September 12, 2017

The Northwest's Summer Drought Will End on Sunday

It has been an amazingly dry late summer, with very little rain during a period when showers typically return.

If you want to be impressed, here is the cumulative precipitation at Sea-Tac Airport for the last 6 months that actually occurred (purple) and which is normal (blue).   You might be startled to note that the precipitation for the past 6 months has actually been ABOVE normal, but that was due to an unusually wet spring.  For most of the warm season (since approximately 15 June), Seattle's precipitation has been essentially flatlined.  Earlier in the summer (before late August) this is not that unusual, but having nothing for the first half of Sept. is not a common occurrence.

Dry conditions will continue through Saturday, so enjoy the nice weather while you can.  Here is the cumulative precipitation for the entire country from the NWS GFS model through 11 AM Sunday.  Washington is pretty much dry.

But later on the day on Sunday, the first substantial frontal system will come that will provide a real wetting-down of the region.  The 24-h precipitation ending 5 AM Monday provides the story, with 1-2 inches in the mountains and light rain east of the Cascade crest.  This event will provide substantial aid for reducing the wildfires that are still burning in our region.

The cooler weather of late has restrained the regional fires-- as shown by the MODIS satellite imagery yesterday, many of the fires are still burning, with local smoke.  But the huge plumes of the past few weeks are not apparent.

 The excellent forecasts for Seattle (partially based on National Weather Service models),  show that the really warm temperatures  (85F and more) are history for us, with 70s and then 60sF in our future.  The sun's radiation is rapidly weakening now as the day's shorten---and the atmosphere is finally responding.


  1. oh well, the fun has to end sometime. it's been a great summer! hopefully we have some more nice sunny days in our future.

    now where's my caulk gun???

  2. Let is rejoice and make merry. Moisture is returning to the Pac NW

  3. The lack of August precipitation obviously put the double whammy on the Gorge, as the resultant widespread fires can attest. All it took was one stupid teenager throwing a bunch of lit firecrackers down one steeply wooded hillside, and...poof. I hope that more attention will be made on the massive build up of fuels all across the PNW over the past six decades, due to strenuous fire suppression efforts and the lack of the culling of trees from Forest Service properties. It has left the region vastly more vulnerable to these kinds of fires in the future, and it doesn't matter whether AGW is a contributing factor or not - the current predicament would still be the same.

  4. It seems to me that the dry part of the summer is indeed getting longer, Cliff, but you indicated that the spring would get cloudier (not my favorite scenario) under global warming. Historically, about one out of every three or four of my hiking weekends would be washed out- even in summer. But not in the past few years. How does the longer, drier summer scenario reconcile with the cloudier spring- does it mean that the "June gloom" will become "May Gloom" and June through September will be the new, longer dry period?

  5. Thank you for making this rain possible, Cliff.

  6. What was fun this morning in Sequim on Bell Hill was waking up to light rain. Nothing in the forecast. Nothing even on radar. But 0.04 inches of sprinkling to far, and it continues.

    Must be an upslope from stratus lifting off the Strait (we're at 1000' elevation and in the clouds). Whatever it is, it's wonderful to see every tree and blade of grass wet and glistening this morning, with small puddles in the driveway.

    Small potatoes compared to winter, but wonderful after this long dry, hot summer. I look forward to more of the same this coming weekend.

    Now that I've been painfully reminded by how brown, dry and crunchy my property and trees can become in such a long, hot summer drought, with many trees struggling and stressed, I promise not to complain about the rain this winter. Trees are my thing, and this has not been a good summer for them, despite my spending a fortune on irrigation.

  7. I'd like hear more about Sunday's front and how it could affect the fires in the east Cascades and Gorge. Will it punch through enough to slow the fires or allow containment?

  8. A simple exercise would be in order: Compare the fire experience in private forests, which depend on income from timber sales, with the fire experience in public forests, which have been "protected" from rational management.

    Oh, but wait! That would entail factual analysis, and the "progressive" "environmentalists" who have gradually insinuated themselves into the Forest Service would find themselves embarrassed by the results of their long-term incompetence.

    It's Seattle, and "progressives" are in favor of evidence, as long as they can determine what "evidence" might be.

  9. Joe - what I don't like is traveling to places like San Diego and not seeing the stands of Douglas Fir and Western Red Cedar trees everywhere, like we have up here. You know if there were more fir and cedar trees down there, I'd sure like San Diego a lot more.

  10. @Placeholder - In that fires know no boundary between private and public land, and are free to jump from one to another, and that any "comparison" would involve acreage burned, the "factual analysis" you seek is always going to be potentially unreliable.

  11. Placeholder, what negligence? They do what they can with what they have. I'm sure there's a lot they would like to do but can't.

    You're so negative, how did the environment make you so mad? What's wrong if people want to protect it?

  12. Placeholder,

    A simple exercise would be in order: Compare the recreational and tourism dollars for government and private businesses generated from public lands, along with the value to the public for enjoying those, with the recreational and logging dollars generated in "private" forests.

    Oh, but wait! That would entail suspending factual understanding, and thinking that the gorge = monoculture tree farms in foothills by Chehalis. I mean, do you frequently go to some state lands that are on clear-cut rotation north of Morton in lieu of going to Goat Rocks or the Enchantments because it is just as scenic?

    I have heard a lot of "educated" people letting us know the solution to forest fires is to cut the forest down. The logic is air tight!

  13. I think I can sum up placeholder's view:

    If we let the timber companies cut down all the trees there won't be forest fires.

    Easy peasy!

  14. Looking back now, take away those two weeks of smokey heatwaves (early August, early September) and it was a very nice summer. But I am ready for cool temps and the rain.

  15. I think I can sum up joe mama's view:

    "I'm a Seattle 'progressive.' I don't actually know anything, and more to the point I really don't want to know anything. That's because I know everything, even though I don't know a thing, because smugness is everything."

    Re-elect Ed Murray! Perfect for Seattle.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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