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gb
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PostTue Nov 06, 2018 7:08 am 
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Ski wrote:
But do continue on. I enjoy hearing about how the sky is falling and the world is coming to an end. lol.gif

Again, you go off topic because you are afraid I might say something about global warming. But as I said this is about rainfall.

What was obvious to me was that the graph you posted made 2015 and 2017 look identical despite the fact that 2015 was a drought year in an El Nino year and 2017 record rainfall in a La Nina year. The graph you posted was essentially meaningless, the wrong tool to evaluate the recent very heavy orographic rains.
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PostTue Nov 06, 2018 7:26 am 
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thunderhead wrote:
Ya, that was a very ordinary rain event with very minor flooding and very isolated power outages.  Get about what, 5 of these every year?

You prove you know very little about weather. Last winter there was no long lasting event of this intensity (11" over 5 days). The winter before there was an extreme event that lasted about 8 days (I posted on that event) that was responsible for substantial snowpack on the glaciers above certain elevation ranges in both the North and South Cascades. An estimate of those elevations based on NWAC telemetry was in that post. It appears that very heavy rain events seldom last as long as eight days. I know that in the mid-70's there was a period of 4-1/2 days when it snowed 109" at Mt. Baker. Figure 7-7/1/2% water. That event was exceeded I believe in about 1998-99 though I didn't record that. In 1990 ending in the first week of February Mt. Baker received about 400" of snow in 3-1/2 weeks (again figure 7-7-1/2% water content as the skiing was universally great in that period. When the snow level rose briefly to 4500' there was a major avalanche cycle. I took an image that I used in my avalanche class of a 13' slab at the Blueberry rope tow that I used in my avalanche courses. There were many other large slabs including one that was visible off Bastille Ridge onto the Mazama Glacier that looked to be 20-25'. The large avalanche off Mt. Snoqualmie that carried old growth into the Alpental parking lot took place on the same day. This extreme long lasting snowfall event was exceeded by a similar event in 1998-99 when Baker recorded over 1140" of snowfall and reached a peak depth of 337" at the lodge. On both of these events, a NWAC friend provided me with the archival telemetry. Although 1998-99 was considered a world record, it is likely that near Mt. Siverthrone on the BC Coast that snowfall has exceeded the Baker record.

Now granted atmospheric river events produce more water equivalent than any snowfall events are likely to do because the atmosphere is warmer. But these snowfall events provide a glimpse of what record events in the NW look like.

Was this a record event? no. I said that right off the bat. And as to flooding; that is strongly related to having substantial snow at low elevations that is subjected to warm temperatures and winds accompanied by an atmospheric river event (rain doesn't melt much snow, warm temperatures do - source - avalanche literature). At this point in time there was no snow below about 4300' especially that elevation near Snoqualmie Pass where I made that observation on October 31st just before the heavy rains began.

So river run off and heavy rains are not the same thing. The highest river run offs, read flooding, especially east of the Cascades takes place in the absence of significant precipitation during prolonged warm and likely sunny weather in the spring as it did at near record levels this last May. Flooding west of the Cascades comes as described in the previous paragraph.
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thunderhead
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PostTue Nov 06, 2018 8:10 am 
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2 inches per day for a 5 day event is pretty ordinary for a rainforest that gets 100+ inches of precip per year.

For example this guage on the flanks of baker has recieved even more precip, 25 inches over the past few weeks, but the slope of the line is only a bit steeper than normal.

www.wcc.nrcs.usda.gov/reportGenerator/view/customChartReport/daily/910:WA:SNTL%7Cid=%22%22%7Cname/CurrentWY,CurrentWYEnd/WTEQ::value,WTEQ::median_1981,PREC::value,PREC::average_1981?fitToScreen=false

If lowland rain guages were this high it would be quite extreme, but our mountains get a LOT of precip all the time.  You have to get a number of 10 inch storms every year if you want to get to those 100 plus yearly totals.
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gb
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PostTue Nov 06, 2018 8:26 am 
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thunderhead wrote:
2 inches per day for a 5 day event is pretty ordinary for a rainforest that gets 100+ inches of precip per year.

