The El Niño forecasts are part of an ongoing research effort at COLA, and do not represent official forecasts. These forecasts should not be used as the basis of any commercial, policy, or other decisions. They are strictly research tools for advancing the understanding of the ocean-atmosphere system.
The NINO3 time series of the predicted SSTA for three
forecasts initialized on the first day of June, July and August
1997, are shown below. Each forecast is run for 18 months.
The
evolution of all three forecasts are consistent. The model predicts
steady anomalously warm conditions (at least 2ºC) in the eastern Pacific from the
initial state (boreal summer 1997) through the boreal winter of
1997-98. After the boreal winter of 1997-98 the NINO3 anomalies in all
three forecasts decay rapidly to near normal conditions by the boreal
summer of 1998 with rather strong cold conditions by the winter of
1998-99.
| Time evolution of the NINO3 SSTA forecast. The solid red curve corresponds to the forecast initialized in June 1997, the dashed blue curve corresponds to the July 1997 forecast and the dotted green curve corresponds to the August 1997 forecast. |
The ensemble mean (average of all three forecasts) horizontal
structure of the predicted SSTA for the boreal fall of 1997, the
boreal winter of 1997-98, and the boreal spring of 1998 are shown in the
three panels below.
The ensemble mean forecast for fall 1997
calls for relatively warm SSTA throughout much of the equatorial
central and eastern Pacific. There is a small region of cold
anomalies in the western Pacific centered along 5ºN. By the winter of
1997-98, the anomaly in the central Pacific has amplified and there is
some narrowing of the anomaly in the far eastern Pacific. The region
of cold anomalies in western Pacific has expanded further to the west.
Given the behavior this model in simulating the SSTA in the past, the
warm anomaly forecast for winter 97-98 is over 3 standard deviations above
normal reflecting the strength if this current ENSO event. By the
spring of 1998 the rapid cooling seen in the panel above can
be detected. Throughout the central and eastern Pacific the warm
anomaly is less than half that forecast for the previous winter.
| The ensemble mean anomalies in sea surface temperature (SSTA). The top panel shows the predicted ensemble mean averaged from September 1997 to November 1997. The middle panel shows the predicted ensemble mean SSTA averaged from December 1997 to February 1998. The bottom panel shows the ensemble mean averaged from March to May 1998. |
These latest forecasts are consistent with the forecast from the previous period, and indicate that peak El Niño conditions can be expected for the winter of 1997-98. These most recent forecast, however, give somewhat stronger warm anomalies than the previous forecasts and a more rapid decay of the warm event.
