July 24, 2015

Finally! Arid Western Washington Gets Relief

It is strange to say this, but it seems strange to see rain reaching western Washington.

Stranger yet, it will be occurring during the climatologically driest period of the year (see plot below of average daily rainfall, which shows the dip to a minimum during this time)

The last month or so has been startling dry.   Here is the plot of the observed and climatological rainfall at Seattle Tacoma Airport since June 5th.  A few hundredths of an inch in June--we are down by roughly 2 inches. A trace (less than .01 inch) in July.   Sahara in Seattle.

Fortunately, the latest radar image (below) is reason for joy for many parched Northwesteners, folks that have had moisture envy of our brethren down in southern CA, of all places.  And it will be a potent tool for those fighting local wildfires.  Associated with an approaching Pacific front, moderate rain is now falling over the NE Olympics and southern Vancouver Is.  It is raining in Vancouver (see cam below).

Today, this front will slowly move through the region, reaching Seattle this afternoon and tonight.   Here is the predicted 24h precipitation totals ending 5 AM Saturday. SW British Columbia, the Olympics and the northern Cascades get the most--roughy a half inch.  The Puget Sound area will only get some light rain later today....not that much (see more detailed map below)

But this is just the appetizer.  On Saturday, a weak upper-level disturbance will move though, bringing light showers (see 24h precip ending 5 AM Sunday).  More over the southern Cascades.

The main event will be on Sunday as a robust upper level trough pushes into us (see upper air map for Sunday AM).   Goodbye big ridge of high pressure.

And here is the 24- precipitation ending 5 AM Monday (both wide and close-in view).  Extensive light rain, with particularly heavy amounts in the north Cascades and Olympics.

For most, this will not be a big rain event...but nearly all in the mountains and west of the Cascade crest will get some light rain.. Temperatures will drop back to the mid 60s to low 70s over the weekend.

The only problem?   There could be lightning on Sunday.  And guess what...the pesky ridge comes back quickly...pushing us back into the 80s and into dry conditions.


  1. Raining steady in Sequim and it is welcome indeed.

  2. Thanks, Cliff.

    But I am rather shocked that you have ignored, or forgotten, the absolute lack of rain in Western Washington since May the first. Not even an inch of rain on the west side of the Cascades in the Puget Sound area in May. Not even close. That really set the stage to our drought here in the Seattle area.


  3. Thinking along the same lines as Rod. Not only has the last "month or so" been startlingly dry; the notable lack of rain stretches back much further. Here in north Whatcom County, I moved into a new home at the start of April. Until today, the number of days with noticeable rain totaled two. Yep, you read that right: two genuinely rainy days. Add to that two more days of showers/drizzle, for a grand total of four days with measurable precipitation. Remarkable.

  4. Finally slept well last night, to the sounds of our beautiful rain....

  5. Rod - where have you been - look back in Cliff's posts and you will see much information and discussion about spring precipitation conditions - every post can't cover the whole spectrum and it is incumbent on the reader to make an effort.

  6. Mike:

    I have been in West Seattle. I read every entry in Dr. Mass' wonderful blog. I feel that the rain, or lack thereof, in WESTERN WASHINGTON in MAY has been UNDERSTATED by Dr. Mass. He mentioned the plentiful rain in EASTERN WASHINGTON in May...

    Michael: I suggest you re-read the great posts by Dr. Mass. Please. Then say: "Sorry, Rod. I will donate five bucks to the Mike Huckabee campaign for scientific excellence".


  7. Wow, what a delightful weekend this has been! I LOVE wearing fleece in July (and I'm not being sarcastic, either). I'm sure we'll be back to the sun sun sun hot slog soon enough but everything has heaved a bit of a sigh of relief the past few days.

  8. The Cliff Mass Weather Blog is one of my favorite blogs. I have read every posting for several years. I appreciate his knowledge and expertise. I even value his opinions on the Seattle School Board, the proper math curriculum in public schools, and vote accordingly.


  9. FYI Monday, 10:02 PDT Walla Walla, Steady showers last twenty minutes. Don't know of Blue Creek Fire. cv

  10. Monday, Walla Walla 10:00 Steady rain twenty minutes past, continues.

  11. I got 1.24 inches of rain in the gauge for the whole weekend on the Bothell Mill Creek line.

    But essentially none- and no lightning- in the Chelan-Sawtooth Mountains, where we camped 2 nights above 7,000 feet.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

Is Global Warming Causing Aircraft Turbulence to Increase?

 After the turbulence encounter by a Singapore Airlines aircraft,  there has been a slew of articles claiming that severe turbulence inciden...