Saturday, January 10, 2009

2009: La Niña Returns?

So far the winter has been extremely dry out here, with only a dusting of snow left up on the nearby mountains and nothing on the valley bottom. NOAA weather scientists believe that a weak La Niña may be forming, and in our area, a La Niña means less precipitation. 

La Niña is associated with unusually cold ocean temperatures in the Equatorial Pacific. These ocean temperatures impact temperatures globally for up to two years. During a La Niña, the easterly trade winds are stronger than normal, allowing colder water to upwell along the equator and western coast of South America. These colder water temperatures can be as much as 7 degrees F below normal.

In the U.S., La Niña causes drier than normal conditions in the Southwest, Central Plains, and Southeast; and wetter, cooler conditions in the Pacific Northwest. In our area, we hear news reports about places less than one hundred miles to the north that are receiving wonderful snowfall. But we are just far enough below the invisible line that we aren't benefiting from an excess of precipitation. We've been dry for the last couple of years, so it's not great to be getting a La Niña.

La Niña is part of a natural cycle, alternating with neutral conditions and El Niño, when the ocean temperatures in the Equatorial Pacific are warmer than normal. During El Niño years, climate is often the reverse of La Niña conditions.

So I guess we'll just have to do the best we can for now and hope that this La Niña will be weak and soon end. The intensity of La Niña and El Niño events can vary a great deal. If you'd like to learn more about this weather phenomenon, check out the NOAA website.


The Incredible Woody said...

After several years of drought (To the extent that cities were worried about the water supply!), we have had enough rain lately to make a person stir crazy. The lakes and reservoirs in my area are finally full again so I'd send you some of our rain if I could:)

Caroline said...

We are very dry down here in Central California, too. Usually at this time of year we have a big seasonal pond out in our front pasture where our dog loves to play. So far, we don't have a puddle...sigh.

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