California and La Nina

During December 1999, the cold sea surface temperature anomalies (SSTAs) that characterize La Nina continued throughout the tropical Pacific. The following figure shows the observed SSTAs (degrees C) over the tropical Pacific durnig December 1999 (from the TAO/TRITON moorings).
December 1999 SST Anomalies

The cold episode has strengthened during the past few months. The average SSTAs over an area of the tropical Pacific called the Nino region (5N-5S; 150W-90W) have continued to decrease and are similar to the values observed in December 1998.

Since 1947 there have been 9 major La Nina events. These occurred in the years:
    1949/1950
    1954/1955
    1964/1965
    1970/1971
    1973/1974
    1975/1976
    1988/1989
    1995/1996
    1998/1999

During these La Ninas, the United States has seen significant changes in normal precipitation and temperature patterns

Precipitation Anomalies from November to March During La Nina Years Versus 1950-1995 Longterm Average

1949-1950	1954-1955	1964-1965
1970-1971	1973-1974	1975-1976
1988-1989	1995-1996	1998-1999

Standardized Precipitation Anomalies from November to March During La Nina Years Versus 1950-1995 Longterm Average

1949-1950	1954-1955	1964-1965
1970-1971	1973-1974	1975-1976
1988-1989	1995-1996	1998-1999

(2) Insert images from Larry here; show California station data of El Ninos vs. La Ninas

1998/1999 was a strong La Nina year

What did the circulation of the atmosphere look like for 1998-1999? 1998-1999 La Nina 500mb Hov

1998-1999 La Nina 500mb Height Anomalies

1999-2000 is another La Nina winter. What does the atmospheric circulation look like so far? 1999-2000 La Nina 500mb Height Anom

1999-2000 La Nina 250mb u-wind anomalies