37" of Rain in Six Days at Mt St Helens!

  • Amar Andalkar
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08 Nov 2006 05:22 - 10 Nov 2006 09:27 #176398 by Amar Andalkar
37" of Rain in Six Days at Mt St Helens! was created by Amar Andalkar
If all the pictures of extensive flooding and washed out roads haven't emphasized the historic magnitude of our latest Pineapple Express, maybe some amazing stats will. The TV meteorologists are quoting 8-12" rainfall totals at lowland sites, but we all know that the mountains get MUCH more precip. How much more? I decided to sum up the rainfall totals for the past six days (midnight 11/2 to midnight 11/8) at selected NWAC and SNOTEL sites in the Cascades:

Mt Baker, MF Nooksack (NW side, 5000 ft): 16.3"
Mt Baker, Wells Creek (N side, 4200 ft): 10.2" (rain shadow)
Mt Baker Ski Area (NE side, 4200 ft): 17.9"
Mt Baker, Marten Ridge (E side, 3600 ft): 19.9"
Mt Baker, Elbow Lake (SW side, 3200 ft): 20.2"

Stevens Pass (4000 ft): 17.5"
Snoqualmie Pass (3000 ft): 19.3"
Stampede Pass (3900 ft): 16.2"

Mt Rainier, Sunrise (NE side, 6400 ft): 10.8" (rain shadow)
Mt Rainier, Paradise (S side, 5400 ft): 23.7", including 10.1" on 11/6
Mt Rainier, Paradise SNOTEL (5100 ft): 24.1", including 9.7" on 11/6
Mt Rainier, Longmire (SW side, 2800 ft): 13.9"

Mt St Helens, Sheep Canyon (W side, 4000 ft): 27.1", including 10.7" on 11/6
Mt St Helens, Swift Creek (S side, 3800 ft): 36.5", including 13.9" on 11/6
Mt St Helens, June Lake (S side, 3300 ft): 37.3", including 14.6" on 11/6

N Fork Bull Run (Columbia Gorge, 3200 ft): 27.7"

Mt Hood, Red Hill (N side, 4400 ft): 16.7"
Mt Hood, Timberline (S side, 6000 ft): 13.3"
Mt Hood, Test Site (S side, 5400 ft): 11.9"


Just how outlandish is 37" in six days? Well, the average annual precip at SeaTac Airport is only 38". Given the wholesale destruction of roads (and certainly trails too) at Mt Rainier caused by 2 ft of rainfall (see photos at Mike Gauthier's blog ), one can only imagine how much worse things must be at MSH, with 3 ft of torrential rain falling on its mostly loose, unconsolidated pumice slopes.

The June Lake SNOTEL on MSH is the wettest location in the entire Cascade Range, with an average annual precip of 170" since 1983. This exceeds any measuring station on Baker or Rainier or anywhere in the North Cascades, and even the Hoh Ranger Station in the Olympic rain forest averages "only" 134 inches per year. (Of course, some remote mountain areas in the Olympics do get more rain than MSH, but there are no measurement sites in those areas.) Although not an official record, June Lake probably has the highest average precipitation of any measurement site in the contiguous US, and its maximum of 232.7 inches in 1996 easily exceeds the official contiguous US record of 204.04 inches, also set in 1996 at Laurel Mountain, OR. Despite the recent deluge, this year's total precip is only 146", barely above average through Nov 8.

And ain't GW great? Every year or two now (Oct 2003, Jan 2005, Nov 2006, ...), we get a Pineapple Express that just shatters rainfall records left and right. This time, at least we all lucked out and it happened to hit before there was any real mountain snowpack to wash away, thus preventing untold greater destruction due to even more severe lowland flooding and also perhaps saving the upcoming ski season.


(Edited 11/10 to add Nooksack and Longmire data)

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  • peaceriver
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08 Nov 2006 05:41 #176399 by peaceriver
Replied by peaceriver on topic Re: 37" of Rain in Six Days at Mt St Helens!
interesting stat's Amar....37" WOW you wonder what those gullys/drainages looked liked filled with all that loose pumice wasig off the side.................

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  • Randito
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08 Nov 2006 08:56 #176401 by Randito
I wonder if there is still a rain gauge at Wynoochee Dam on the Olympic pennisula -- I have a memory of that location recording a record 300+" of rainfall a few years ago.

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  • Amar Andalkar
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10 Nov 2006 09:08 - 11 May 2014 09:28 #176404 by Amar Andalkar
Replied by Amar Andalkar on topic Re: 37" of Rain in Six Days at Mt St Helens!
A former NWS COOP station named Wynoochee Oxbow (located about 3 miles SW of the dam) holds the official WA state record for annual rainfall at 184.6" in 1931, but data is only available from 1931-1940 and many months of data are missing entirely throughout this period. It's hard to find any data online for Wynoochee Dam, other than streamflow and reservoir height. If anyone knows where to get the rain gauge data, please let me know.

However, while Googling various search terms I stumbled across this interesting article about skiing in the Wynoochee headwaters basin , also cross-posted at www.nwhikers.net/forums/viewtopic.php?p=16732. QUOTE: "The rain gauge at the Wynoochee Oxbow has averaged 164 inches of rain per year, making this the wettest spot at this elevation in the conterminous United States. This also results in very heavy snow cover, with the lowest-elevation subalpine and alpine meadow systems on Earth at this latitude. The subalpine zone generally starts at 2800 feet, with pure open ski bowls at 3400 feet and above. The Wynoochee Bowl, at the headwaters of the river, is an open horseshoe basin system, surrounded by basalt peaks, at an elevation of between 3000 and 5000 feet."

Seems like a fascinating place to visit . . . too bad that the Olympic NP trail report states "The access road to Wynoochee Trailhead is washed out. Check with USFS for details." That report was 10/24/06, even before the Deluge of 2006.


[size=small](Edited May 2014 to fix broken link to article which had changed, and add NWH link.)[/size]

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