ENSO-neutral conditions still reign as of the beginning of the month, but we’re starting to see some clearer signs of the development of El Niño.
Forecasters estimate that El Niño conditions will develop in the next few months, and there’s a 70-75% chance El Niño will be present through the winter. Most computer models are currently predicting a weak El Niño event.
Over the past several weeks, surface temperature anomalies (difference from the long-term average) have gradually increased across much of the tropical Pacific. All four of the Niño-monitoring-region temperatures are now above average.
Animation showing sea surface temperature departure from the long-term average from August through early October 2018. Graphic by climate.gov; data from NOAA’s Environmental Visualization Lab.
The temperature in the Niño3.4 region (our primary metric for monitoring El Niño’s development) was 0.7°C above the long-term average in the latest weekly measurement. Yep, that’s above the El Niño threshold of 0.5°C, but we’ll need the monthly temperature in the Nino3.4 region to average above that threshold, plus an expectation that it will stay above, and indications that the atmosphere is responding to the change in the ocean before we’d declare El Niño.