ENSO Quick
Look
IRI ENSO Update / Forecast
Technical
ENSO Update
IRI Probabilistic ENSO
Forecast
ENSO Prediction Plume
Monthly
archive
ENSO Update
20 May 2010
Summary
El Niño conditions that prevailed from June 2009 through April 2010
in the equatorial Pacific dissipated during early May, resulting in
ENSO-neutral conditions in mid-May.
For the May-July season in progress, there is an approximately 80% probability
of maintaining neutral ENSO conditions, a 13% probability for developing La
Niña conditions, and a 7% probability for a return to El Niño
conditions. Probabilities for La Niña conditions increase
to 42% from the August-October season through the remainder of 2010.
General Discussion
By mid-May, the NINO3.4 SST anomaly index decreased to values
indicative of neutral ENSO, following the moderate(+) El Niño levels
observed from November 2009 through January 2010.
Since early March zonal wind anomalies in the equatorial Pacific have
returned to near-average following the strong westerly anomalies during
northern winter 2009/10. Subsurface heat content has returned from the well above-average
levels seen during much of 2009 and early 2010, to near-average and recently
developing below-average levels as negative sub-surface sea temperatures replace
the previously above-average temperatures that dominated during the
El Niño.
Out of a large set of dynamical and statistical forecast models,
80% indicate maintenance of ENSO-neutral conditions during the May-June-July
season currently in progress, while about 13% indicate development of
La Niña conditions. Overall, based on model
forecasts and current observations of the ocean surface and subsurface,
for the coming July-September season the probability for La Niña
conditions is estimated at 40%, and for ENSO-neutral conditions approximately
57%. Probabilities for a return to El Niño conditions are 5% or less
from June-September through the rest of 2010.
Top of Page
|
 | |
|
|
