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Environment & Science

4 things to know about this week's storms

 The Los Angeles Aqueduct carries water from the snowcapped Sierra Nevada Mountains.
The Los Angeles Aqueduct carries water from the snowcapped Sierra Nevada Mountains.
David McNew/Getty Images

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There’s been a lot of hopeful talk about the upcoming storms lifting us out of the five-year drought, but not all storms are a good thing for a parched California.

According to a recent Wired article, warm rains expected this weekend could negatively affect our snowpack, melting a much-needed and concentrated water supply that would be released into rivers and oceans during the summer. These rains could also mean flooding and landslides in the areas including the Sierra Nevada.

So will the rain help break the state’s drought? Marty Ralph is the director of the Center for Western Weather and Water Extremes at the Scripps Institution of Oceanography at UC San Diego. He spoke with Alex Cohen to give a better picture of what the rain means for California.

Here are four takeaways from the conversation with things to know about California's storms.

1. This weather system we're seeing is called an atmospheric river.

MARTY RALPH: It's a region in the atmosphere that's loaded with water vapor and has strong horizontal winds. It transports amazing amounts of water vapor — 20 times the amount of liquid the Mississippi transports. When that hits the coast or mountains, it can produce heavy rain and snow. 

2. Warmer storms mean less snow, and more flooding.

RALPH: The storm this weekend is forecast to have very high snow levels. That means the snow will occur in the higher parts of the mountains, but the middle parts will get rain, contributing to heavy runoff in the rivers so there are some flood warnings. 

3. We're prepared for flooding...depending on how long storms last.

RALPH: The major reservoirs in the Central Valley are at levels where they're prepared for flooding-like storms to occur. If we get a series of atmospheric storms, over a week or more, that capacity to absorb the crest of the floods will be diminished as the reservoirs fill up, but that has yet to be seen.

4. Warm or cold, these storms could bring some drought relief.

RALPH: The drought is ameliorated by having rain and snow. It's clear that the northern half of California has come out of drought conditions over the last nine months. Southern California is still a bit dry and these storms could help alleviate that in the next week or so. In the case of flooding, when water needs to be released from dams, that water goes to the ocean. However, it has environmental benefits. But ultimately, if we get into too high a flow condition, that water has to be released and we may have been able to keep it. 

To listen to the full interview, click on the blue media player above.