And, of course, what does this mean for the garden?

Rot, fungal diseases, and freezing temperatures are a concern. I’m feel pretty prepared for cold weather with the two cold frames we have, but I’m worried about drainage. A lot of our soil is clay and does not drain well. I am worried about the dahlias, since those won’t be under a cold frame. I could dig the tubers up, but I generally don’t have much success with that (the tubers tend to rot in storage). I’ve had better luck just leaving the tubers in the ground. I need to be sure to pile a thick layer of mulch around the crowns though.

I’m especially glad we’ve decided not to plant the olive tree in the ground this year. A La Nina year would be rough on a tree that likes warm, dry conditions.

Stay dry, little guy!

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