For example this guages on the flanks of baker has recieved even more precip, 25 inches over the past few weeks, but the slope of the line is only a bit steeper than normal.

https://wcc.sc.egov.usda.gov/reportGenerator/view/customChartReport/daily/910:WA:SNTL%7cid=""%7cname/CurrentWY,CurrentWYEnd/WTEQ::value,WTEQ::median_1981,PREC::value,PREC::average_1981?fitToScreen=false

If lowland rain guages were this high it would be quite extreme, but our mountains get a LOT of precip all the time.  You have to get a number of 10 inch storms every year if you want to get to those 100 plus yearly totals.

Misleading. Five days in a row and 11" is extraordinary. I just posted what extreme events look like. Regarding precipitation they don't appear to be that amazing. Take for example Seattle. Isn't Seattle's average rainfall about 36-38" and the two succeeding record rainfalls the past two years for the October May period were 45". Also the Elbow Lake graph being a bit above normal is pretty surprising given that there were 2 and one half weeks straight of amazing and totally dry Indian summer in Mid-late October! That was the best hiking weather of the entire season.

The outliers are the 2003 GPW and 2007 events as well as some recent amazing flash flood events near the Goat Rocks, in the Chiwawa, and along the North Cascades highway that are obvious from erosion channels and debris flows. The big rainfall event (was it 2007) on Mt. Rainier produced 18" of rain in 36 hours. That was likely something like a 1000 year event comparing the rainfall to other extreme events. The flashflood? on the west side of Mt. Maude that eroded a twenty foot deep channel and exposed two unmixed layers of GP tephra was obviously in that location the biggest rainfall event since the tephra was put down some 11,300 ya.
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puzzlr
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PostThu Nov 08, 2018 2:15 pm 
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I don't know from the Queets, but I want to respond to the original title of this thread re road damage and rain gages.

Heavy rains fell in the Middle Fork Snoqualmie Valley on Nov 1, 2 and 4. Surprisingly, the most damage to roads was done on Nov 2, the lowest of the three peaks on the gage, even though it was 30% less flow than the Nov 4 peak. In fact the 15,400 cfs peak on Nov 4 generated almost no flow in the creeks that cross the road between the Taylor River and the Dingford trailhead. These high water marks are relatively normal for the fall season, but I was surprised how the effect on the road was not very closely correlated to the gage readings. Besides the Nov 4 rain "missing" this part of the valley, the only explanation I can think of is that the Nov 2 rain was more sustained.

The damage was bad enough that the USFS responded faster than normal by getting an excavator out on Nov 5 to repair the scouring.

TANW1 gage
TANW1 gage
Garfield Wash after USFS repairs on November 5, 2018
Garfield Wash after USFS repairs on November 5, 2018

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PostThu Nov 08, 2018 7:43 pm 
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puzzlr wrote:
Surprisingly, the most damage to roads was done on Nov 2, the lowest of the three peaks on the gage, even though it was 30% less flow than the Nov 4 peak.

Perhaps the damage on Nov 2 correlated to the cumulative rain from Nov 1 & 2?  Then the break on Nov 3 reduced the effects of the single day event Nov 4.
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PostThu Nov 08, 2018 8:59 pm 
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When it rains,it pours

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timberghost
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PostFri Nov 09, 2018 5:20 am 
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When it pours it rains
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iron
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PostTue Nov 13, 2018 12:57 am 
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gb: when are we getting any rain? this is ridiculous.

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PostTue Nov 13, 2018 5:31 am 
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puzzlr wrote:
The damage was bad enough that the USFS responded faster than normal by getting an excavator out on Nov 5 to repair the scouring.

Well that's better than the Skykomish ranger district does. When it was reported the road up Miller river was washing out the road crew person just commented " Well guess we will have to put in for more funds in the spring for flood damage". I understand that they are limited for funding and personnel but some preventive or standby damage control could save a lot of time, money and road closures. I know when I am driving the roads out there I pack a shovel to unplug culverts or water running down the road instead of the ditch. But times have changed and the world has moved on.
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Kim Brown
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PostTue Nov 13, 2018 1:39 pm 
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timberghost wrote:
Well that's better than the Skykomish ranger district does. When it was reported the road up Miller river was washing out the road crew person just commented " Well guess we will have to put in for more funds in the spring for flood damage"

But there are occasionally funding sources for damage repair. Maintenance dollars are rare if they exist at all.

