Saturday, November 19, 2011

La Nina Update

The La Nina today is still very much present and remains east-based. This means, in a situation only affected by the ENSO process (La Nina/El Nino), the East US would be cooler than normal. However, there are many more variables that affect temperatures and precipitation. At this point, as previously stated, the coldest anomalies are situated in the eastern portions of the ENSO monitoring areas.
Something recently discovered by our team is the Southern Oscillation Index (SOI). When the SOI is positive, it is indicative of a La Nina. When the SOI is in a negative phase, an El Nino is usually present. Last year, SOI values were as high as 27.1, showing a big presence of a La Nina. However, the October SOI values turned out at 7.3 units. While it is expected that the values will be lower as we are in a 'double dip' La Nina, these are very modest values that indicate this La Nina may not be as strong as originally thought. Unless the SOI goes to higher values soon, we may have to revise our winter forecast.

Note: We may have to revise portions of our winter forecast as per the new CPC outlooks and teleconnection information that is looking somewhat unfavorable for some people.

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