Enjoying Cooler Weather?

We finally broke out of the 100+ F (38+ C) weather a couple of weeks to more mild days in the 90s (32+ C). But these past few days have been unseasonably cool--yesterday, for instance, was 10 degrees less than normal for this time per year. It is a welcome change, although it may presage an early fall. But SW Idaho is not the only place experiencing cooler weather. The New Scientist reported on August 19: "Part of the Atlantic is cooling at record speed and nobody knows why." From the lede:

Over the past three months, the shift from hot to cool temperatures in the equatorial Atlantic Ocean has happened at record speed. This emerging “Atlantic Niña” pattern comes just ahead of an expected transition to a cooler La Niña in the Pacific Ocean, and these back-to-back events could have ripple effects on weather worldwide.

The article continues:

    The swing towards cooler temperatures in both oceans is a welcome change after more than a year of record heat at land and sea, largely driven by the rise in greenhouse gas emissions and a warm El Niño pattern in the tropical Pacific Ocean that developed in mid-2023.

    “We are starting to see that the global mean ocean temperatures are going down a bit,” says Pedro DiNezio at the University of Colorado Boulder. According to the US National Oceanic and Atmospheric Administration (NOAA), global sea surface temperatures this past July were slightly cooler than in July 2023 – ending a 15-month streak of record-high average ocean temperatures.

The article also lists some of the possible results of the interaction between the two ocean patterns:

    The two potential La Niñas are likely to influence weather patterns around the world due to their effects on temperature and humidity. A Pacific La Niña is generally associated with dry weather in the western US and wet weather in East Africa, while an Atlantic Niña tends to reduce precipitation in Africa’s Sahel region and boost it in parts of Brazil. The two La Niñas could also have opposing influences on the ongoing Atlantic hurricane season: the Pacific La Niña is expected to increase the likelihood of Atlantic hurricanes when it arrives in September, but the Atlantic La Niña may weaken certain conditions, such as atmospheric wave activity, required for hurricanes to form.

    The cycles could also influence each other directly. Exactly how is challenging to predict, but there is reason to think the Atlantic La Niña could delay the development of La Niña in the Pacific, slowing its cooling effects across the global climate, says McPhaden. “There could be a tug of war between the Pacific trying to cool itself and the Atlantic trying to warm it.”

Meanwhile, according to CBS, "California experiences rare August snowfall in Sierra Nevada Mountains near Mammoth."