California Raining: Stormy Weather on the West Coast


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What does the winter hold for California’s rivers this year? Photo: basykes / CC by 2.0

For some, December brings snow and ice, but in the Northwest, this December has brought sandbags and torrential rain.

In California, the fourth storm in a week is heading toward the coast.

It’s beginning to look a lot like flood season, and in Sacramento and Napa, sandbagging was in order as rivers rose.

In Napa, officials handed out 8000 sandbags and issued a flash flood watch. Thankfully, the rivers rose less than expected, and there was not severe flooding.

Over a five day period that ended on December 2nd, residents experienced rainfall of 15 to 20 inches in some areas.

California Mudslides on Burned Hillsides?

On the northern coast, 14 to 16 foot swells led to warnings on the coast. The rains have also brought caution about potential mudslides.

Slopes that have experienced fires and have less vegetation could be more prone to slides in the rainy season, as there is less foliage to slow down the rain that falls on the hillsides.

In southern Oregon and northern California, an additional 1 to 4 inches of rain are expected on Tuesday, with snowfall in the Cascades leading to an additional 1 to 2 feet of snow accumulation.

El Nino changes rainfall patterns, but so far a strong El Nino has not emerged. Photo: David O / CC by 2.0

California’s Winter Storms: What’s Coming Up?

After a year that saw drought scorch much of the United States and after a winter that was warmer than usual, what is in store for California this year? Long term weather forecasting can be a challenge. While it’s easy to see weather systems when they appear on our tracking devices, they’re harder to predict over months. Major climate patterns like the North Atlantic Oscillation are hard to predict more than two weeks in advance. El Nino tends to be a little bit more predictable, and earlier in the year, NOAA predicted that this winter would be an El Nino winter. The presence of El Nino shifts tropical rainfall patterns. This weather pattern tends to occur every one to five years, but a strong El Nino has not occurred since the winter of 1997-1998.

Could Los Angeles receive Seattle’s level of rainfall in the winter of 2012? By mid summer  2012, this still looked like a possibility. After several years of the drier La Nina conditions, rainfall would be a good thing. However, while this winter is expected to be warmer than average in the northwest, a strong El Nino has not yet emerged. It remains to be seen whether a warm, wet winter is coming to damp down California this year.


USA Today. Third Storm in Five Days Drenches West Coast. (2012). Accessed December 3, 2012.

NOAA. Rain Returns to Northern California, Pacific Northwest. (2012). Accessed December 4, 2012.

NOAA. Elusive El Nino Challenges NOAA’s 2012 Winter Outlook. (2012). Accessed December 4, 2012.

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