Current ENSO Information
Summary of ENSO Model Forecasts
16 December 2002
Note on interpreting model forecasts
The following graph and table show forecasts made by dynamical and statistical
models for SST in the Nino 3.4 region for nine overlapping 3-month periods.
Note that the expected skills of the models, based on historical performance,
are not equal to one another. The skills also generally decrease as the
lead time increases. Thirdly, forecasts made at some times of the year
generally have higher skill than forecasts made at other times of the year--namely,
they are better when made between June and November than when they are
made between January and May. Differences among the forecasts of the models
reflect both differences in model design, and actual uncertainty in the
forecast of the possible future SST scenario.
Discussion of current forecasts
The set of dynamical and statistical model forecasts issued during late
September and early October shows a range of possible sea surface temperature
conditions for the coming 2 to 9 months (December-January-February 2002-03
through August-September-October 2003). Nearly all models are indicating
a continuation of warm conditions, followed by a slow weakening of the
warmth during the first half of 2003. Most of the models forecast warming
sufficient to be called an El Nino (e.g., warming to 0.6 degrees C or more
above average in the Nino 3.4 region for the January-February-March seasonal
average). A small number are forecasting ENSO conditions in the neutral
category--less than 0.6 degrees C away from normal. The warmest forecast
for the January-February-March period comes from the NASA/NSIPP model [2.11
degrees C above normal), and the coldest one is from the Colorado State
Univ CLIPER calling for SST anomalies of -0.02 degrees C. For March-April-May
2003, 12 of the 16 models still suggest El Nino conditions (0.5 degrees
or more for that season): all except for the Australian POAMA, the ECMWF,
the NOAA/CDC Linear Inverse, and the Colorado State Univ. CLIPER.
|
|
