October 17, 2009

Amazing Rain Intensity


An hour ago, an amazingly intense line of thunderstorms passed through central Puget Sound. At my house there was nearly .4 inches over 15 minutes--and my gutters did not do very well with that volume of water. Take a look at the radar--you can see areas of red...those are intense rainfall areas...and one went over my house--and there wasn't any hail, which is usually associated with such high values. Just amazingly intense rain with big drops. An image from the new Rainwatch system (which will become public soon) is show below as well...many lowland locations have gotten 1.5-2 inches over the last day. Some areas received over two. Scattered urban flooding has occurred. No issue with the Green River--early in the season and its watershed did not get sufficiently large amounts of precipitation for any concerns.

19 comments:

  1. We have had 3 inches of rain over the past few days..3 blocks south of the Woodland Park Zoo. Today has seen heavy rain and glorious periods of sun.

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  2. Cliff, Renton is still 73ยบ You mentioned the sinking air on the radio, but is Renton special relative to its location?

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  3. Some more light showers look to be passing through my area here soon, which may add a little more to my already fallen rain fall amount of 1.14" today. Fairly mild day here as well with my high reaching 62. Guess ya could say it was a tad humid as my dew point reached a high of 60.

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  4. PWS's in the immediate Sequim area picked up 1.5 to 2 inches of rain since 8:00 pm last night. I was surprised - the rainshadow wasn't that prominent over the north Olympic Peninsula as expected.

    I think a closer analysis will prove the Renton data to be bogus. It was apparently still 72 there during/after an intense downpour - I don't think so.

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  5. We had 5 inches of rain in our trash can (near Greenlake). Why do we have so much more water than all the official reports?

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  6. I have never seen my gutters overflow the way they did this morning. I think the rain was so intense it swept the season's accumulation of leaves off the roof and right into the gutters... fortunately, there weren't too many leaves yet. But we had a waterfall coming down across a window that usually only gets a few drops. I'll be up there scouring the gutters tomorrow.

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  7. I drove down to Salem, OR today and back again. Four times I went through a deluge that made it impossible to see anything through the windshield. Traffic on I-5 slowed to about 30 mph for a few miles until the road was visible again. The ruts in the road made by trucks filled with water and that made for some impressive "rooster tail" splashing by cars. Same on the trip back--and then in some spots, the pavement was perfectly dry. Not a good day to be driving.

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  8. Mainstreeter...it is clear that something is wrong with Renton...nearby stations are much cooler....cliff

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  9. There was a commercial a while back that Renton was "ahead of the curve"

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  10. Not sure why you've mentioned the Green River so frequently the last couple days. Why aren't other rivers of interest as well?

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  11. http://www.youtube.com/watch?v=nKhDrbEmbKw&feature=player_embedded

    video (somewhat sped up) shows clouds (yesterday's storm? don't know) sweeping in over the Bay and up Queen Anne, where the rain comes. It's pretty neat.

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  12. @Fleetwood... they've been having problems at the Howard Hanson dam on the Green River and therefore, they aren't going to be able to hold a full pool in the reservoir to avoid downstream flooding in Auburn and Kent. The pool level the USACE thinks is safe will almost certainly cause big flooding in the valley because the river will overtop the levees (with the potential for that to cause levee failure).

    All that means that they are really watching big rain events in the Green River valley... they need to provide as much flood warning as possible because many more people and businesses are likely to be flooded than in years past. There hasn't been a full-on flood in the Green River valley since about 1959 and clearly there's massively more development and at-risk population now.

    You can read more about the risk of flooding and the situation at the dam here: Concern rising as flood season nears in Green River Valley and here: Army Corps of Engineers races the rain clouds in Seattle District and you can watch the river levels here: River level just below Howard Hanson Dam... and finally, here's the data for all the rivers in Washington State.

    Have fun! I find the rivers and the flood monitoring almost as interesting (during the flood season anyway) as I do the weather itself. :-)

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  13. I have been looking at the GFS and it has been hinting at some major changes sometime next week for several runs now. 850 mb temps are forecasted to go below 0c for all of western was as well as the 1000-500mb thickness. Also, the GFS shows plenty of moisture around. I would like to know if any of you have been watching the models and if you think we could get a little taste of winter here in late fall ? Cliff, any thoughts about the weather for the last week in October around here?

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  14. mwhybark -- that video is of Saturday's storm from KOMO's Columbia Center Tower Camera. Time codes are from 3:26 to 3:35 p.m. if you want to match to radar. -Scott Sistek/KOMO

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  15. I keep a rain gauge in our backyard in Wedgwood. We live in the "trough" between View Ridge on the East and the other ridge on the West. Typically we receive more rain than the reporting stations, likely because the ridges act to lift and scrub moisture out of the airflow. Coincidentally in the winter we tend to be notably cooler than reporting stations due to cold air sinking down the two ridges and sitting in our valley.

    We ended up with 3.10 inches of total rainfall from the beginning of the system to the end of the rainfall which occurred Saturday after the front passed, although there were some showers Saturday evening. Sunday morning and Sunday were entirely dry.

    Now I'm turning my attention the Gulf again to see how the lows line up and whether tropical moisture will feed in from that hurricane just out past Hawaii.

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  16. Cliff, I just heard on the radio that NoAA is placing a mobile radar installation at Westport for the winter.

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  17. Check out my new Seattle weather blog everyone. It will be updated several times a week.

    http://seattleweatherblog.blogspot.com/2009_10_01_archive.html

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  18. I think we all needed a more quiet and typical weather week after last weekend.

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