September 06, 2013

Impressive Rain Totals

The worst is over now and lightning has ceased over the region....but precipitation is not over as bands of light to moderate rain circle around the low center position over central Washington.

First, the latest (7:34 AM) radar images shows modest precipitation bands over western Washington, with the heaviest amounts over the sodden SW portion of the state.  Actually dry in Seattle and in much of eastern WA.

 The 24-h precipitation totals for SW Washington are impressive (see figure)  with Lewis and Thurston counties getting hard hit.  An amazing 8.46 inches at the Kosmos RAWS site.  But plenty of locations got 3-5 inches.   The forecast models were right on target.

 Seattle Rainwatch also documented the storm over central Puget Sound, with 1-2 inches over the city and far higher amounts south of Tacoma.  Olympia and eastward got 3-5 inches. 

 Showers will continue today, but nothing like yesterday and Saturday will see an improving trend.  Sunday onward should see the return of sun and warmth as high pressure builds over the eastern Pacific.

This event was an extraordinary success for weather modeling technology and particularly for the NOAA High Resolution Rapid Refresh  (HRRR) system, which provided  extraordinarily useful 0-15 hr predictions.  A frustration for many of us is that HRRR is not operational or always available because of lack of computer power in the National Weather Service.  Hopefully, when the big new computer becomes available in a year things will change.

Amazing picture last night from Alki, looking back at Seattle.  Courtesy of Rod Hoekstra

Announcement:  My Public Lecture Series on NW Weather

I am giving a five-lecture evening short course: "Reading the Northwest Sky: Understanding Our Weather and Climate"  

October 1, October 22, November 5, November 26, December 3  
Kane Hall: University of Washington  
Co-Presented by University of Washington Alumni Association   and Seattle Public Lectures.

If anyone is interested, more information here.


  1. What time of day will the lectures be held at?

  2. Hi Cliff,

    Thanks for the Nowcasting and the rest of your work on this fascinating blog--it is truly a jewel of the web.

    Our family had a question about this most recent storm--why so much lightening? If I understand the mechanics of lightening correctly, it happens when there are extreme updrafts or downdrafts of air, causing an accumulation of static electricity that lightening discharges.

    If that was the case with this storm, then why didn't we see any of the usual things that go with thunderstorms--windy conditions and temperature changes? Or maybe we just slept through that part....


  3. Thursday night I got to watch a great thunderstorm over Whidbey. I was en route to the Wooden Boat Festival in Port Townsend and I had anchored my sailboat between Foulweather Bluff and Point No Point. There was quite a lightning show between about 9 PM and 11:00 or so. Interestingly I did not see where the storm was centered and did not hear much thunder except for a tremondous BOOM following a flash of lightning over me later that night.

    My rainfall total on the Bothell- Mill creek line for Thursday and Friday combined was 1.88 inches.



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