August 02, 2014

Thunderfest Over Western Washington

As advertised, there is a lot of lightning and thunder around western Washington this morning, particularly over central Puget Sound and the mountains.

We have some fairly unstable air over us....meaning that with a little lift, convection (including thunderstorms) can form.  And we had the lift in the form of a weak upper level disturbance (a short wave trough) moving through this AM.   The images from the UW cam showed the development of the convection (the images run from around 5:30 AM to 9:30 AM.

Most of this convection was high-based and only light rain reached the surface.  Here is a wonderful picture from local meteorologist Mark Stoelinga that beautifully illustrated the mid-level bases of the thunderstorm and the evaporating rain falling out of it:

You can see the convection in the latest visible image (11 AM).  Most impressive storms are over the Cascades. You can also see low stratus along the coast.

The latest NWS/NOAA HRRR (high-resolution rapid refresh) forecast suggests that the southern/central Puget Sound convection should now be dying SeaFair fun should be fine after 1-2 PM.

Yesterday afternoon we had a REAL thunderstorm over the central Cascades that reached 45,000 ft--unusual for our region, which usually experiences wimpy thunderstorms.

Here is the visible satellite picture at 4 PM Friday and the radar echo top product a half-hour earlier from the Camano Is radar.   You see the yellow color--45K feet or higher!

As noted in my earlier blogs, there is a lot of potential for lightning-initiated fires with this short wave passage.  Here is the lightning strikes for a half-hour ending 10 AM...the central Cascades are getting lit up.

Update:  Some of the lightning appears to have taken out power to several thousand Seattle City Light Customers.  Here is the 1 PM map:


  1. I am planning a hike on Bandera, just east of North Bend, for tomorrow morning.

    Should I feel safe doing it, or send out a cancellation?

  2. Great call, Cliff. I see what you mean about the un-stable air and the week trough moving through. You nailed it. Got up early here in West Seattle and saw the high rising clouds. Like a Swiss watch. Rain at 0800 AM.

    Thank you, Cliff.


  3. 0.13" just after 9:30am on saturday in Normandy Park.

    Very localized since SEATAC just 2 miles away only recieved 0.02"

    My Davis Vantage Pro Plus had the rain rate at 3.76" for the brief time it was falling!

    I was in eastern WA, but I watched the doppler as the cell crossed directly over my house.

    I also drove through some of those huge storms as the crossed I-90 near Eaton Saturday afternoon.
    We had some fairly large hail that was mostly melted due to the high bases and warm temps.


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