February 11, 2015

What was the mysterious dust raining down in eastern Washington?

I love a good weather mystery.

On Friday, I started to get emails and calls about a strange white/gray powder that was being deposited on cars and windows over southeastern Washington and northeastern Oregon.

The picture below is the kind of material we are talking about.    Good for car wash businesses, but roughly a .001 on the meteorological Richter scale.  I put it aside.

The media started having a field day and speculations went wild, many certified by "scientists."

So the possibilities included:

1..   Volcanic dust from Russia
2.     Dust from a Nevada dust storm
3.     Ash from last summer's fires
4.     Dust from the Middle East
5.    Dust from dry lake beds in Oregon

and more.

First, where did folks observe a white/grey powder Friday morning?  Here is a summary produced by the meteorologists at the Spokane office of the National Weather Service.  Southeast Washington and northeast Oregon.

Some of the possibilities were easy to reject.  The dust from the Middle East and volcanic dust from Russian volcanoes didn't make sense, since why would the dust be so localized?   The dust storm in Nevada was promising until I looked at the wind field, which would blow material too far east to reach SE Washington.

Then there was the theory, proposed on the NWS Spokane blog, that the material was blown from the alkali dust field around Summer Lake in southeast Oregon (see red marker on map below for location).

Here is a picture of the lake I found on the web.  And you say a large dusty area on the satellite picture above.

To raise a lot of dust would require strong winds around the dry lake bed.   So I found the winds at the Summer Lake RAWS observing site and plotted them for the Thurs to Saturday period (see below, second panel).    Big winds, gusting to over 65 mph!    More than strong enough to lift loads of dust.

 I wanted to check out the origin of these winds, so I looked at the 18 hr WRF model surface wind gust forecast for 10 PM Thursday night.  If you look closely you will see strong winds (gusts to 55 knots) in the right place--winds associated with strong downslope flow off the Siskiyou/Klamath mountains.

  My final evaluation is to determine the air trajectories that ended up, at say Walla Walla, in the dust zone.  To do so, I ran the NOAA Hysplit trajectory model using the 12-km NWS NAM model for the 3D wind fields.  Lo and behold the air came from EXACTLY the right region...around Summer Lake.

Why is Summer Lake a source of dust this winter and not most winters?  Could it be that this winter has been usually dry and warm?  Here is the percent of average precipitation for the last month.  The summer lake are is has received 25-50% of normal precipitation.

And here is the departure of temperature from normal. Way warm, perhaps 6-9F above normal.   Start with very low precipitation and add much warmer than normal temperatures (which encourages evaporation)--what do you get?  A much drier than normal surface.

Anyway, the NWS Spokane folks deserve credit for suggesting this solution and I basically have just provided a bit of supporting evidence.   There are, of course, some other possibilities, like aliens and chemtrails, but I suspect the Summer Lake  (and similar nearby lake) origin is the right one.


The Pacific Northwest Weather Workshop

Interested in attending the big local weather workshop of the region?  The Pacific Northwest Weather Workshop will be held in Seattle at the NOAA facility on February 27-28th.   Everyone is invited and the majority of talks are accessible to laypeople.  To attend you have to register or they won't let you in the gate.  There will be a major session on the Oso landslide.  There is a registration fee that covers refreshments and food, and special student pricing.  If interested, check out this website.

Climate Change and the Pacific Northwest

I will be giving a provocative talk on this subject on March 11th at 7:30 PM Kane Hall on the UW campus in Seattle.  Sponsored by local public radio station KPLU, tickets for this event can be secured at this web site.


  1. Cliff, an excellent display of scientific reasoning! Perhaps if more understood logic and problem solving, we could get somewhere on policy. "[W]hat it means to study something scientifically... [a]bout 20% of Americans were scored as correctly answering" (http://www.nsf.gov/statistics/seind14/index.cfm/chapter-7/c7s2.htm#s2)

  2. Very cool to hear a reasonable explanation here, I was waiting for your take. Small quibble though, as a Spokane native transplanted to the Puget Sound area, Spokane is not in SE Washington (and the Idaho locations are N. Idaho ). You can pretty much draw a straight line across the state to Seattle from Spokane and I have never heard anyone 'round here call Seattle SW Washington, same difference if you go east. No big deal, EWAs are used to not being understood by the dominant third of the state. Thanks again for your explanation that goes beyond idle speculation.

  3. NIce piece of analysis. If correct, here's something to add into the mix: the problem of blowing clouds of alkali dust around Summer Lake has become much worse due to actions taken by the State of Oregon. Fresh water normally flows into the lake from the north. In a typical winter much of the lake bed would be covered with shallow water. However, "sportsmen" complained that they couldn't get close enough to migrating waterfowl to shoot them, so the state diverted much of the flow into diked impoundments at the north end of the lake. Combine this with low rainfall, and we have a dry lake bed in the middle of the wet season, and a local environmental problem becomes a regional one.

