There’s been much ado about a strong El Niño, but less is heard about the appearance of a sister anomaly Atlantic Niña.  What happens to summer storm activity when both are on stage?  Ben Cost does a good job of pulling together the implications in his NY Post article El Niño’s sister La Niña has arrived in the Atlantic — here’s what that means for summer weather.  Excerpts in italics with my bolds and added images.

The extremely strong El Niño brewing in the South Pacific isn’t the only unusual weather pattern on the horizon.  Meteorological experts warn that the oceanic anomaly’s sister —  Atlantic Niña — could be rearing its head in the tropical part of The Pond, potentially helping curtail the number of storms we’ll see this season, according to Severe Weather Europe.

This climate pattern is similar to La Niña — the cold phase of the El Niño Southern Oscillation (ENSO) — in that both cause temperature plunges below average. The difference is that this big chill affects the eastern equatorial Atlantic Ocean instead of the central and eastern equatorial Pacific, potentially altering wind and rainfall across the tropics, per Climate.org.

Should surface temps on the Atlantic Ocean hover at 0.9 degrees Fahrenheit below average for at least two overlapping seasons, this could mark just the sixth Atlantic Niña in the last four decades.

The sibling anomaly El Niño, meanwhile, causes preternaturally warm temperatures on the Pacific Ocean’s surface with forecasters predicting that this particular version could be up to 6.5 degrees warmer than average, potentially making it the strongest El Niño on record.

Despite being polar opposites on the thermometer, these temp-affecting twins are “perfectly aligned in their atmospheric impact,” long-range forecaster Andrej Flis wrote for Severe Weather Europe.

This means that both will help curb hurricanes — but in different ways. El Niño produces high wind shear and sinking dry conditions over the Atlantic and Caribbean — where wind shear is already the second highest on record for July — potentially nipping the storm systems in the bud, according to Weather.com.

This prophylactic effect is evident in the dramatic reduction in the number of forecasted storms, which currently totals just nine, according to Colorado State University’s tropical meteorology project team.

Of these, only four are projected to become hurricanes, while just one will attain Category 3 status or stronger, marking five fewer storms and three fewer hurricanes than an average season.

El Niño’s sister system, meanwhile, literally throws cold water on cyclones. Cooler ocean temps in the Atlantic prevent the heat and moisture buildup required for thunderstorm buildup, according to The Conversation.

It will be interesting if these sibling systems have double the preventive impact come hurricane season.

So far, Tropical Storm Arthur was the only named storm to form in the Atlantic Basin before July 17 — one fewer than during and average year, Gizmodo reported.

And while it caused flash flooding and tornadoes to lash the south, this so-called superstorm fizzled before long.   Meanwhile, there are no signs of an Atlantic hurricane; the first one usually forms by August 11.