But this isn't the whole story.

The big picture: The ongoing heat wave is part of a longer-term accelerated warming trend that is altering life for Alaskans, many of whom live in rural communities dependent on ice and snow cover for transportation and hunting.

By the numbers: The most recent heat has been staggering, but so too is the long-term picture. Alaska has now had its:

• Warmest 12-month period on record, (July 2018 through June 2019) since 1925.
• Warmest 24-month period (July 2017 to June 2019)
• Warmest 48-month period (July 2015 to June 2019)
• Warmest 64-month period (July 2015 to June 2019)

What they're saying: The duration of the heat, plus the shockingly rapid and early disappearance of sea ice from the Bering and Chukchi Seas is most notable, Rick Thoman, a climate expert at the University of Alaska, tells Axios.

Meteorologist Brian Brettschneider said the record heat would most likely not have happened without the overall, climate change-driven warming of the state.

"Weather happens on top of climate. An airmass similar to what we just experienced has occurred several times in the past. What's different now is that the very warm airmass was placed over an environment that has already warmed by several degrees," he told Axios.

Go deeper: Heat wave brings record-breaking temperature highs to Anchorage

Why it matters: Scientists hope a better understanding of how zebrafish sleep, down to the cellular level, could unlock avenues for new treatments of sleep disorders that affect 50-70 million Americans but are often undiagnosed. It could also improve their understanding of sleep's role in memory and our physical health.

What they did: Zebrafish lack a neocortex — the part of the mammalian brain involved in higher order functions such as sleep and the target of sleep studies — so the scientists from Stanford University and institutions in Japan and France needed to find a workaround.

• They developed an imaging platform that allowed them to view proxies for brain and muscle activity via fluorescence, as well as heart rate and eye movement.
• They used two-week-old zebrafish since they are transparent, and therefore ideal for fluorescent imaging techniques.
• They also performed other experiments to determine the effects of particular compounds on zebrafish sleep and wake cycles.

What they found: Ependymal cells — present in humans and zebrafish, and known to play a role in the brain and spinal cord — are among the first to be activated as the fish fall asleep.

• The researchers also found human hypnotics — compounds found in sleeping pills and anesthetics — can also induce sleep phases in the fish that are analogous to humans.
• And similar to what is seen in humans, chemicals released by neurons in the zebrafish brain regulate the creature's muscles and sleep.

What's new: Scientists had observed invertebrates (octopi, insects) and vertebrates (fishes, amphibians, birds, mammals) sleeping but the physiological signatures of sleep, like rapid eye movements, had only been observed in mammals, birds and reptiles, study co-author Philippe Mourrain of Stanford University tells Axios.

What they're saying: “You can’t just say sleep is sleep,” Jerry Siegel, a sleep scientist at UCLA who was not involved in the study, told National Geographic. He cautioned that connections between sleep in young zebrafish and sleep in humans are less straightforward than the study suggests. For example, he said, many mammals lack REM sleep completely, and some mammals sleep 20 hours a day whereas others just need 6 to 8 hours or less.

The study's lead author, Louis C. Leung of Stanford, tells Axios:

"I encourage everyone to cherish what has taken 100's of millions of years to create and hope there is soon a change in the public narrative regarding the importance of sleep — we should be proud not embarrassed to get enough sleep."

What's next: Developing animal models that examine sleep functions at the cellular level, like the one in this study, could lead to treatments for sleep disturbances that are linked to psychiatric disorders as well as Parkinson's and Alzheimer's.

Go deeper: Americans are sleeping more

How it works: The National Hurricane Center is predicting that Barry will become a tropical storm by Friday, and intensify into a Category 1 hurricane by Saturday, before making landfall along the coast of Louisiana.

• The storm's winds are not the main threat, however.
• Up to 2 feet of rain is likely to fall in parts of Louisiana as the storm wanders onshore like a car inching forward at rush hour. This rain could overwhelm New Orleans' pumping systems, causing a repeat of Wednesday morning's flash flood emergency.
• The rain, combined with a storm surge of 3–5 feet from the incoming storm, could cause the Mississippi River to rise to near or above 20 feet in New Orleans.
• The river levees protecting the city are 20 feet high, and haven't been tested in this way. (Hurricane Katrina in 2005 caused failures in the city's storm surge protection system.)

Between the lines: The National Weather Service has issued a rare "High Risk" excessive rainfall outlook for coastal Louisiana, including New Orleans, three days in advance. Since this product became available in 2007, such day 3 outlooks have only been issued twice.

• One such instance was for Hurricane Florence, which caused billions in flood damage in North Carolina in 2018, and the other was Hurricane Harvey, which unleashed the heaviest rainfall event the U.S. has ever experienced.

Why now? Ordinarily, a storm of this magnitude would not risk overtopping New Orleans' levee system.

• However, the massive amount of rain that has fallen across the Plains, Midwest and Mississippi River Valley has created an exceptional antecedent condition that sets up a potentially unprecedented disaster.
• The Mississippi River at Baton Rouge has been at flood stage since late February, an unprecedented stretch.

Climate change may be playing some role in this as well. While a tropical storm or hurricane in the Gulf of Mexico during mid-July is relatively common, scientific studies show that as air and ocean temperatures increase, more rain is falling in heavy bursts, including from tropical cyclones.

• Modeling studies show that future tropical cyclones will carry even more water vapor with them, and bring more flooding to the areas they hit. They may also have stronger winds, overall, than typical storms today.
• Other research suggests that tropical storms and hurricanes are, in general, slowing their forward movement as the climate changes, which also favors major floods.
• In addition, studies show that climate change can set in motion a series of unprecedented events, similar to a domino effect.
• A study published in 2018, for example, projected greater instances of simultaneous extreme events with wide-ranging repercussions as global warming continues during the next several decades.

The bottom line: Residents of New Orleans, and indeed much of the central Gulf Coast, need to prepare now for a significant, dangerous storm.