The next ENSO Diagnostic Discussion is scheduled for today, May 14, 2026. The Climate Prediction Center publishes the document on the second Thursday of each month. The April 9 print had ENSO-neutral conditions in place through April-June 2026 at 80 per cent probability, with El Nino likely to emerge in May-July at 61 per cent probability and persist through at least the end of 2026. It also flagged the possibility of a very strong El Nino — a Nino-3.4 index value at or above +2.0 degrees Celsius during the autumn — at a 1-in-4 probability, contingent on continued westerly wind anomalies over the western equatorial Pacific. [1] The paper's May 13 piece framed the super-El-Nino probability as already at 50-50 in some assessments. Today's print is the test.

The case for the super-El-Nino probability moving up is in the subsurface ocean. The April Diagnostic Discussion noted that the equatorial subsurface temperature index, averaged between 180 and 100 degrees west longitude, had increased for the fifth consecutive month. Above-average subsurface temperatures extended across the Pacific from the western boundary to the eastern. [1] The subsurface heat content is the reservoir from which El Nino events are built; a five-month accumulation pointing east is the standard precursor signature. The European Centre for Medium-Range Weather Forecasts model, which NBC News cited in its May 6 coverage of the developing event, has been projecting a potential anomaly of around +3 degrees Celsius in the central equatorial Pacific by autumn 2026. [2] Three-degree-plus anomalies are super-El-Nino territory. If the central tendency of the model ensembles is moving up, the CPC's discussion may follow.

The case for the probability holding rather than moving up is in the atmospheric coupling. The April print noted that westerly wind anomalies were "observed over the western equatorial Pacific at low levels, and were evident over the eastern Pacific at high levels." Convection was near-average over the dateline with suppressed convection over western Indonesia. [1] These are the standard atmospheric indicators of an El Nino in formation. But the coupling has not yet locked in. The atmospheric circulation has not yet decoupled from a La Nina-like configuration completely; the eastern equatorial Pacific (Nino-1+2) anomaly was +0.6 degrees in April, while the Nino-3.4 region was -0.2 degrees — a pattern called "modoki" precursor that can produce moderate El Nino events but does not always produce strong ones. The 1-in-4 super probability the April print named is contingent precisely on whether the westerly wind anomalies continue. If they weaken in May, the probability declines. If they strengthen, the probability moves up.

The International Research Institute for Climate and Society at Columbia, which co-issues the Diagnostic Discussion with the CPC, gave a mid-April assessment with El Nino probabilities for the May-July season at 70 per cent — higher than the CPC's 61 per cent — and persistence probabilities through the boreal winter forecast period at 88 to 94 per cent. [3] The IRI's plume is structurally more bullish on El Nino formation than the CFSv2 ensemble that anchors the CPC's communications. Today's print will tell whether the CPC has narrowed the gap between the two assessments.

What today's print will mean operationally depends on whether the CPC moves from "watch" to "advisory" status. The April print held the alert system at "Final La Nina Advisory / El Nino Watch." The Watch is issued when conditions are favourable for development within six months. The Advisory is issued when El Nino conditions are observed and expected to continue. The threshold for an Advisory is a Nino-3.4 monthly index value at or above +0.5 degrees Celsius coupled with consistent atmospheric anomalies and an expectation of three-month persistence. [4] The April Nino-3.4 monthly value was -0.2 degrees. Today's relevant value is the late-April-into-early-May reading. If that reading has crossed +0.5 degrees, the operational status changes today. If it has not, the Watch holds for another month.

The downstream consequences the climate community will be watching for are in the hurricane outlook NOAA will release on May 21. El Nino conditions reduce Atlantic hurricane activity by increasing vertical wind shear over the Caribbean and tropical Atlantic, which disrupts tropical cyclone formation. A super El Nino would suppress Atlantic activity strongly. But the Atlantic sea-surface temperatures going into June are running well above the 1991-2020 baseline; the Colorado State University outlook on April 9 projected 13 named storms, 6 hurricanes, 2 major hurricanes — a slightly-below-average season — with the explicit note that a developing El Nino was the suppressing factor offsetting record-warm Atlantic SSTs. [5] If today's print upgrades the El Nino probability, the May 21 outlook may come in lower than CSU's. If today's print does not, the Atlantic-warmth signal may dominate. The two assessments meet next Wednesday.

For the lost-science thread the paper has been carrying, today's print is one of the cleanest tests of federal scientific capacity that the calendar will produce this quarter. The Diagnostic Discussion is a monthly product. It has a deadline. It has a defined methodology and a published forecast format. The Climate Prediction Center has been issuing it on the second Thursday of every month for years. The question this edition is asking is not whether the institution will produce the document — they will — but whether the analysis will move with the data, and whether the document will name the super-El-Nino probability change at the resolution the underlying signals justify. If the discussion buries the super-event probability in caveat, the capacity test is failed. If it states the probability cleanly and gives the operational alert change cleanly, the capacity test is passed.

The Diagnostic Discussion is also a reminder of how this kind of forecast works at the production level. The discussion is the product of approximately twenty-five climate scientists across NOAA's National Weather Service, the Climate Prediction Center proper, the National Centers for Environmental Prediction, and the IRI. They draft the language collaboratively over the week before the second Thursday. They review the model ensembles — the NMME, the CFSv2, the IRI plume, the ECMWF SEAS5. They sign off on the synopsis paragraph as a group. That is the institution.

The document will publish at noon Eastern Time today. The paper will hold the analysis to two questions: did the super-El-Nino probability move from 1-in-4, and did the alert status move from Watch to Advisory.

-- DARA OSEI, London