Ready or not, atmospheric river on its way
They’re called “atmospheric rivers,” and we’re about to be swept beneath one. Maybe two.
If forecasts are correct, by this time next Saturday (Jan. 14), our region will have received 9 or even 10 inches of rain as two of those “rivers” flow above our region.
That’s roughly the same amount of rain we got in all of 2013. It’s two inches more than we got in 2014. It’s a lot of water, enough to fill a medium-size reservoir. Are you ready for it?
That’s entirely rhetorical question. Ready or not, the U.S. Weather Service, Accuweather, The Weather Company and others all say it’s coming and, as usual, there’s nothing you can do about it. Except, perhaps, get out of the way.
If you live in a low-lying area near a river, stream or usually dry creekbed, be prepared to move – and quickly. We’re talking specifically about those who live along Dry Creek in Modesto and Orestimba Creek in Merced County – they’re the most notorious streams for flooding. In the case of Orestimba Creek, people have died trying to drive across flooded roads. If you see water flowing over a road, turn around.
The Tuolumne, Stanislaus and Merced rivers are controlled by dams, so catastrophic flooding is less likely. But the rivers will become exceedingly dangerous; it’s best to stay at a safe distance. The Tuolumne, in particular, is already up as Turlock Irrigation District releases some water to make room for more.
If you live beneath an especially steep (20 degrees) hillside with disturbed or bare dirt – either from planting of new trees or if there’s been a recent burn – then there’s a chance some of that dirt might come sliding down the hill. Not to sound alarmist, but it would be best not to be in its path.
County officials met Friday to map out emergency plans; the irrigation districts are modeling flows to ensure our reservoirs won’t overflow.
But what about your roof? If it has a leak, better have a tarp handy. If your yard has a tendency to flood, fill some sandbags to block water from getting inside.
And don’t let your concerns end when the rain stops.
Vance Kennedy, a retired soil and water scientist with the U.S. Geological Survey, has been warning about severe runoff and its consequences for the last three years. He told The Bee last year that a “real gulley-washer” could send significant topsoil flowing down hillsides. As the water moves downhill, it dissolves more soil and picks up weight, allowing the stream to cut more deeply into hillsides and carry away even more. By the time it gets to the bottom, the stream could be laden with clay, gravel and debris which will find its way into our rivers.
Eventually, as the flow slows, the soil and debris drops to the bottom. That raises the stream bed and can lead to increased likelihood of future flooding.
Our region has seen such flows before. In 1997, the region was flooded by the so-called “pineapple express,” whose warm rain melted Sierra snow and quickly filled our reservoirs almost to capacity. There is less snow in the Sierra this year and the rain is expected to be at least marginally colder.
Regardless, we’re about to get soaked by an atmospheric river. Caution and preparation will make certain it doesn’t wash us away.
This story was originally published January 6, 2017 at 2:24 PM with the headline "Ready or not, atmospheric river on its way."