  4. Love your blog! Thanks for the insight as usual.

    I'm am curious though, what is your take on the phenomenon of geo-engineering, i.e. chemtrails? I've been a weather geek my whole life, so I'm not an amateur when it comes to observing the skies or about knowing how contrails form.

    I don't think the grey/white milky rain has anything to do with the so-called chemtrails, but would like to hear what you think about the subject matter overall.

    Thanks again!

  5. I walked out of my office on Red Mountain at 11am that day (W of Tri-Cities) and my truck was covered with the stuff. Never seen anything like it in 17 years here. First thought was a volcano. Second was local farming type stuff. Local radio news was talking about it by 1pm. The stuff was hit or miss across the region based on my non-scientific observations that day. Shouldn't it be uniform on some level coming from that distance?

  6. Spot on job. Interestingly enough, such a phenomenon has been documented before, in other nations including South Africa and Iran, and here in North America, and it's always been tied to drying desert lake beds (playas). We documented a very well known case where dust from Willcox Playa in Arizona caused milky rain in SW New Mexico in January 2008 ( http://bit.ly/1DlVsrR ). Residents in the mountains of Ruidoso and Cloudcroft, New Mexico regularly report a similar phenomenon where dust from the White Sands of New Mexico mixes with the rain: it's basically a yearly event up there.

  7. Great line of reasoning! Seems like some mineralogy studies comparing dust samples from the lake bed and from the affected areas would confirm the analysis.
    Thanks for your blog.

  8. I love Summer Lake. It's what remains of a much bigger prehistoric lake that once covered a much bigger area including what's now both Summer Lake and Abert Lake about 20 miles east of there.

    The water level in both lakes varies a lot. Even when "full," they are salty and too alkali to swim in. I've been through there in the late summer when dust was blowing, and it doesn't greatly surprise me that it made its way up here on the south wind, or that it's to dry.

    The climate history of south central and southeast Oregon, even in recent times, i.e. the 1800s until now, is (to me, anyway) pretty amazing. In the '20s and '30s, Abert Lake went dry, and I suspect Summer Lake did too given that even in "normal" times it's smaller and shallower than Abert. When Abert went dry, the receding water exposed a pioneer wagon, complete with the skeleton of a girl who, after examination, was thought to have been killed by Indians.

    The relevance here is that Abert Lake had been dry when the pioneers came through in the mid-1800s. Then it filled up. Then it went dry. Then it filled up again. In the last few years, it's been drying up again. This part of Oregon regularly goes through climatic cycles that last a decade or two. In dry periods, those lakes disappear, and so do some of the rivers. Groundwater tables drop, making irrigation difficult or impossible.

    All of these changes have happened since the mid-1800s, but before carbon-intensive industrialization. Temperatures and rainfall in that region are phenomenally and naturally variable over short, medium, and long time scales. A lengthy period of abundant moisture lured settlers around the turn of the 20th century, only to have the cycle turn and almost everyone leave.

    I visited for the first time in mid June 2011. The spring was so wet and cold summer arrived a month and a half late. The Silvies River (the biggie in that area) was so high that people were worried about levees being topped and fields being flooded and roads washed out. The following year, it was so dry that 600,000 acres of Malheur County and northern Nevada caught fire and burned, forcing the cattle ranchers in the region to import hay from other parts of the West.

    Drought has persisted since then. Last summer, another 300,000 acres burned on Harney County. In 2013, we were there in September when it was 105 degrees, and again in December when it hit -30 in Burns, Oregon. That was a record for the date we were there, but not a record for the season or for Oregon.

    This part of the high desert has a storied history of Indian wars and larger-than-life cattle barons. Climate and its volatility has played a prominent role in that history, both in modern times and before the pioneer settlement. Wet-dry cycles, and the change of lake boundaries they caused, triggered epic battles between homesteaders and cattle barons, the most famous being the murder of Peter French, the region's most prominent cattle baron who controlled hundreds of thousands of acres, on the day after Christmas 1897. French's killer, a jealous homesteader who French had evicted, was acquitted by a homesteader-dominated jury on the laughable grounds of "self defense."

    There's a town just east of Summer Lake called Paisley. Only 200 or so people live there now, but back in the day (1880 - 1930 or so), Paisley was a notoriously rowdy town where cowboys went for a whore, a fight, a bottle of whisky, and sometimes all three. Today, Paisley is quiet, surrounded by the largest ranch in the United States -- 1 million acres owned by J.R. Simplot, the Idaho billionaire made rich by selling unblemished potatoes that McDonald's made into french fries.

    It's easy to drive through this area and be completely bored. Or to be totally fascinated. Want to guess which category I fall into?


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