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This is a catalog of
nationwide average "winter" temperature and precipitation anomalies for
previous El Niño and La Niña events. It also has the average for all
events, weak events, moderate events and strong events.
It
cannot be stressed strongly enough that this is a climatological analysis
and not a forecasting tool. This is especially true for the averages of
different strength events which are made up of what are a very broad range
of conditions; some that are decidedly atypical.
The
Oceanic Niño Index (ONI)
is used to identify El Niño (warm) and La Niña (cool) events in the
tropical Pacific. The ONI is the running 3-month mean SST anomaly for the
Niño 3.4 region (i.e.,
5oN-5oS, 120o-170oW).
Events are defined as 5 consecutive months at or above the +0.5o anomaly
for warm (El Niño) events and at or below the -0.5 anomaly for cold (La
Niña) events. The threshold is further broken down into Weak (with a 0.5
to 0.9 SST anomaly), Moderate (1.0 to 1.4) and Strong (≥ 1.5) events. For
the purpose of this report for an event to be weak, moderate or strong it
much have equaled or exceeded the threshold for at least 3 months.
*A period of November - March was chosen as "winter" for this study
because approximately 85% of the California rainfall is during that
period.
El Niño Events:
Weak: 51-52, 63-64,
68-69, 69-70, 76-77, 77-78, 04-05, 06-07
Moderate: 86-87, 87-88, 94-95,
02-03
Strong: 57-58, 65-66, 72-73, 82-83, 91-92, 97-98, 09-10
La Niña Events:
Weak: 50-51, 56-57, 62-63, 67-68,
71-72, 74-75, 84-85, 95-96, 00-01
Moderate: 54-55, 64-65, 70-71, 98-99,
99-00, 07-08, 10-11
Strong: 55-56, 73-74, 75-76, 88-89
El Niño (Warm Event)
Anomalies:
Winter (November, December, January, February, March) Impacts
| El Niño
Precipitation |
Average -
All
ONI ≥
+0.5
|
| 1951-52 |
1957-58 |
1963-64 |
1965-66 |
1968-69 |
 |
 |
 |
 |
 |
| 1969-70 |
1972-73 |
1976-77 |
1977-78 |
1982-83 |
 |
 |
 |
 |
 |
| 1986-87 |
1987-88 |
1991-92 |
1994-95 |
1997-98 |
 |
 |
 |
 |
 |
| 2002-03 |
2004-05 |
2006-07 |
2009-10 |
|
 |
 |
 |
 |
|
|
| |
Average - Weak
ONI= +0.5 to +0.9
|
| 1951-52 |
1963-64 |
1968-69 |
1969-70 |
1976-77 |
|
|
|
|
|
|
| 1977-78 |
2004-05 |
2006-07 |
|
|
|
|
|
|
|
|
|
| |
Average - Moderate
ONI=
+1.0
to +1.4
 |
| 1986-87 |
1987-88 |
1994-95 |
2002-03 |
|
|
|
|
|
|
|
|
| |
Average - Strong
ONI= ≥ +1.5
|
| 1957-58 |
1965-66 |
1972-73 |
1982-83 |
1991-92 |
|
|
|
|
|
|
| 1997-98 |
2009-10 |
|
|
|
|
|
|
|
|
|
|
| El Niño
Temperature |
Average -
All
ONI ≥
+0.5
 |
| 1951-52 |
1957-58 |
1963-64 |
1965-66 |
1968-69 |
 |
 |
 |
 |
 |
| 1969-70 |
1972-73 |
1976-77 |
1977-78 |
1982-83 |
 |
 |
 |
 |
 |
| 1986-87 |
1987-88 |
1991-92 |
1994-95 |
1997-98 |
 |
 |
 |
 |
 |
| 2002-03 |
2004-05 |
2006-07 |
2009-10 |
|
 |
 |
 |
 |
|
|
| |
Average - Weak
ONI= +0.5 to +0.9
 |
| 1951-52 |
1963-64 |
1968-69 |
1969-70 |
1976-77 |
|
|
|
|
|
|
| 1977-78 |
2004-05 |
2006-07 |
|
|
 |
|
|
|
|
|
| |
Average - Moderate
ONI=
+1.0
to +1.4
 |
| 1986-87 |
1987-88 |
1994-95 |
2002-03 |
|
 |
 |
 |
 |
|
|
| |
Average - Strong
ONI= ≥ +1.5
|
| 1957-58 |
1965-66 |
1972-73 |
1982-83 |
1991-92 |
 |
 |
 |
 |
 |
| 1997-98 |
2009-10 |
|
|
|
 |
 |
|
|
|
|
| La Niña
Precipitation |
Average -
All
ONI ≤
-0.5
 |
| 1950-51 |
1954-55 |
1955-56 |
1956-57 |
1962-63 |
 |
 |
 |
 |
 |
| 1964-65 |
1967-68 |
1970-71 |
1971-72 |
1973-74 |
 |
 |
 |
 |
 |
| 1974-75 |
1975-76 |
1984-85 |
1988-89 |
1995-96 |
 |
 |
 |
 |
 |
| 1998-99 |
1999-00 |
2000-01 |
2007-08 |
2010-11 |
 |
 |
 |
 |
 |
|
| |
Average - Weak
ONI=
-0.5 to -0.9
 |
| 1950-51 |
1956-57 |
1962-63 |
1967-68 |
1971-72 |
|
|
|
|
|
|
| 1974-75 |
1984-85 |
1995-96 |
2000-01 |
|
|
|
|
|
|
|
|
| |
Average - Moderate
ONI=
-1.0
to -1.4
 |
| 1954-55 |
1964-65 |
1970-71 |
1998-99 |
1999-00 |
|
|
|
|
|
|
| 2007-08 |
2010-11 |
|
|
|
|
|
|
|
|
|
|
| |
Average - Strong
ONI
≤
-1.5
 |
| 1955-56 |
1973-74 |
1975-76 |
1988-89 |
|
|
|
|
|
|
|
|
| La Niña
Temperature |
Average -
All
ONI ≤
-0.5
 |
| 1950-51 |
1954-55 |
1955-56 |
1956-57 |
1962-63 |
 |
 |
 |
 |
 |
| 1964-65 |
1967-68 |
1970-71 |
1971-72 |
1973-74 |
 |
 |
 |
 |
 |
| 1974-75 |
1975-76 |
1984-85 |
1988-89 |
1995-96 |
 |
 |
 |
 |
 |
| 1998-99 |
1999-00 |
2000-01 |
2007-08 |
2010-11 |
 |
 |
 |
 |
 |
|
| |
Average - Weak
ONI=
-0.5 to -0.9
 |
| 1950-51 |
1956-57 |
1962-63 |
1967-68 |
1971-72 |
|
|
|
|
|
|
| 1974-75 |
1984-85 |
1995-96 |
2000-01 |
|
|
|
|
|
|
|
|
| |
Average - Moderate
ONI=
-1.0
to -1.4
 |
| 1954-55 |
1964-65 |
1970-71 |
1998-99 |
1999-00 |
|
|
|
|
|
|
| 2007-08 |
2010-11 |
|
|
|
|
|
|
|
|
|
|
|
Average - Strong
ONI
≤
-1.5
 |
| 1955-56 |
1973-74 |
1975-76 |
1988-89 |
|
|
|
|
|
|
|
|
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