Possible Flood-Producing Rain Heading To Snoqualmie Valley Tomorrow, February 21st

**  Updated 2/20, 3:15PM:  NOAA officially issues Flood Watch for Snoqualmie Valley.  “SOME UNCERTAINTY STILL EXISTS. HOWEVER RECENT WEATHER MODELS HAVE FORECAST THE HEAVIEST RAINFALL IN EASTERN KING AND SNOHOMISH COUNTIES. IN THIS AREA OF THE CASCADE MOUNTAINS 4-7 INCHES IS FORECAST…WITH SOME HIGHER BULLSEYES. THE RIVERS AT GREATEST RISK OF MAJOR FLOODING ARE THE ONES FLOWING OUT OF THIS AREA…THE STILLAGUAMISH… THE SKYKOMISH…THE TOLT…THE SNOHOMISH…AND THE SNOQUALMIE.”  **

The National Weather Service says a rain storm is headed toward Western Washington, one bringing lots of soaking, tropical moisture, high snow levels and strong westerly air flow.  The warm, westerlies slam up against the west slopes of the Cascades which increases rainfall amounts there.  The Cascades saw massive amounts of snow over the weekend.  The Summit at Snoqualmie alone received 31 inches of new snow.  Now warmer weather is on the way, which melts all that new snow and forces run-off into mountain-fed rivers.  It’s a classic weather scenario for Snoqualmie Valley flooding; whether it’s minor or major flooding.

Weather forecasters say tomorrow’s weather system is similar to the one that produced major Snoqualmie Valley flooding in November 1990.  Don’t panic, though, those same forecasters also go on to say that the 1990 storm “was much stronger and lasted longer than this one will.”  Approximately 3-6 inches of rain is predicted for the central Cascades starting 4AM Tuesday – 4PM Wednesday.  Snow levels will hover around 6,000 ft. the entire time.  Flood-prone rivers flowing off the west slopes of the Cascade have the greatest flooding threat with this incoming weather system – that includes the Snoqualmie and Tolt Rivers.

As with any incoming storm in our area, the path is critical.  If it veers a little more south or north,  the rain total amounts can decrease.  You can check the latest weather forecasts at NOAA’s Snoqualmie Valley local  page.  If you want a forecast pinpointed exactly for your neighborhood, simply click on the map and the forecast will change.  If needed, you can monitor Snoqualmie River flooding at King County’s Flooding Services page.  Any flooding that happens will most likely occur Tuesday night or Wednesday, February 22nd.

Comments

  1. I was born and raised in Historic Snoqualmie and still live down here in the floodprone district. The numbers I’m seeing on Floodzilla and the King County site are not scary at all. Of course we all know in floods that things can change in a matter of a few hours and what was going to be a minor flood (which is what the numbers say now) can turn into a major flood (November 2006 case in point).

    I was here for the 1990 flood. I took my mom out of her house in Historic Snoqualmie in a row boat. We’re talking the water was pushing 75,000 cubit feet at the forks. HUGE. If we had that kind of flood now, with the lack of river dredging and the massive amount of building that has happened in the past 22 years, my house, which only floods over 53,000 cfm, would be probably have 5 feet of water inside. 75,000 cfm goes a lot farther now – way more than in 1990.

    Lets hope you are wrong. I’m sure hoping so.

  2. I do appreciate reading your blog. I like your take on things.

    Also, another note on the whole flooding thing. Both in 1990 and especially in 2009, the ground was already saturated from extensive, continuous rain and/or snow previous to the warmer, pineapple express hitting our area. Since we haven’t had extensive rain and there’s no local snow, I factor that into my thinking that this won’t be bad at all. Plus, like you said, this system isn’t suppose to last as long.

    I’ll never forget the January 2009 flood. I can remember about a week out, looking at the local and pass forcasts. We had over a foot of snow on the ground still, and I can remember calling my brothers betting them that we were going to have a major flood over 50,000 cpu @ the Forks on either the 6th or 7th. Both of them took me up on it and I got $50 bucks out of the deal! Of course we were all too busy cleaning up our properties to collect on the bet. Dang. I need to remind them of that.

    Keep up your posting – I do enjoy it!

  3. I just checked the predictions – they have doubled the numbers. Dang I hope I’m not wrong on this one! Thanks for giving the heads up and I will be tracking the numbers the next 36 hours right along with you.

  4. The latest flood prediction is 26K cfs at the falls, or 14 & 1/2 feet, about a 1.5 feet above flood level.

    Don’t know what this means for Historic Snoqualmie.

    • I am still not sure this will be anything more than minor. It’s probably just good to know there is a potential flooding risk – even minor. Seems the weather this winter isn’t quite doing what it’s predicted to do:) I don’t think the City of Snoqualmie starts paying big attention until it gets to phase 2 flooding stage and is still rising.

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