November 13, 2015

Flooding and Heavy Rain

Extraordinary precipitation amounts are now falling on the southwest slopes of the Olympics as well as the north Cascades.

The 24-h precipitation totals (ending 5 AM Friday) show over nine inches at one SW Olympics location and around six at nearby stations.  One research rain gauge has received over 11 inches. The Olympics are getting hammered.  The North Cascades have peaks around 3 inches so far.

The storm total from the Langley Hill radar near Hoquiam paints out the localized maximum precipitation on the lower windward slopes and the extraordinary lack of rain offshore.  You can see why the new radar is so valuable.

The regional radar shows the same thing....offshore the rain is not impressive.  And a distinct rain shadow is apparent northeast of the Olympics.

 This is a good example of a major characteristic of many atmospheric rivers.   This moist airflow does not produce heavy amounts offshore but release their moisture as the air ascends our terrain.

The OLYMPEX experiment is going on now and there is a huge armada of observation assets in place, including research aircraft that are flying this morning.  We will gain huge insights into precipitation processes over this terrain feature during the next month.

There is going to be serious flooding on western Washington rivers, particularly those draining off the Olympics and north/central Cascades.   The latest Northwest River Forecast Center maps shows their forecasts (see one below).  Several rivers will hit moderate flood stage (blue dots).  Don't even think about driving through flood waters...can be a fatal mistake.

And big news....looks like lots of snow in the mountains on Sunday....more later.

I will talk more about this situation on KPLU FM (and streaming) at 9 AM in my usual segment with Bellamy Pailthorp.


  1. What about the snow? Looks like rain next week too

    1. Yep, what about the snow is right. All of the feet and feet of snow predicted for the Cascades looks like it will be rain after all. Si much for everyone skiing by Thanksgiving. Maybe next year.

  2. Cliff, your post is a good one, and informatively interesting, but it also reminds me of two things that happened this morning, and happen frequently.

    When I'm out putting up our bird feeders in this morning I also check my rain gauge. This morning it had just over 1/2 inch in it; yesterday just 1/4 inch. But on the back of Section B in the Seattle Times I see that the Weather Bureau reported just a scant 0.6 inch of rain. This happens frequently.

    Granted, I'm in NE Seattle, about 2 miles from U of W, and granted my wildly inaccurate rain measurement system isn't a standard for Seattle, but the discrepancy seems notably large, regardless. The rain season won't care; the reservoirs get what they get and the snow pack accumulates what it gathers. But how reliable are official weather records, especially in rain events like those we've had this Fall that rendered similar noticeable variances, if my anecdotal observations are somewhat, or, especially, mostly accurate?


  3. Hi Cliff, I heard this morning that KUOW is acquiring KPLU for something like $8M and turning it into a jazz only station. Will your much loved segment die or move back to KUOW?

  4. This is sad news. While I used to listen to KUOW, they went downhill and I switched completely to KPLU. I have supported KPLU with my donations since then. If they do not improve and keep the better KPLU coverage, then I am unlikely to continue to listen to and support them.

  5. John McBride, you may be confusing yourself with the whole fractions v. decimals thing. If you emptied your rain gauge between the aforementioned readings, your cumulative total of 3/4" would only be off by 0.15" from the total reported in the paper. If you didn't empty between, it would only be a measly tenth of an inch off.

  6. Was headed to the resort at the Quilute. They called and said the road was closed until further notice. Check roads before attempting to head to the coast. We're going to miss this storm :(.

  7. I also wondered about the KPLU-KUOW situation.

  8. I haven't checked other ski areas, but the latest forecast for Stevens Pass predicts temperatures a couple degrees higher than yesterday's forecast, and most of the base-area elevation precipitation falling as rain. Boo.

    @ John McBride - Precipitation can vary wildly, especially in a region with complex topography like ours, even across a small distance like the 2 miles between you UW.

    Similarly, I had a recent trip home from work where I drove through an intense thunderstorm that I passed out of less than a mile from home. When I got home, I was surprised to see the pavement in front of my house still dry. I assumed I'd driven ahead of the storm and waited for it to catch back up. And waited. It never came. For whatever reason, the clouds just north of us where I was driving had decided to open up and dump. The clouds over my house kept their rain for somewhere else.

    However, even though the official gauge may see a different amount of rain than what fell on your house, it's still useful information for general ballparks (If they got an inch, it's more likely that you also got heavy rain than if they got 1/10 inch), and for comparing trends over time.

    I also live a few miles from the nearest official gauge and am pretty certain I consistently get more rain than the official gauge does. I just bought myself a gauge so I can start testing this theory.

  9. Looks like snow levels could creep down to sea level using this handy site...

  10. @ John McBride - You can see examples of how much rain can vary from location to location here:


    Interesting website that explains some new weather equipment being places on the Olympic Peninsula.


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

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