2011 Weather Year in Review

Well I’m really in trouble now. I have about 90 things I want to post about and I haven’t touched the blog in a month. First there was the snow. That was quite a distraction. We got out and had fun in it when I wasn’t knocking snow off greenhouses or anxiously watching how cold it was getting in Whatcom County. Fortunately those 6° temperatures failed to cross the water this time and it didn’t get any colder than 24°F here in Sequim. Now it’s sunny and mild, and all of a sudden there is this sense of panic that winter is almost over and I didn’t finish enough of my projects! I also kind of stopped paying attention to some of the garden blogs I follow: how dare I. But as things seem to be getting back to normal it is time I got with the program here. Especially with so much I want to talk about.

So to start with: having read an excellent “year in review” post over at the Desert Edge, I thought I would steal the idea and try to do something like that here. Of course it will probably come out very different since I tend to just keep on writing and not stop for a long time, and I don’t really have a whole lot of photos to go with this. But in any case I like the idea a lot even if I am four weeks late by now. It will be great if I can make this an annual January tradition but at this point I’ll just shoot for one occurrence. It will be good to have some sort of written record to look back upon of what happened this year.

Starting with temperature, 2011 was cold. Observations suggest that we re-entered the cool phase of Pacific Decadal Oscillation around the year 2007. Pacific Decadal Oscillation (PDO for short) is the name assigned to long-term (20 – 30 year) fluctuations in sea surface temperatures in the northeast Pacific Ocean, which is directly upstream from our weather. You may recall that 2006 had a beautiful warm summer followed by a wild winter with multiple cold events and more rain and wind than usual. Now we seem to be stuck in a pattern of just colder than usual.

So how did the year stack up? Well, it should come as little surprise to anyone who was paying attention that the year was cooler than normal. The year began with one of the strongest La Nina events in history and ended with La Nina still in place, albeit weaker.* It is well known that La Nina, the “cool phase” of sea surface temperatures in the equatorial Pacific, effects our weather to (on average) make it cooler and wetter, especially in late winter and spring. Sea-Tac airport, often used by climatologists to represent the whole region (I’m not sure why, but I guess I’ll go with it), registered an average high temperature of 58.04 degrees** for 2011. The average annual high temperature is 59.32.** While that may not seem like a huge difference, one must consider that a whole year is a long period of time to maintain a trend in something like weather which is constantly changing.

To put this into perspective, the last time we had a year colder than this was 1985 with 57.53. That year was very different from 2011, however, featuring a hot July and a very cold November and December. By contrast, 2011 was relatively lacking in temperature extremes: summer was cool; winter was cool. It is also worth noting that a close contender for coldest year in recent times was 2008 (58.48 degrees**), also within the transition to the cool phase of PDO. Interestingly, all years from 1986 – 1998, the chronological center of the previous warm phase of PDO, registered at or above our mean annual high temperature**. So if it feels like the weather has been getting cooler than it used to be; well, there are actually statistics to back that up.

So was this year a record? Not even close. But to find all the really cool years one has to go back to the 1950’s and 60’s. This was the chronological center of the previous cool phase of PDO, and most of our record cold years in modern times come from this period. Taking the prize is 1955 with an average high of 55.26 degrees for the year at Sea-Tac.* Can we expect cool weather like this to continue into the future? Quite possibly: it appears that PDO has a very direct effect on our temperatures.

Now having said all that, it may also be worth noting that Sea-Tac might not be the ideal location for comparing a given year with the past, since the third runway has quite likely made Sea-Tac Airport appear warmer than it ought to be: see Cliff Mass’ post about this. Thus, if I had time and really wanted to go in depth, it would be worth taking a look at more weather stations. But right now I don’t: perhaps someday I shall and I can put something about it on the Articles page.

Taking it month by month, we can note that the only months warmer than average at Sea-Tac were January and September, and January not by much.* (August may be reckoned as slightly warmer than average if a 60-year period of record is taken for the average,** but climatologists usually use 30 years.) All other months were cooler than average, and basically only the last half of August and first half of September really felt like summer. The real shocker was April and May. With an average high of just 52.23 degrees, April was in fact the coldest on record, just beating out April 1955.** Coming in with an average high of just 59.74, May was more than 4 degrees below normal, the second coldest since 1962 (curiously, May 1999 was colder),** and the fourth coldest on record. Compare this with average May highs of 70 or better in 1995 and 1992,** and it may be no wonder we’re feeling lousy around here in the spring of late. No, those warm spring days somewhere back in the recesses of your memory weren’t just imagined!

I shall say less about precipitation since nothing really surprising happened. April and May were in the top few wettest on record, but neither was a record. The cool and wet spring got us somewhat ahead of normal for much of the year, but our usual summer dry period arrived right on schedule despite temperatures remaining below average. The oddest thing to happen was three and a half weeks of essentially dry weather in December: following that, we ended the year about an inch below normal; which, I think we can say, is abnormally close to normal.

Perhaps the most noteworthy event of the year was the snow and cold that showed up around the end of February. Here in Sequim the temperature dropped to 16°F and we had 7” of snow. That really wasn’t a big deal since it had already been to 11°F back in November, which was far more destructive to plants. So by February there was nothing left that could be vulnerable. Some people see plant damage following a late freeze and blame “that last hard freeze” even though “it survived the first one.” I grant that sometimes happens, but I think more often the damage is done in the early freeze and just takes a few months and a spell of milder weather to show up.

So how did the plants respond to all that? Well it should come as no surprise that anything that loves heat didn’t have a great year. A large crape myrtle in Port Angeles produced buds but they froze dead in late fall before they had a chance to open. At our house an (inherited) established Magnolia grandiflora that has reliably bloomed every year until now, did not bloom. By the time the heat finally showed up in August, there simply wasn’t enough time left.

For the nursery here it was no big deal. If anything a long cool spring gives me more time to pot up plants before they get all overgrown in the warm weather. I find that even if a hot year produces more growth, it really becomes a struggle to stay on top of it: all of a sudden it’s August and I have a zillion little rootbound plants that need potting up. So that didn’t happen so much this year. The only annoying thing was that I put off putting shade cloth on the greenhouse until August, then never did it. The weather was one factor, but I also wanted to have a chance to tighten the greenhouse plastic, which I never could get around to. Finally in August the sun came out and a lot of shade loving plants turned yellow. So, I won’t make that mistake again: always put the shade cloth on, now matter how bad the weather is. Sunny Sequim is still sunny and better late than never.

To make a long story short it seems that plants that are really well adapted here, whether native or not, took this cool summer in stride. I have never been that much into pushing the limits with heat-demanding plants, and a lot of xeric and deserty-looking plants can easily go a couple years without a hot summer: they simply slow down a little bit and/or bloom later. So despite the cool year, and people’s perceptions, the game has not really changed for us.

So… how did your plants and garden respond to the cool weather in 2011? Or, not so cool, if you’re posting from outside the Pacific Northwest. Do tell!

Nursery under snow, February 25, 2011.

Planting stuff in September – a great time to plant!

Magnolia grandiflora flower: it did not bloom this year.

* Source: National Weather Service, Seattle Office.
** Source: Western Regional Climate Center