May 03, 2014

May Inundation

(see update at bottom)

It is POURING outside right now.  Streets are starting to flood. This weekend is going to be an unusually wet one for May.

First, here is the 12-h precipitation ending about 9:45 PM Saturday from Seattle RainWatch.  Some parts of southern Seattle have already gotten 1 to 1.5 inches. Even heavier amounts on the Kitsap.

The wide view shows the large difference between heavy rain in the south and central Sound and the light precipitation in the rain shadow NE of the Olympics. (this figure is based on the Camano Island radar so you can't just the precipitation over the Olympics or over the coast).  This pattern is consistent with southwesterly flow aloft.

Seattle RainWatch not only provides real-time information on rainfall amounts, but it sends out warnings to Seattle personnel and its developers (like Jeff Baars and myself).  Here is what my email looks like tonight:

Take a look at the high-resolution WRF weekend total precipitation forecast (5 AM Saturday through 5 AM Tuesday).  2-5 inches over the mountains and 1-2 inches over the lowlands.  Even eastern Washington gets some real rain.

Guess I won't have to water my vegetable garden tomorrow.

Update: here is the 24h precip total from RainWatch ending 7:30 AM Sunday.  3-4 inches near the Hood Canal  and over 2 inches in parts of SW Seattle.  But only light rain over the NE Olympic Peninsula.
The 24 h precip map from observation sites (available on the Seattle NWS website) shows the serious precipitation SW of the Olympics, with a profound rain shadow over the Strait and San Juan Islands.  .04 inches at Port Angeles and .02 inches on San Juan Island, while Hood Canal had 3.65 inches.  It is nice to live in a place where you can pick your weather.


  1. Yes, but at this rate you just might need a boat to get to it...

  2. Have I noticed, over the past few months, that the coast radar has been out of service? T. Longbranch, WA

  3. coastal radar is working fine....cliff

  4. NE Olympic rain shadow was operating on fine form on this storm. Not enough to make the grass happy where I am in Sequim. Our fruit trees also voted with their blossoms this year and bloomed early. Most have already lost their blossoms.
    Also, one small metric on our winter here...our neighborhood association only used 15% of our usual fund allotment for snow removal this winter. We're on the very top of steep Bell Hill, so we call out the plows whenever its white. Didn't make many calls this winter.

  5. Cliff, can you give us a Mother's Day weekend outlook?

  6. The rain shadow effect over the San Juan Islands had disappeared inland. Much more inundation and I will grow webbed feet.

  7. > so you can't just the
    > precipitation over the
    > Olympics or over the coast

    Text missing there? "just can't see the precipitation over the Olympics" probably?

    Re Sequim, I'd be very curious what climate change is expected to do in that little dry area. An explosion of native cactus? More beetles attacking the trees? Fire danger increased/ fire intensity increased, from lots of dry material that's been damp forever in the past?

  8. >Re Sequim, I'd be very curious what climate change >is expected to do in that little dry area. An >explosion of native cactus? More beetles attacking >the trees? Fire danger increased/ fire intensity >increased, from lots of dry material that's been >damp forever in the past?

    That presumes that climate change will make us drier here. I thought I'd read somewhere that the coastal PNW could get wetter if the Pacific gets warmer? More Pineapple Expresses or whatever.

    It's only the storms from the SW that we get protection from. Weather from NW hits us full, and we're on the upslope on storms from the NE (Fraser River outflows) and therefore get more snow than most on those. Fortunately those are rare events with regard to bringing moisture.

    I'd be curious as to what the latest climate modeling is looking like for our area. More wetness from the SW storms or less?



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