On the bright side, one could always hope for a good, old fashioned ERFO-qualifying event up.gif

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PostSun Nov 25, 2018 8:16 am 
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Here comes another intense rainstorm, shorter in duration than the last but with very high rainfall rates NWS:

Quote:
Meanwhile, high pressure aloft will prevail over the region today

for dry weather for much of the area. The threat of rain will

slowly increase tonight as a stronger warm front approaches from

the west and moisture transport strengthens. Rain rates should

begin rapidly increasing over the south-southwest slopes of the

Olympic range late tonight.



On Monday, periods of heavy rain can be expected on the north

coast and south-southwest facing slopes of the Olympic range.

Locally heavy rain is expected on the southwest slopes of the

north Cascades Monday afternoon. It appeared that the heaviest

rain will occur Monday night, where local amounts of up to 10

and 7.5 inches on the Olympic range and north Cascades,

respectively, could fall during the 24-hour period ending at 4 AM

PST, Tuesday.
In general, the models were a little wetter than

the previous runs. This means that there will probably be more

rivers, draining off the Olympics and north Cascades, approaching

flood stage. A Flood Watch was issued for the Skokomish River in

Mason County. This river is forecast to reach flood stage Monday

evening.



Expect the cold front to move across the area on Tuesday for

falling snow levels. Rain rates will also quickly drop off behind

the front but there will be a few more rivers, such as the

Nooksack, in flood or close to flood stage during this time.
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gb
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PostTue Nov 27, 2018 8:18 am 
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There were several daily 24 hour rainfall records set for the period ending 4 am today. Perhaps more impressively Buckinghorse in the center of the Olympics recorded 8.5" of rain in 36 hours and many Olympic locations were not that far behind. In the Cascades Elbow Lake near Schreibers Meadow got 7.5" of rain, and Mt. Balker Lodge over 5". Unfortunately as a snow event or an event beneficial to glaciers the freezing level yesterday morning was around 9000' and fell to about 7000' + this morning. So only the highest glaciers should have gotten much snow.

Inland perhaps at Glacier Peak or so freezing levels were much lower with east winds and for Lyman Lake for instance this was a positive snow event but with much less precipitation than near Mt. Baker.

South of Snoqualmie Pass rainfall amounts were not nearly as great, either.
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iron
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PostTue Nov 27, 2018 1:43 pm 
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Ski wrote:
not that big a deal - the river didn't even get up to 60,000 cfs yet.

USGS 12040500 112718 0030 PST 46900 CFS
USGS 12040500 112718 0030 PST 46900 CFS
USGS 12040500 112718 0930 PST 44100 CFS
USGS 12040500 112718 0930 PST 44100 CFS

when it goes up over 65,000 you know they've got some serious rain going on up there.

no reason to panic.

considering it went from basically no rain for a week, to 60000 cfs should tell you something, i think.

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PostTue Nov 27, 2018 6:00 pm 
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Ski wrote:
typical November-December big system coming in off the Pacific. happens every year.

Yeh, typical. Just 24 hour daily precipitation records.  wink.gif 8.5" at Buckinghorse is a very big deal in 24 hours. Bet you anything that is the greatest 24 hour rainfall anytime this winter by quite a lot. It could be hard on roads and trails. In major storms, rates of 3-4" is about as much as one would see in 24 hours, very occasionally 5". As far as storms goes this was of pretty short duration which will help the rivers, but not roads and trails. Any damage would be in the Olympics, near Mt. Baker and possibly east to Mt. Shuksan. Also trails that are not too far east south of the Skagit for a ways. By the time you get to Marblemount rainfall was down to 3", the same as Snoqualmie Pass.

As far as I know the greatest 36 hour rainfall was about 18" at Mt. Rainier, which historically would probably be on the order of a 500 year event. In recent years I don't recall seeing 8.5" in 24 hours. After each big storm and at other times also I check rainfall in the Observations section at the NWS, and also NWAC and State Observation rainfall charts.
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