❝ The formation of a distinct pattern of sea surface temperatures in the middle of the North Pacific Ocean can predict an increased chance of summer heat waves in the eastern half of the U.S. up to 50 days in advance.
The pattern is a contrast of warmer-than-average water coming up against cooler-than-average seas. When it appears, the odds that extreme heat will strike during a particular week — or even on a particular day — can more than triple, depending on how well-formed the pattern is.
❝ The findings were published in…Nature Geoscience. The lead author is scientist Karen McKinnon of the National Center for Atmospheric Research…
“Summertime heat waves are among the deadliest weather events, and can have big effects on farming, energy use and other critical aspects of society,” said McKinnon. “If we can give city planners and farmers a heads-up that extreme heat is on the way, we might be able to avoid some of the worst consequences…”
❝ For the study, the scientists divided the country into regions that tend to experience extreme heat at the same time. They then focused on the largest of the resulting blocks: a swath that stretches across much of the Midwest and up the East Coast, encompassing important agricultural areas and heavily populated cities.
The researchers looked for a relationship between global sea surface temperature anomalies — waters warmer or cooler than average — and extreme heat in the eastern half of the U.S.
A pattern popped out in the middle of the Pacific, above a point roughly 20 degrees north latitude. The scientists could find the particular configuration of ocean water temperatures, which they named the Pacific Extreme Pattern, not only when the eastern U.S. was already hot, but also in advance of that heat.
RTFA for beaucoup details of the study. I’m looking forward to someone writing a broader relation of the whole process. Fascinating stuff.
Eideard 
“Part of the Pacific Ocean Is Not Warming as Expected. Why?” (Columbia University 6/24/19) https://blogs.ei.columbia.edu/2019/06/24/pacific-ocean-cold-tongue/
“Climate models of global warming — computerized simulations of what various parts of the earth are expected to do in reaction to rising greenhouse gases — say that the equatorial cold tongue, along with other regions, should have started warming decades ago, and should still be warming now. But the cold tongue has remained stubbornly cold.
This troubles many scientists, because the cold tongue plays a key role in global climate. For example, it affects the El Niño-Southern Oscillation, a natural cyclic strengthening and weakening of the trade winds that causes cooling and warming of the eastern Pacific surface every two to seven years. ENSO is the world’s master weather maker; depending on which part of the cycle it is in, its echoes in the atmosphere may bring heavy rains or drought across much of the Americas, east Asia and east Africa. Whether the cold tongue warms will likely affect weather across huge regions. Resulting shifts could affect world food supplies and outbreaks of dangerous weather. But our predictions of those shifts rest on climate models.”