Which came inches away from flooding all of Sacramento, and even with the improvements in levee strengthening and Folsom Dam, Sacramento is still only prepared for a 200 year flood event when the gold standard, and what we need to work towards, is 500 year protection.
A helpful flood protection graph (showing the level of flood protection in various cities, including Sacramento before the levee and Folsom Dam upgrades brought us to a 200 year level) can be found at http://www.water.ca.gov/levees/history/floodprotect.cfm
An engineer’s report from Sacramento Area Flood Control that was just completed (February 1, 2016) gives detailed information on Sacramento’s flood threat and plans for reducing it, available at http://www.safca.org/documents/Assessments/Draft%20Engineers%20Report_02.01.2016_FINAL_v4.pdf
An excerpt from the 30th anniversary story from a KCRA Report:
SACRAMENTO, Calif. (KCRA) —It is the 30th anniversary of one of the costliest and devastating storms in the history of Northern California.
From Feb. 11 to Feb. 20, 1986, a series of three storms, each stronger than the previous, brought record-setting rain that, in some areas, overwhelmed flood control measures.
In the end, the storms claimed 13 lives and damage was estimated at $400 million.
The storm also brought eventual changes to California’s existing flood control system.
‘Atmospheric River’ slams Northern California
The February storms were a classic Pineapple Express system, or what we now call an “Atmospheric River.” The system was typical of the scenario that has usually given California historic rains. Satellite images from this time show a long line of clouds streaming from south of Hawaii to California. There was a long line of deep moisture being pushed along by a jet stream — that one pilot report measured in the 200 mph range (that’s very strong).
It’s also important to think about the technology that existed in 1986. Computer models were not as good as they are now, especially beyond 72 hours.
There was no Doppler radar. Actually, there was only one weather radar in the entire state! Remote reports of stream and river levels were also not like they are today.
We used to only get a few measurements per day instead of the instantaneous reports we get now. There was no internet for collection and dispersion of data.
But despite these challenges, flood forecasters did an amazing job with the data they had.
Round 1: The rain begins
Rain started to fall Feb. 11 in Northern California. The first wave of rain wasn’t too bad, while the rain totals were high, there weren’t any problems caused by the first storm.
During the next day and a half, Sacramento received 1.96 inch of rain and Blue Canyon got 4 inches. This wasn’t too unlike some storms we have had so far this year, and our flood control systems can easily handle rain totals like that.
Round 2: Second storm starts Valentine’s Day
The rain didn’t let up for long, but there was a pause between Round 1 and Round 2. The second storm started on Valentine’s Day, Feb. 14, 1986, and lasted through Feb. 16.
This storm was stronger and wetter than the first. The rain total in Sacramento reached 3.11 inches and Blue Canyon got 11.54 inches.
After five days of rain, streams and creeks were near full — if not overflowing — and major rivers were running fast. Inflows to Folsom Lake jumped from around 20,000 cfs at the start of Round 2 to around 80,000 cfs at the storm’s conclusion.
Round 3: Final storm makes big impact
The final storm began Feb. 17 and lasted through Feb. 20.
The rain totals exceeded the two previous storms. Sacramento go 5.13 inches (including 3.21 inches on Feb. 18, setting a record), and Blue Canyon had 18.49 inches.