The pattern of El Niño has changed dramatically in recent years, according to the first seasonal record distinguishing different types of El Niño events over the last 400 years.

A new category of El Niño has become far more prevalent in the last few decades than at any time in the past four centuries. Over the same period, traditional El Niño events have become more intense.

This new finding will arguably alter our understanding of the El Niño phenomenon. Changes to El Niño will influence patterns of precipitation and temperature extremes in Australia, Southeast Asia and the Americas.

Some climate model studies suggest this recent change in El Niño “flavours” could be due to climate change, but until now, long-term observations were limited.

EL NIÑO/SOUTHERN OSCILLATION (ENSO)
DIAGNOSTIC DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP/NWS
and the International Research Institute for Climate and Society
11 July 2019

ENSO Alert System Status: El Niño Advisory

Synopsis:  A transition from El Niño to ENSO-neutral is expected in the next month or two, with ENSO-neutral most likely to continue through Northern Hemisphere fall and winter.

During June, El Niño was reflected in the continued presence of above average sea surface temperatures (SSTs) across the central equatorial Pacific Ocean [Fig. 1]. However, SST anomalies across most of the eastern Pacific decreased during the month. The latest weekly ENSO indices were +0.9°C in Niño-4 and +0.6°C in Niño-3.4, with smaller departures in the Niño-3 and Niño-1+2 regions [Fig. 2]. Upper-ocean subsurface temperatures (averaged across 180°-100°W) were above average at the beginning of June, but returned to near average by end of the month [Fig. 3], as anomalously cool waters expanded at depth [Fig. 4]. Weakly suppressed tropical convection continued over Indonesia, while weakly enhanced convection persisted near the Date Line [Fig. 5]. Low-level wind anomalies were near average over the tropical Pacific Ocean, and upper-level wind anomalies were westerly over the far eastern Pacific. The traditional and equatorial Southern Oscillation Indices were slightly negative. Overall, oceanic and atmospheric conditions were consistent with a weakening El Niño.

The latest plume of North American Multi-model Ensemble forecasts of the Niño-3.4 index [Fig. 6] shows a rapid transition toward ENSO-neutral by the late Northern Hemisphere summer, remaining neutral through fall and winter. Due to this model guidance and recent observations, the forecast consensus also favors a transition to ENSO-neutral during the next few months. In summary, a transition from El Niño to ENSO-neutral is expected in the next month or two, with ENSO-neutral most likely to continue through Northern Hemisphere fall and winter (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).

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 are also updated monthly in the Forecast Forum of CPCs Climate Diagnostics Bulletin. Additional perspectives and analysis are also available in an ENSO blog. The next ENSO Diagnostics Discussion is scheduled for 8 August 2019.

To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message to: ncep.list.enso-update@noaa.gov.

Climate Prediction Center
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