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ENSO Quick
Look IRI ENSO Update / Forecast Technical ENSO Update IRI Probabilistic ENSO Forecast ENSO Prediction Plume Monthly archive ENSO Update15 October 2009SummaryConditions in the equatorial Pacific remain indicative of a weak-to-moderate El Niño. For the Oct-Dec and Nov-Jan seasons there is an approximately 90% probability of maintaining at least weak El Niño conditions, and a 10% probability of returning to ENSO-neutral conditions. Probabilities for El Niño stay above 80% through the Jan-Mar season, decreasing to 50% by Mar-May season and to the climatological probability of 25% by the May-Jul season.General Discussion
Between mid-June and mid-July 2009, the NINO3.4 SST anomaly index rose
to values indicative of the weak El Niño category, where it has
since persisted. Atmospheric conditions show signs of El
Niño, including westerly wind anomalies in the western Pacific
and positive convection anomalies near the dateline. The sub-surface
temperatures have remained above-average over a
large portion of the equatorial Pacific since mid-2009, suggesting the
possibility for further development of the oceanic aspects of El Niño.
Between July and mid-October, temperatures at the surface and sub-surface
have not changed significantly, but wind anomalies in the western Pacific have
been intermittently reinforcing the event, as they are doing currently.
Continuation of these wind anomalies may lead to further development.
Whether the event strengthens or not, the El Niño conditions are
expected to persist through the end of the calendar year and possibly
a few additional months. |
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