May 17, 2016


Well, we had Ridgezilla, the intense area of high pressure that brought low snowpack and warm temperatures last year.  Or the persistent and powerful Godzilla El Nino.  But during the next week we will experience something different:  Troughzilla, an area of intense low pressure over the west coast that will make it cooler and wetter than normal at least through next week.

Let me show some upper level  (500 hPa, around 18,000 ft) forecast maps that document the  development of this beast.   Today was a fine day, with a modest ridge over us (see map for 5 PM today-Tuesday).   This is the last day of warmth for a while.

 By 5 PM Wednesday, a trough of low heights (or pressures) has developed over the eastern Gulf of Alaska.
 One day later (Thursday 5 PM), a very strong low center is centered over western Washington and a huge, powerful ridge over the central NE Pacific.

Friday afternoon?  Now it has grown and extended into California.

 On Saturday at 5 PM, the infernal beast is now over the entire West Coast.

As you can imagine, this pattern is not going to result in any heat waves, as illustrated by the latest forecast for Seattle from the Weather Channel. No more 70s or 80s for a while.   Temperatures at or even below normal.

Precipitation?   You bet.   For the next 72 hours, wet offshore and modest rain over our local terrain.

 The next 72 h (ending 5 AM Monday) is far wetter, with several inches over the mountains, lots of moisture over eastern Washington, and substantial rains over northern CA.

The atmosphere has shifted to a very different configuration, one we have not seen for a while.  Find a sweater and protect you tomatoes.


  1. Will there be any winds? Or just drippy, gray, and boring?

  2. Plenty of cold still available and coming out of the north while at the same time moving daily, progressively more slowly east.

  3. And yet, still very little moisture on tap for north Whatcom County. Unfortunate, because it's much-needed, but our forecast doesn't look as dramatic as to warrant a "-zilla" label.

  4. This looks like an upside down omega. Is that a proper way to think of it?

  5. It was June first for a while but back to "normal" now :)

  6. Extreme low pressure causes local sea level rise. If the low pressure persists until the next spring tide (full or new moon) and the rivers are high with runoff, we will see coastal flooding.
    The local media, political pundits and the UWCIG will blame Global Warming and sea level rise.
    The reality is simply bad timing for a low pressure cell.

  7. Nice article again, Cliff. But there is absolutely nothing in the 10 day forecast that warrants "protecting" ones tomatoes. Heck, I have seen worse weather in June, and have never lost a tomato plant in twenty years of spring weather.

    Just one year did I lose all of my tomato plants, and that was because of an early onset of "late blight" in the month of August back in the 1990s...and that late blight was very wide spread in the Puget Sound region.

  8. Only Thursday appears to be somewhat below the normal high of 65 for this time of year. Still fighting a warm ocean I guess.

  9. Is Seattle going to see any rain? Yes, this past winter was very wet, but the past 7 weeks have been beyond abnormally warm and dry. Although it's great to read above that Oregon and Eastern Washington have been getting some rain over the past couple days, I am really hoping that Seattle can finally get in on some meaningful precip as well.

    I say this because I just watched King5 News on Wednesday evening, and they really played down any precip over the next week or so here, saying "downtown may see the occasional shower". They fully agree with your forecasted below-average temps, but do not share your optimism for meaningful precip - at least for those here in Seattle. The (unmaintained) grass here is already turning a shade of late-summer brown, which will become perfect wildfire fuel, rivaling that of last year, if this area continues to see no meaningful rain. I hope you have some news contradicting this!

  10. Hmmmm, highs in the mid 60s lows around 50 doesn't sound too cataclysmic.

    Throw in a few clouds and maybe some evening rain and I say welcome troughzilla!

  11. With La-Nina coming for this winter, the odds of having a Troughzilla will increase substantially. This is not a guarantee of course.

    I was looking on another weather site, where it was mentioned that a La-Nina with a warm PDO causes a severe weather across the northern tier of the US. We of course are in that northern tier and being that PDO has flipped back to warm, this could be an interesting winter for us here in the PNW. I'm looking forward to this adventure!

  12. I've noticed King5 and especially Rich Marriott seem to favor sunny weather and their forecast commentary reflects this. I love Scott Sistek's commentary over at Komo and seems to align closest to Cliff's.

    However, both King and Komo's weather web pages have gone to S&*t as they try and stay hip to be mobile and app friendly. What happened to reporting basic almanac stats like average daily high and low? I seem to have migrated to just checking my iPhone app and following this blog for insight into more significant weather developments.

    On a side and more controversial note, I'm not yet convinced man plays a statistically significant role in global warming, but I sincerely appreciate that while Cliff is a believer in man-made Climate Change, he still correctly writes off weather extremes in recent years to natural variability.

  13. Agreed on the KOMO/KING TV sites. Even the "new" Weather Underground site provides more information.

    BTW: Cliff, you may be getting more people from Northern California viewing your blog. Mentioned to Paul Deanno that he ought to let viewers know about it. Frequently, a lot of what happens here also happens in Oregon and NorCal. So, makes sense.


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

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