A scientific look at hurricane prediction

 From:

The Conversation, as quoted in Scientific American

The 2024 Atlantic hurricane season starts on June 1, and forecasters are predicting an exceptionally active season.

Forecasters and climatologists look for two main clues when assessing the risks from upcoming Atlantic hurricane seasons: a warm tropical Atlantic Ocean and a cool tropical eastern Pacific Ocean.

Warm ocean surface water – about 79 degrees Fahrenheit (26 degrees Celsius) and above – provides increasing heat energy, or latent heat, that is released through evaporation. That latent heat triggers an upward motion, helping form clusters of storm clouds and the rotating circulation that can bring these storm together to form rainbands around a vortex.

The North Atlantic sea surface temperature has been shattering heat records for most of the past year, so temperatures are starting out high already and are expected to remain high during the summer. Globally, ocean temperatures have been rising as the planet warms.

HOW THE PACIFIC CAN INTERFERE WITH ATLANTIC STORMS

It might seem odd to look to the Pacific for clues about Atlantic hurricanes, but Pacific Ocean temperatures also play an important role in the winds that can affect hurricanes.

Like the Atlantic, water temperatures in the eastern Pacific oscillate between warm and cold phases, but on shorter time spans. Scientists call this the El Niño Southern Oscillation, or ENSO. The warm phases are known as El Niño; cold phases are called La Niña.

La Niña promotes the upward motion of air over the Atlantic, which fuels deeper rain clouds and more intense rainfall.

La Niña’s effects also weaken the trade winds, reducing vertical wind shear. Vertical wind shear, a difference in wind strength and direction between the upper atmosphere and the atmosphere near Earth’s surface, makes it harder for hurricanes to form and can pull apart a storm’s vortex.

In contrast, El Niño promotes stronger trade winds, increasing wind shear. It also centers the upward motion and rainfall in the Pacific, triggering a downward motion that promotes fair weather over the Atlantic.

El Niño was strong during the winter of 2023-24, but it was expected to dissipate by June, meaning less wind shear  to keep hurricanes in check. La Niña conditions are likely by late summer.

In honor of the hurricane survivors of my family

Sept 8-9, 1900.  Galveston, Texas.  Hurricane.

I'll share the life of one of my great-great aunts who raised my great grandmother.

Elizabeth Pulsifer Granger Sweet was born in Newburyport, Massachusetts in 1833.  She was the sister of my great-great grandmother Mary Granger Phillips who died just as the Civil War broke out.

Elizabeth was called Lizzy in Mary's letters from Beaumont, Texas to her, telling of her children's births, and various domestic interests, while Lizzy was living in Galveston, Texas.  I think she also raised Mary's daughters, Zulie and Ada Phillips, after she married Sidney Sweet, from New York.  They had 2 children and by the time the oldest was around 10, Elizabeth (Lizzy) was widowed (1875.)

Elizabeth Sweet (age 69) was living at 1709 Winnie St. in Galveston, as of the June 7, 1900 census, with her son Chauncey Sweet, (age 37) his wife Ada Phillips Sweet, (age 34), nephew Lucian Chamberlain, (3) nieces Ada Swasey (14) and Stella Swasey (12).
(NOTE: Ada Phillips Sweet will be honored on her birthday Sept. 15 here on my blog.)

Sept. 8-9, 1900 was the worst storm to hit that island within recorded history.  This was before storms were given names, but it was known by my grandmother, Ada Swasey Rogers and her family as the Storm of 1900.   And they would say, "Nineteen Ought."

There's a book that I was given by my grandmother about the storm, about some of the people and about the buildings, A Weekend in September by John Edward Weems (1957.)  What is interesting is the difference from today's vacation town and the city of Galveston that was then a boom town, that had become a major port connecting the western US by rail and shipping with the East.

So when a storm killed 6000 people (estimated, there were 4200 listed names) and the rail was knocked out by the storm, the survivors had to deal with the same lack of food, transportation, sanitation, and clean water that all storm survivors deal with, as well as disposal of the bodies of the dead on an island.  Horses and wagons were the standard mode of travel following the storm. The book isn't particularly enjoyable reading, and I had to steel my guts to approach it, and read it through as fast as I could.

My father's parent's families all lived through the storm.  I never heard them say a word about it.  When I asked my grandmother, she just gave me the book.  She married 5 years after the storm, so was a teen during it...(she's listed as Ada Swasey (14) in the 1900 census).  All these people that survived such an event probably had great respect for survivors of other major storms.  But they had already faced their own fears, hadn't they?

I'm sharing today's story with others on Sepia Saturday this week.  Come over there to see many other interesting photos which are sepia (or not.)