April 01, 2010

Storm Watch

9 PM Update: The latest run (WRF-GFS) is virtually identical to this morning's forecast. This should be a good storm, but we are not talking of an event like the Chanukah Eve or Inauguration Day windstorms. The NWS has just put out an ominous bulletin on their web site and to show it is serious it is all red.

An unusually strong spring storm is approaching and will hit tomorrow. It could end up being the strongest winds in several months for the Northwest lowlands. And we have the added complication of some trees starting to leaf out--which makes them more vulnerable to a strong blow.

Let me show you a series of surface pressure charts for tomorrow, produced by the UW WRF numerical prediction system. The maps are for 8 AM, 11 AM, 2 PM, and 5 PM tomorrow.
A perfect track for strong winds over Puget Sound and the WA coast--right across the NW corner of the Olympic Peninsula (see my book for information about optimal storm tracks). The largest pressure gradient and strongest winds will be later in the afternoon...not the morning...for Seattle and vicinity. What kind of winds? Would not be surprised to see 40-60 kts over Puget Sound and 20-40 kts over land. Expect some power outages.

And the fun doesn't end there! As the low moves past us, there will be a westerly surge through the Strait of Juan de Fuca that will hit Whidbey, northern Olympic Peninsula, and southern San Juans.
You want more? You got it! Moderate to heavy precipitation will strike the region, with 2-5 inches of precipitable water in the mountains. Guess what, a lot of that will be in the form of snow...with some areas getting several feet. Check the 24h snowfall ending 5 AM Saturday below. Get those skis ready! But a warning--the avalanche danger is going to be substantial when this is all over.


  1. Wow! Let's get it over with this weekend, hey? I mean, it's fun and all, but...

    We're going grey whale watching on April 11th and I will be bummed if we're doing it in serious wind and rain.

    Thanks for the great info, as always, Cliff. This does feel like November weather... poor confused trees!

  2. Are there any other models that indicate differently for this storm? Or are they pretty much in agreement?

  3. Can't wait to see what the MM5 models show here in a couple hours. Interesting to watch this storm develop on satellite too. A little darkening happening now behind the storm on WV. Yeah, you taught us that.

  4. I love your blog. A lot of it goes right over my head, but maybe with time I will learn a few things.

    One thing I wish you could do is make the pictures and especially the words and numbers on the pictures bigger so I can read them!

    Thanks for all you do.


  5. Always interesting to see things will actually turn out compared to how they were forecast. Right now the NWS has the strong winds starting at 'exactly' 11AM and blowing 28-38KT(Everett terminal forecast). But will the storm be 3 hours early or 3 hours late? Will the winds be as strong as forecast for as long as forecast, or different than forecast? I don't know how much stock to put in forecasts of these storms because the forecasts are fairly exact and usually in the ballpark, but if you think you've got until exactly 11AM to pick up the loose stuff in your yard (that might be blown away), you may well be disappointed.

    Anyway, I appreciate the update Cliff.

  6. Ready for any sized storm, especially after this extremely plain winter.

  7. so does this mean that i should buy more propane for my camping stove?

  8. @Brenda, you can click on the graphs and charts and they will open larger on a page by themselves

  9. Brenda,
    Click on the map to make it bigger. Click on it yet again to further enlarge it.
    Then use the back arrow to get back to the blog.

    Thanks for sharing your expertise in the blog. I enjoyed your book. Things still go right over my head with the clouds!

  10. Sting Jet time? (according to a topic covered at a Hobbes Memorial lecture) The sat photos have that look to them this morning...

  11. Hi Cliff,

    Can you give us a high resolution picture of the mountain pass conditions for the Easter Sunday trip? It looks like Sunday will be much better then Saturday but still an adventure.

  12. Starting to wrap around a bit this morning on the 0700 image. Winds beginning to pick pup here in BLI.

  13. If you had to cross the sound on a ferry from Whidbey to the mainland with a fearful child today, when would you do it???


    Karen (Seattle)

    PS Love this blog, it's so much more entertaining and informative than the typical weather sites.

    PPS We saw those cloud anvils on Wednesday, they were indeed magnificent!

  14. Lots of rain (steady since 2:30 AM) mixed with some snow right now on Copalis Beach. 35 deg. 990 mb and still dropping. Wind moderate so far with gusts to 24 kts.

  15. Cliff, you prepared us for snow in the mountains, not here in Chimacum! About 7:45 this morning the pouring rain suddenly turned to lots of SNOW! and it's sticking, and still coming down! Looks like we're up to at least an inch already.
    I just hope the wind starts gently and blows the wet snow off of all the branches before the big wind comes...
    Many thanks for this lovely and informative blog!

  16. 2 inches of snow at 1700ft. Snow blowing in sideways from the east always a good sign. First snow since Jan. 8th. Yakima has never recorded snow in April, but I don't think the snow is making it there.

  17. I'm surprised we only have a wind advisory... with a 970-975 low tracking right over tatoosh island I'd expect higher winds. The Hanukkah Eve Storm had a 970 low track over southern Vancouver Island, but that one produced higher winds because it was moving faster when it was over us. This storm will be upon us in the next couple hours or so... so get ready!!!
    Also, Cliff, how do you make your pictures on the blog clickable? I can't find a way to make mine that way. Blogger also doesn't automatically reduce my pictures in size when I take them from the internet - I have to manually save them and upload them from my pictures file on drive C.
    Thanks! charliesweatherforecasts@blogspot.com

  18. Now 4 inches at noon. While snow in April is rare, its dry and powdery! Its not even dripping off the roof yet. Our wind machines kicked on last night too. Crazy to see this while frost protection at night is underway.

  19. This seems to be one of the longest lasting wind storms I can remember in a long time. Although the high wind warning for the San Juans originally started for Fri morning, we started getting 30+ sustained winds starting at midnight, with 43 at 3 am on the Kelp Reef buoy outside our house. Then the warning was supposed to end at 9:00, but it's now been extended to midnight. That's more than 20 hours of high wind. That's a lot for the trees to endure.

    Am I just remembering wrong after a long fairly calm winter, or is this length of high wind activity unusual? And why is this one acting so differently from what it was forecast to do?

  20. My family and I got to see this all up close. We just spent a week in and around Olympic National Park. Got see Hurricane Ridge closed due to wind and snow. Had to leave Heart of the Hills because of the same. Froze our tootsies camping at the Hoh. Had the rain break long enough to get in a hike. Then a few wet days at Kalaloch topped off with 25-30 MPH winds on the beach this morning!

  21. Forgot to mention the 5th wheel a few sites over with the weather station on the roof. Coolness!

  22. http://www.youtube.com/watch?v=ZK7tzOHX8CQ&feature=player_embedded Great video from Medina... man do I ever HATE that bridge! Anemometer at our house has recorded a 46 mph gust from the S and we've sustained in the 25-30 mph range for a while this evening. We are up to 0.63" of rain for the day so far. Nice storm!


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