October 27, 2018

The Spigot Turns On

We can now look back on our dry season as we turn to the wet portion of the year.  As shown in the plot below, which shows the observed (purple) and normal (blue) accumulated precipitation since 1 May at Sea-Tac, we have clearly had a dry summer, receiving about 5.5 inches less than normal.
Looking at nearly the same 6-month period, but with a regional view (see below), shows that western Washington and Oregon had the largest dry anomalies in the western U.S., running about 4-8 inches below normal in the lowlands and even drier on the western slopes of the Cascades.   Arizona, hit by Hurricane Rosa, was a wet spot.

Kind of interesting...if you wanted a dry anomaly...head to western WA.  Wet anomaly.... Arizona.

Well, the dry anomaly is about to disappear.   Here is the total precipitation forecast for the region over the next week, based on the UW WRF forecasts. 2-5 inches over the mountains, with some favored terrain areas (e.g., Olympics, Vancouver Is) getting over 5 inches (red colors).  1-2 inches over Puget Sound.

To get a longer-lead view, here is the latest 384 hr (16 day) total precipitation from the National Weather Service GFS system (see below).  California is dry, but much of western Washington will receive more than 4 inches and the mountains hit by as much as 10-15 inches.  If this verifies, much of the summer deficit will be made up by mid-November and our reservoirs will start filling in a major way.

Finally, it is really pouring around the Northwest on Saturday night...the 7 PM radar image is impressive.  Yellow is heavy rain.

It will rain overnight, with showers and blustery winds tomorrow.  The meteorological faucet had been turned on for the winter.  Enjoy.


  1. Snow geese shouldn’t be too far behind.

  2. I've already seen snow geese on Whidbey Island stating last week.

  3. The whitewater kayaking season has begun! We got our first run of the season on the Tilton River on Sunday. Bring the rains!

  4. my home in Bellingham got 1.35 inches of rain Saturday night -yes we have now entered the wet season.

  5. It is always fun to observe this transition. As a relative newcomer to the area (6 years now), I like to tell outsiders that "Seattle's weather is MUCH better than its reputation", with the caveat "except in November and December."

    Truth be told, though, I kind of like the coziness of being inside, with a fire going, on dark and wet days and nights, sitting in a comfortable chair under a blanket.

    Would be nice if some of these early season rainstorms could drop some snow in the mountains.

  6. Spigot seems to have turned off.


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