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Weather in Focus

By Chris DeWeese
Senior Editorial Writer
Good Morning. After a recent quiet spell in the Atlantic hurricane season, we’re certainly paying attention to the three areas of interest that have been identified for potential development. As meteorologist Chris Dolce wrote in Tuesday’s Brief, 88% of Atlantic hurricane season’s average activity takes place after Aug. 15, so it’s not surprising that we’re starting to see some developments on the map.

Something else Dolce said in our newsroom yesterday caught my attention: All four Category 5 continental U.S. landfalling hurricanes on record were tropical storms just three days beforehand. This fact underscores how quickly tropical storms can intensify, emphasizing how important it is to pay close attention to the tropics. (To be clear, none of the current areas we’re watching show much indication of becoming anything this serious, however.)

Weather In Focus

track of Tropical Storm Hilary.
This is the track of Tropical Storm Hilary, which formed yesterday and will strengthen into a hurricane off Mexico’s Baja Peninsula. While it will then weaken, Hilary’s remnants will likely bring locally heavy rain to parts of California, including the Los Angeles Basin, and Desert Southwest.

What We’re Tracking


A hurricane in the Eastern Pacific is renamed a cyclone or a typhoon if it crosses

  1. The International Date Line
  2. The Pacific White Line
  3. The Prime Meridian
  4. The Tropic of Cancer
See the answer at the end of this newsletter.

This Caught My Eye

Photograph of smiling meteorologist Jon Erdman wearing a button up shirt. Jonathan Erdman
Senior Digital Meteorologist
track history of Hurricane Kay.
Track history of Hurricane Kay last September.
Kay-jà vu?

“History doesn’t repeat itself, but it often rhymes.” While it’s debatable if Mark Twain ever said that, some meteorologists may be uttering that regarding the Southwest U.S. right now.

Last September, the remnant of what was once Hurricane Kay dumped locally flooding rain and whipped up strong winds in parts of Southern California and the Desert Southwest. Almost one year later, a similar scenario appears to be setting up with Tropical Storm Hilary. In Southern California and the Southwest, locally flooding rainfall, gusty winds and high surf at the beaches are expected beginning this weekend. We have more details on this forecast here.


Weather Words

two trucks seen through wavy lines of heat.
(Hoptocopter via Getty Images)
Today’s weather word comes from Norn, a mysterious Scandinavian language that was spoken in Shetland, Orkney and parts of Scotland until the 18th and 19th centuries. Stavalu refers to the quivering motion in the air caused by heat rising from a sun-warmed surface.

Interestingly, stavalu can also refer to the trembling movement of a cobweb disturbed by wind, which, if you think about it, has interesting similarities with the quivering air we see due to heat rising.


‘Recent Changes Don’t Look Natural.’ A Paleoclimate Scientist On Climate Change

a chart of average global temperatures from 1940-2023.
Average global temperatures in July 1940-2023. This year is on the far right as the highest of any year. (Data: ERA5. Credit: C3S/ECMWF)
With NOAA and NASA crunching the numbers and determining that last month was the hottest on record, a lot of people have been wondering about when the planet was last this hot. To learn more, I spoke with Dr. Darrell Kaufman, a Regents’ Professor at North Arizona University’s School of Earth and Sustainability. Here’s our conversation, edited for brevity.
How do paleoclimate scientists determine the temperatures of the past?

The primary source of information about past climates going back many thousands of years is contained in mud that accumulates at the seafloor and in depressions on land. Remains of plants and animals from the past are preserved there. They can be identified and most of them have living counterparts with known climate preferences. So we can translate the biotic assemblages into estimates of temperature and other climate variables. Besides organic remains, the sediment can contain a large variety of geochemical fingerprints of past climate.

With extreme heat gripping parts of the globe this summer, people are wondering when the last time Earth was this hot. What can the research that scientists like you have done tell us about that?

We can provide the long-term context of climate change that’s needed to put ongoing changes in perspective of what’s normal or extreme. From that perspective, recent changes don’t look natural. The Earth has entered a new climate state, one characterized by a global warming level of more than 1 degree Celsius above pre-industrial levels, and we won’t be going back any time soon. The last time Earth experienced a climate with this level of global warming was at least 100,000 years ago.

What do you think is important for people to know about looking at the climate now and comparing it to the past?

The changes that humans have set into motion by increasing the level of heat-trapping gasses in the atmosphere will play out over many centuries if not millennia. Looking at climate changes of the past shows that ice sheets and deep oceans move slowly compared with human lifetimes, but they are major controls on the climate system.


1969: Hurricane Camille Roars Ashore
a chart showing Hurricane Camille’s path.
The deadly Category 5 Hurricane Camille, the second most intense hurricane to strike the continental U.S. on record, made landfall in Mississippi on this date 54 years ago. Only the 1935 Labor Day Hurricane was stronger.

Camille brought with it a storm surge of a staggering 25 feet. One-hundred-forty-three people died from Camille’s landfall, and another 113 perished in Virginia due to flash flooding from Camille’s remnants.

A. The International Date Line
This just happened to Dora. Learn more here.

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