LATEST EL NINO NEWS.

ENSO Alert System Status: El Niño Advisory

Synopsis: El Niño is expected to strengthen and last through the Northern Hemisphere Winter 2009-2010.
A weak El Niño was present during July 2009, as monthly sea surface temperatures (SST) departures ranged from +0.5°C to +1.5°C across the equatorial Pacific Ocean, with the largest anomalies in the eastern half of the basin (Fig. 1). Consistent with this warmth, all of the Niño-region SST indices were between +0.6°C to +1.0°C throughout the month (Fig. 2). Subsurface oceanic heat content (average temperatures in the upper 300m of the ocean, Fig. 3) anomalies continued to reflect a deep layer of anomalous warmth between the ocean surface and thermocline (Fig. 4). Also, convection was suppressed over Indonesia and enhanced across the western Pacific and near the International Date Line. In addition, developing El Niño’s often feature westerly wind bursts over the western equatorial Pacific, such as the one which occurred at the end of July (Fig. 5). These oceanic and atmospheric anomalies reflect El Niño.
A majority of the model forecasts for the Niño-3.4 SST index (Fig. 6) suggest El Niño will continue to strengthen. While there is disagreement on the eventual strength of El Niño, nearly all of the dynamical models predict a moderate-to-strong El Niño during the Northern Hemisphere Winter 2009-10. A strengthening El Niño during the next few months is also suggested by the recent westerly wind event in the western equatorial Pacific, which can lead to additional anomalous warmth across the central and east-central equatorial Pacific during the next two months. Therefore, current conditions and model forecasts favor the continued development of a weak-to-moderate strength El Niño into the Northern Hemisphere Fall 2009, with the likelihood of at least a moderate strength El Niño (3-month Niño-3.4 SST index of +1.0°C or greater) during the Northern Hemisphere Winter 2009-10.
Expected El Niño impacts during August-October 2009 include enhanced precipitation over the central and west-central Pacific Ocean and the continuation of drier than average conditions over Indonesia. Temperature and precipitation impacts over the United States are typically weak during the Northern Hemisphere Summer and early Fall, and generally strengthen during the late Fall and Winter.
This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions.

EL NINO WATCH.

EL NIÑO/SOUTHERN OSCILLATION (ENSO)
DIAGNOSTIC DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP
4 June 2009

ENSO Alert System Status: El Niño Watch




Synopsis: Conditions are favorable for a transition from ENSO-neutral to El Niño conditions during June - August 2009.
The recent oceanic and atmospheric anomalies are consistent with ENSO-neutral conditions, but also reflect the evolution towards a potential El Niño. Most dynamical models, including the NCEP Climate Forecast System, predict the onset of El Niño during June - August 2009. Current observations, recent trends, and the dynamical model forecasts indicate that conditions are favorable for a transition from ENSO-neutral to El Niño conditions during June - August 2009.These surface and subsurface oceanic anomalies typically precede the development of El Niño.
ENSO-neutral conditions persisted across the equatorial Pacific Ocean during May 2009. However, sea surface temperature (SST) anomalies increased for the fifth consecutive month, with above-average temperatures extending across the equatorial Pacific Ocean by the end of May (Fig. 1). Accordingly, the latest weekly SST indices ranged between +0.4o to +0.5°C in all four Niño regions (Fig. 2). Subsurface oceanic heat content anomalies (average temperatures in the upper 300m of the ocean, Fig. 3) also continued to increase in response to a large area of above-average temperatures (+2° to +4°C) near thermocline depth (Fig. 4). From early 2007 through April 2009, enhanced low-level easterly winds persisted near the Date Line, interrupted only briefly by Madden-Julian Oscillation (MJO) activity. However, during May 2009, both the lower-level equatorial winds were near-average in that region despite the absence of the MJO. Also, suppressed convection expanded westward along the equator from the Date Line to Indonesia. There continues to be considerable spread in the model forecasts for the Niño-3.4 region (Fig. 5). All statistical models predict ENSO-neutral conditions will continue for the remainder of 2009.
This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Forecasts for the evolution of El Niño/La Niña are updated monthly in the Forecast Forum section of CPC's Climate Diagnostics Bulletin.