August 10, 2013


Last night brought substantial lightning, thunder, and showers as a band of convection moved northward across Washington.  As I will discuss later, these thunderstorms are associated with a upper level low that is moving northward across the Northwest this weekend.

The thunderstorms hit the Puget Sound area around 1:30 is a nice radar image at 1:57 AM Saturday.  You see a line of heavy showers (reds/oranges), with lighter precipitation (green) following behind.
Here is a wonderful picture of the lightning taken over downtown Seattle by Rod Hoekstra.

There was lots of lightning over eastern Washington and unfortunately some ignited new fires (as warned by the National Weather Service).   Here is a picture (by Draysen Brooks Bechard)  of a new fire near Wenatchee.

Tonight may see a repeat.   Take a look at the upper level forecast map (at 500 hPa, around 18,000 ft) at 5 PM Saturday.  You can see an upper level low over Oregon and a lobe of low pressure, just south of the Oregon/Washington border, that is rotating around it.  Those lobes are associated with upward motion that can force new thunderstorms.

In fact, the latest visible satellite imagery at around 3 PM shows thunderstorms building over eastern Washington, as does the radar (see images).

One of the most useful forecasting tools over the next 6-12 hours in the NOAA/NWS High Resolution Rapid Refresh (HRRR) modeling system.  Here is the forecasting for 11 PM Saturday of a simulated radar image.  You will see a band of thunderstorms moving north across Washington, really reminiscent of last be prepared for more thunder!

The low will move northward on Sunday and the weather should calm down with a return to typical (and dry) midsummer conditions.

Update at 5:30 PM Saturday: lighting is widespread over northern Oregon and in a strong cell over the central Washington Cascades.
 10 PM update:  Lots of thunderstorms in a line from eastern Washington to the central Cascades (see radar).

Lightning network data (for hour ending 9:20 PM) shows many hits.
 Rain will be moving into western Washington now...


  1. Awesome Cliff. Thanks so much. My young kids are fascinated with thunderstorms and we've been watching the radar and then looking out at the incoming cumulonimbus all afternoon. A friend recommended your blog and you didn't disappoint. :)

  2. What a great resource this blog has been, since the rest of the weather-industrial complex rarely gives us in-depth weather analysis and forecasting. I only wish you would have warned us about these T-storms yesterday, so we could have moved the Shih Tzu out of the way of the thunder boomers. Tonight will be different, as we are heading for Pullman. Hope conditions are better there!

  3. Cliff, as always, spot on with your blog. I live 3 miles NNE of Monroe and we had some house shaking thunder. I woke up at 1:30 a.m. last night and literally thought there was an earthquake (from the thunder) until I saw another flash - only about 20 seconds later. It was a great show!

    Is there a good place to see a lightning stroke map? Thanks!

  4. My wife and I were staying in a cabin near the Miller River all of last week. There's no electricity no water and at 6 miles from the nearest town, no cell nor wi-fi. Imagine our surprise at about 10:00 pm Friday to see what appeared to be a nearly uninterrupted giant strobe show behind the central Cascades south-southeast and southeast of us. Yet the sky above us was full of stars.

    We went to bed about 11:00 with only my conjecture that it was distant lightening to explain what we were watching,although in 45 years of hiking and climbing I've never seen the likes of it.

    At 12:00 we were awakened by a torrential downpour, thunder and lightening. Before there had been not even distant thunder. This time it was unmistakable and right on top of us.

    Very impressive show overall. Zeus and Thor were having some fun fest. Must have been over a hundred cloud-to-to-cloud strikes before we went to bed.

    Too bad about the fires. I presumed as much but hoped that as where we were there would be rain to extinguish it.

    We can hope this is one of natures beneficial fires.

  5. The new fire is near where the colockum tarps fire started.

    Last night was insane. A tree was blown over in Quincy, power lines were down in a few areas, some phones lines were out for awhile.

    The cloud to ground lightning was pretty impressive. We saw one hit a power pole (nice secondary green flash after it hit).

    That storm was severe warned after it left us, but I am pretty sure it was severe while it was over us. Pea sized hail, wind blowing like crazy. I estimate the gusts were at least 50 mph, and that's a conservative guess. Roads were flooded with 2 feet of standing water. I've never seen birds hide on the ground until last night.

    I opened windows in my house, and right before the wind and rain unleashed, the curtains were all being sucked OUT of the windows, against the screens. It was the weirdest thing to see.

    I was really thankful for the rain, it was so hot and still all day. The storm dropped the temperature fast and cooled the house down.

    Also, usually we can hear the thunder quite a ways off. Last night, as we stood in the yard watching it come from the south, we didnt hear it. We only heard it when it was over us and after it passed north. That was also odd.

  6. Hi Cliff,

    Up in Bothell there was just a relatively mild storm Friday night. Even the convergence zone where I live just didn't really deliver the show like the Cascades, I guess. Well, maybe the convergence zone is irrelevant with flow from the East.


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