climate

The cold return...

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In mid-February there was some small hope that we’d break out of this coldish streak we’ve encountered in Seattle since early December. It turns out this was wishful thinking. There were maybe a week’s worth of slightly warmer-than-normal days to enjoy, but these were accompanied with some heavy rains as well. For a week now, we’ve flipped back to a cooler-than-normal situation. The long-term forecast is much of the same continuing through March. It’s not really that cold; it’s above freezing. But I think a lot of us are looking forward to some more springlike temperatures. I’m pretty sure the plants are.

Daily departures from 30-year normals.
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As I mentioned, we had some heavy rains the first half of February. These nearly matched the heavy rains of last October, before we hit a relatively normal-to-dry period from November through January. For a brief period, it appeared we might catch up with last year’s very wet winter. But the rains seem to have taken a pause now that the cold weather has returned.

Onto March…

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A warm, wet storm arrives. Is this a turn towards spring?

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Early this morning, about 3:30 A.M. a pounding, wet rainstorm woke me up. I sleep beneath a skylight, and though it has yet to leak on me in 17 years, I suspect one day it will. It is in a skylight’s nature to do so. This squall came after an all day rainy Wednesday.

The seasonal water year begins on October 1 in Seattle and runs through the next September 30 for any given period. This year’s water year began exceptionally wet starting about mid-October. Storm after wet storm blew in. But in December — a normally wet month — we seemed to get a reprieve. January was similar except for perhaps a few rainy, individual days.

February seems to have picked up where October left off. We started with snow, but it’s been the strong storms the past few weeks which have really added to the precipitation totals. 

They say more is on the way later this weekend. If true, we may catch up with last year’s very wet winter. But, even with these heavy rains, that would be a tall order.

 

Cumulative Precipitation for Several Seattle Water Years. Seattle is known for rain. But mostly our rains come in the winter half of the year. Therefore, a local meteorological measure of time is the water year, which runs in our region from Oct 1 through Sep 30. The chart above tracks the cumulative amount of this year's water precipitation (blue, dashed line).

The most recent five water year tracks are illustrated in black, with last year's water year track in shown as the heavy black line. The remaining gray tracks are water years for the 2002-03 through 2011-12 seasons.

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The recent rains have been warm. This is shown on the far right end of the chart below. Spring often hits Seattle in late February, with our relatively mild Pacific climate. Maybe the cold snap we recently experienced (highlighted on the chart) is over for good and we’re moving into spring. The daylight sure is stronger and richer.

I hope this is true, but it's too early to tell.

 

Daily Temperature Departures from 30-year (1981-2010) Averages. A significant change occurred in the early part of December where a lengthy, relative warm year switched to a cold period for about two months.

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Continued cold...

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Our coldish winter in the Pacific Northwest continues. About halfway through winter, cooler days than normal days are the dominant pattern. Here in Seattle we received about four inches of snow on Monday. It's not a large amount, even for here, but it is the first significant snowfall we've had in five years.

Starting a few days into December, the mean daily temperatures switched abruptly from warmer than normal for most of 2016 to cooler than normal. Aside from a few days, it has remained consistently cool.

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A wintry white scene in Seattle's Volunteer Park on February 6, 2017.