Super-soaker: Atmospheric River taking aim on beleaguered #OrovilleDam
Anthony Watts / 17 hours ago February 15, 2017
We’ve already had two big events like this so far this year, now forecasts show a clear pattern of a heavily moisture laden “atmospheric river” taking aim directly onto the Oroville Dam watershed over the next week. Accumulated precipitation forecasts show that the Lake Orovile watershed will score a direct hit with the maximum amount of precipitation over the next 10 days (see graphic near bottom of this article).
Above: Computer forecast models indicate a powerful jet stream will continuously pound California over the next ten days and bring copious amounts of moisture from off of the Pacific Ocean into the state. This 10-day loop of predicted upper-level winds at 250 mb are in 6-hour increments from today until Thursday, February 23rd; maps courtesy tropicaltidbits.com, NOAA/EMC (GFS)
Meteorologist Paul Dorian of Vencore Weather writes:
There have been many occasions in the past in which floods have followed droughts in California and this recent time period is yet another example. In California, incredible amounts of rain have piled up in recent weeks across low-lying areas of the state, mountains of snow have accumulated in the higher elevations of the Sierra Nevada Mountains – and more is on the way. After a couple days with a break in the action, another storm is likely to arrive in northern California by later Wednesday and continue into Thursday and then a second storm looks like it will slam the entire state by early this weekend.
After a lengthy drought, California has been battered by potentially record-setting rain, with the Northern California region getting 228 per cent more than its normal rainfall for this time of year. The average annual rainfall of about 50 inches had already been overtaken with 68 inches in 2017 alone and another 6+ inches is possible over the next week-to-ten days. The latest computer model forecast of upper-level winds for the next ten days (Monday, 2/13 to Thursday, 2/23) does not hold out much hope for any significant drying in California. Powerful winds in the upper atmosphere (at 250 mb) will continuously pound California and bring copious amounts of moisture from the Pacific Ocean into the state. The total precipitation forecast map by NOAA for the next 7 days indicates more significant rainfall (and snowfall) is likely throughout the state.
More here: vencoreweather.com
The long-term forecast has rainfall totals withing the watershed that are showing the exact spot where Lake Oroville watershed is located will get 11.62 inches of rain over the next 10 days, the most accumulated rainfall in the entire western USA:
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Greg
February 15, 2017 at 4:34 pm
Thanks for digging out the numbers Willis. This does not look good. I hope those down stream are on good terms with the almighty.
It looks like dropping the evacuation to an ‘advisory’ is to let folks go home and start packing their valuables. At least that’s what I’d be doing.
If they don’t manage to lay down a lot of rocks and concrete, I don’t see that em. spillway holding up next time the water comes over it.
Richard G.
February 15, 2017 at 4:44 pm
Murphy’s law complications: The management team informed us at a press conference last week that the power plant at the base of the dam was out of service due to the disconnection of the transmission lines compromised by spill way erosion. There is also the threat of inundation due to the debris fan from the spillway erosion raising the river level at the power house. They can not run the generators if they are not connected to the grid load. These are rated at 16,950 cfs capacity.
This means that they can not draw down the free board beyond the floor height of the spillway gate structure. (Maybe 50 feet?) I have been unable to find any specs for this detail. This will limit their ability to exercise maximum flood control manipulation.
Bright side: So far the dam has succeeded at it’s primary purpose, flood control below the dam.
richardjstacy
February 15, 2017 at 7:23 pm
The watershed is 3,900 sq.mi. or so (Wikipedia) but you can count on it delivering a knockout in-flow being it’s already saturated. The immanent problem is that Lake Oroville’s surface is about 25 sq. mi. Multiply by the height of the emergency spillway wall, 30 ft., then, the result on failure = 5,280 ft./mile x 5,280 ft./mile x 25 sq. mi. x 30 ft. = 20,908,800,000 cubic feet of water in an hour or so, maybe less, when this thing unzips beginning at the parking lot-wall joint scouring out and accelerating toward the main concrete spillway courtesy of the tyranny of the majority in California. That’s 20,908,800,000 cf / 60 min. per hr./ 60 sec. per min. = 5,808,000 cfs in case you were wondering what a Democrat dam break looks like compared to the spillway flow now of 100,000 cfs to 150,000 cfs (38.72x!) This will be epic. Want to do something about it? Vote them out in 2018, PLEASE. Lives depend on it. Unless you consider the Delta Smelt, the Crazy Train and the cost of 20,000,000 illegals are more important than the 200,000 innocent lives immediately devastated, property damage beyond estimate, farmland destruction and the cost in today’s dollars of a new, competently re-designed Republican dam. This was NOT a natural disaster, it was completely man-made through purely Democrat / radical environmentalist drought-phobic miss-management of flow, stubbornly not building capacity (Auburn Dam, for just one example) miss-placed media hysteria of a documented drought long over, and the greed of Alameda and Los Angeles County Water Agencies who refused to pay for the fix 10 years ago. Water wars are expensive, this being no exception. I pray the citizens of our beautiful state finally awake and return governance to sanity. CA Lives Matter. RIP Oroville. |
