Skagit River Flows???

sroffe

Active Member
For you guys that know the Skagit River, I have a observation and question?

Noticing yesterday that the river in Concrete was flowing at 100,000/cfs. Looks like it took about 24 hours for that surge to reach Mt Vernon today. Am I reading the graphs right? Does it take that long to see the flood waters from the upper river to reach Mt Vernon?
 

Salmo_g

WFF Supporter
Usually less than 24 hours from peak at Concrete to peak at Mt Vernon. But it depends on where the rain lands. A good (real bad) pineapple express dumps many inches of warm rain on a couple feet of snow lying between 2,000 and 6,000' elevation. Pushes the flood faster. This isn't that big an event, therefore water velocity is slower. It was 7' above flood stage at Concrete yesterday, only 4.5' above at MV when I checked this afternoon.
 

sroffe

Active Member
Thanks Salmo,

Is there a lot of variance in the gage readings? I would have thought I would have seen 100,000/cfm down in Mt Vernon today. I suppose +-10% is pretty typical for variance.
 

KerryS

Ignored Member
Thanks Salmo,

Is there a lot of variance in the gage readings? I would have thought I would have seen 100,000/cfm down in Mt Vernon today. I suppose +-10% is pretty typical for variance.
As the water moves downstream it spreads out, elongates so to speak. As salmo mentioned a lot of it has to do with what’s behind the flood. If it drops quickly at Concrete the volume pushing it downstream lessens and allows the water to spread itself over more of the river.
 

Salmo_g

WFF Supporter
Sroffe,

It's fairly common for the peak flood flow at Concrete to be higher than the peak at Mt. Vernon. Counter-intuitive to me too, but flows attenuate in the downstream direction. All that same water, and more, will pass the Mt. Vernon gage as well, just not bunched up in exactly the same way. There's a lot about hydraulics and hydro dynamics that I don't understand.

Sg
 

_WW_

Geriatric Skagit Swinger
WFF Supporter
Sometime Wednesday the Nookachamps started flowing backwards and filled up the lowlands around Clearlake. This is some of the spreading Kerry is talking about. All of this water around town here will be here until mid July - unless we have a winter-time drought
 

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