Tuesday, December 21, 2010

This one goes to eleven

In case you missed it, the title of this blog entry is a famous line from "This is Spinal Tap" - referring to a new and improved amp that goes even higher than ten. The December Storm of 2010 certainly has that "eleven" feel to it...

What started out as blip on the fantasy weather charts matured into a full blown "hide the women, children and dogs" prediction - it did not disappoint. I suppose the appropriate joke would be "this is moisture tap" - you can see in the above Eastern Pacific Water Vapor chart; there was a conveyor belt of warm, wet air from the tropical Eastern Pacific. A low pressure spinning off the northwest coast has been pumping this air directly into the Sierra for an extended amount of time. An unusual western flow of air near the Canadian border blocked this low from progressing eastward; thus the extended weather pattern. I have heard various debates as to whether this was a true "Pineapple Express" event; but either way, it sure was sweet!

This storm was not a complete surprise, many of the weather models picked it up in advance. While we have occasionally seen storm total predictions in the 10+ inch range, rarely do they actually come through at those final tallies. For whatever reason, the models pretty much nailed this one though.

5 day HPC Storm Total Predictions for the Friday to Tuesday Period, Dec 17-22
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The heavy precipitation was expected to be accompanied by high snow levels; in the 7000-8000 ft range, so we pulled the boating gear out of storage and waited for the skies to open up... And they did.

Here is plot of the weather station at Johnsondale, about 25 miles upstream of Kernville, at an elevation of a little over 4000 ft. As you can see in the third panel, the total precipitation measured for the 5 day period from December 16th to 21st was 14 inches. Surely the orographics at the crest would have increased that total, resulting in (at a modest 12:1 ratio assumption) 15+ feet of snow!

The Johnsondale Weather Station Data

Of course with the high snow levels, a lot of that precipitation came down into the Kern River, causing a peak flow on Sunday, December 19th, of a little over 21,000 cfs (last years spring snow-melt peak was around 9,000 cfs). Below is a chart of the river flow at the Park in Kernville. You can also see that the storm added some 50,000 acre feet to the lake storage.

Kern River Flow, Precip and Lake Storage Data

The rain started in earnest on Friday Night, so Saturday we went up for a couple of runs on Brush Creek. When we got there the level was 3 on the gauge; a fine level, but a little disappointing considering the magnitude of the storm predictions. After 1 run down it had risen to 4, on our second run down it reached 5 - now we're cookin'!

The next evening it continued to rain steadily, and by morning time you could tell things were different. As we headed up the canyon all sorts of creeks that we had never seen before were cascading out of the mountains and washing across the road. Not only that, but there were several rock and tree falls as well; despite the distinct possibility of getting stuck on the wrong side of one of these falls, we pushed on upstream anyway to check out Brush Creek.

Just Another Day Driving up Canyon

When we finally pulled into the Brush Creek Parking lot, I had a brief moment of excitement - the gauge was at 10! I had paddled this section as high as 7 a few years back at peak spring melt, and it was awesome. Ever since then I wondered if the creek ever got too high to run, or if it just got better and better. My enthusiasm was quickly squelched though as a quick look at the bottom section of the river revealed that 10 was, in fact, too high. The banks of the creek were entirely made up of strainers; not eddies. There were also various other wood hazards thrown in the middle of the current. While a kayak decent was not to be, a hike up the creek was definitely in order.

Um. The portage actually looks like a portage...

The Limbo Log is Long Gone

Triple Drop looking like a Single Drop
The Z-Drop below Speedway


The Gauge at Brush Creek - Level? Too many ABU's

After the hike we got back in the car and checked out South Creek Falls; normally a trickle, this was a torrent sending spray up above the road level - awesome.

Rebecca at South Creek Falls (1000 cfs?)

After trying to stay as dry as possible in the torrential rain, we ended up deciding to get wet on a more reasonable stretch of river - the class IV Cable Run. When we got back to town, the river had risen to 14,000 cfs from about 6,000 cfs earlier in the day. By the time we got on the water and did our run we ended up pretty much on the peak of the flood at 21,000 cfs. There were some huge waves on the run, lots of trees in the water and the eerie sound of large boulders rolling along the bottom of the river as we were paddling down. All in all a very spectacular day!

The Park in Kernville at about 14,000 cfs

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