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ENSO Alert System Status: Not Active
Synopsis: There is a ~65% chance of ENSO-neutral during Northern Hemisphere summer 2020, with chances decreasing through the autumn (to 45-50%).
During April 2020, positive sea surface temperature (SST) anomalies weakened and were near zero by the end of the month. All of the Niño indices decreased during the month, with the latest weekly Niño index values near +0.2°C. Equatorial subsurface temperatures (averaged across 180°-100°W) declined further and were below average, due to the eastward expansion of below-average subsurface temperatures into the eastern Pacific. Also during the month, low-level wind anomalies were easterly across the central and east-central Pacific, while upper-level wind anomalies were westerly over the central and eastern portions of the basin. Tropical convection was near average around Indonesia and suppressed over the Date Line. Overall, the combined oceanic and atmospheric system remained consistent with ENSO-neutral.
The majority of models in the IRI/CPC plume favor ENSO-neutral (Niño-3.4 index between -0.5°C and +0.5°C) through the Northern Hemisphere autumn, though considerable spread is evident at longer lead times. Niño 3.4 index values are expected to decrease through the remainder of the Northern Hemisphere spring and into the summer; with the possibility of below-average temperatures becoming more established toward the latter half of the year. The consensus of forecasters favors ENSO- neutral conditions through the summer and fall, and slightly tilts toward La Niña at the end of the year (~45% chance). There is a ~10% chance of El Niño from the summer through the end the year. In summary, there is a ~65% chance of ENSO-neutral during Northern Hemisphere summer 2020, with chances decreasing through the autumn (45-50%; click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).