Sunday, July 1, 2018

Darkness Strikes Central Puget Sound

It seems almost like winter yesterday around central Puget Sound... the skies were dark and stayed dark most of the day.   And this is the time of the year when the sun is highest in the sky and the day is longest.

How bad was it?  And why? 

First, how bad.   Quite bad. Here is the solar radiation measurements from the WSU AgWeather network for its northeast Seattle location.  Saturday's value was the lowest since April 14th and is more representative of average values in mid-February.

Same story at the nearby University of Washington solar radiation site.  At Puyallup in the south Sound, the solar radiation was the lowest since mid-March!

 Well, there was clouds--relatively deep clouds.  Here is the visible satellite picture around noon--- an frontal band of right over us

And these clouds were relatively deep, something suggest by the infrared satellite photo (below).  Infrared satellite imagery provides the temperature of the cloud tops and these were relatively cold (and thus high).

There was, in fact, light rain with the front (see radar below), an indicator of the moist lower atmosphere and the depth of the clouds.

The radiosonde sounding at 5 PM (launched at 4 PM) Saturday at Quillayute, on the northern WA coast, showed a completely saturated/cloudy layer in the lower atmosphere, with the temperature (red line) right on top of the dew point (blue dashed line)--that means 100% relative humidity.

And the model simulation of the vertical structure of the relative humidity on the WA coast, showed a very deep layer of saturated conditions (green color) during mid-day (height in pressure, with 700 being about 10,000 ft, time runs forward from right to left, 070100 indicated 5 PM Saturday).

Depressingly, today is not much better than yesterday, with a Puget Sound convergence zone keeping the clouds (and light rain) in place over the central sound (see solar radiation trace at UW below).  I was planning on painting my fence today--the project will be delayed.

But there is one encouraging note.  If you want to escape the murk, the sun is only a short drive away.  Just head across the Cascade crest towards eastern WA.   Just an hour away on I-90 (see visible satellite pictures) and you will be in clear or nearly clear skies.  Sun and  70sF are very close.  Farm stands and desert hikes.

One of the marvels of living here.


  1. Your column validates my experience when I went for a walk yesterday afternoon. It felt like winter!

  2. Feel free to drive over the mountains, as long as you know that it's crawling with rattlesnakes and everyone is armed over here. Welcome!

  3. Used to own a cabin in the hills above Omak. Folks, Placeholder is not joking - I've stared back at both armed rattlesnakes and armed humans over there on more than one occasion.

  4. The rattlesnakes are okay. They only strike if they feel threatened and they'll (almost) always rattle first. Just take your headphones off, pay attention, and give them space.

    Can't always say the same for the two-legged threats.

  5. It deserves mentioning that it's been windy over here on the bright side of the state ;)

  6. Patrick, I'm going to guess you read that somewhere and have never actually encountered one. The rattlesnakes are not "OK" - they are deadly. Our dear dog was killed by a rattlesnake near Riverside. Also, brother's dog - killed by a rattlesnake down in the Sierra foothills.

  7. Rattlers are also common east of the Gorge in Oregon. First time I was in Bend and trying to learn rock climbing, I saw a nest just off the trail one day, and was appropriately scared shi-less.

  8. John K., I have encountered rattlesnakes. My sympathies on the loss of your dog. I don't recommend taking dogs in rattlesnake country.

  9. Pat - thanks for the recommendation. Where do you teach on the subject?

  10. I went over hiking in the Eastern Pasayten Wilderness to climb Remmel Mt. on Sunday afternoon. I'll say the weather was not a whole lot better there. Monday was cloudy with intermittent showers. Same on Tuesday. Only Wednesday was partly sunny. From the summit it looked like the clouds were about evenly spread over the North Cascades. Looked like the famous "Blue hole" was clear. This was Wednesday morning at 9 AM.