Sea surface temperature anomalies during May 2018, compared to the 1981-2010 average. Credit: NOAA.

The National Oceanic and Atmospheric Administration has issued an El Niño watch, meaning that conditions are favorable for El Niño conditions to develop in the tropical Pacific Ocean within the next six months.

Why it matters: If an El Niño forms, it would follow one of the most intense such events on record, which teamed up with long-term climate change, to lead to the warmest year ever recorded: 2016. Depending on its exact location in the Pacific and its intensity, the climate phenomenon can reorder weather patterns around the world. On the plus side, it can contribute to increased upper atmospheric winds over the tropical Atlantic, weakening nascent hurricanes and keeping the number of storms lower than they otherwise would be.

Yes, but: Such events can cause droughts and even contribute to political instability as far away as Africa, while sparking deadly flooding in other areas, such as California.

El Niño events also help transport heat from the ocean into the atmosphere, and tend to lead to some of the globe's warmest years. The record warm years of 2015 and 2016 occurred during an intense El Niño event, for example.

NOAA currently forecasts a 50% chance of El Niño developing during the fall, with those odds rising to 65% during the winter. While sea surface temperatures are close to average right now, heat is building up under the surface — a sign that an El Niño may be on its way.

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Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 4:30 p.m. ET: 31,735,542 — Total deaths: 973,443 Total recoveries: 21,798,488Map.
  2. U.S.: Total confirmed cases as of 4:30 p.m. ET: 6,925,840 — Total deaths: 201,617 — Total recoveries: 2,646,959 — Total tests: 96,612,436Map.
  3. Health: CDC director says over 90% of Americans have not yet been exposed to coronavirus — Supply shortages continue to plague testing.
  4. Politics: Poll: 51% of Republicans trust Trump on coronavirus more than the CDC.
  5. Vaccines: Johnson & Johnson begins large phase 3 trial — The FDA plans to toughen standards.
  6. Sports: Less travel is causing the NBA to see better basketball.

Trump says he wants 9 justices in case Supreme Court must decide 2020 election

President Trump told reporters at the White House on Wednesday that part of his urgency to quickly push through a replacement for the late Justice Ruth Bader Ginsburg is that he believes the Supreme Court may have to decide the result of the 2020 election.

Why it matters: Trump claimed at the Republican National Convention that the only way he will lose the election is if it is "rigged," and he has declined to say whether he would accept the results of November's election if he loses to Joe Biden.

"Not enough": Protesters react to no murder charges in Breonna Taylor case

A grand jury has indicted Brett Hankison, one of the Louisville police officers who entered Breonna Taylor's home in March, on three counts of wanton endangerment for firing shots blindly into neighboring apartments.

The state of play: Angering protesters, the grand jury did not indict any of the three officers involved in the botched drug raid on homicide or manslaughter charges related to the death of Taylor.

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