Isaac’s Storm: Galveston Hurricane

Erik Larson “Isaac’s Storm: Galveston Hurricane” Random House, 1999, 277 pp.

I continue to read books by this author.  In the current instance, author Larson provides a history of the Galveston Hurricane of September 8, 1900 that virtually destroyed the entire city and killed at least 4,263 people.  This hurricane still holds the record as the most lethal hurricane to hit the US in terms of casualties. 

The author chronicles the hour-by-hour progress of the hurricane and its 15 foot storm surge and winds with gusts as much as 200 miles an hour and a barometric low pressure of 28.48. 

The Isaac of the title is Isaac Cline, who had been sent to Galveston in 1891 to head up the Texas Section of the U.S. Signal Corp's Weather Service, and much of the story is told through Isaac’s eyes. The story vividly documents the poor state of meteorology at the turn of the century and the resulting no-warning to Galveston.  Much of what was passed off as science regarding the weather was really just speculation.  The Weather Service in Washington was under the iron thumb of director Willis Moore who did not like to give out bad news.

After leaving Galveston in a shambles, the storm went on to bring rain and hurricane-force winds as far north as Chicago before finally sputtering out. Cline, who lost his wife in the hurricane, ultimately became one of the foremost hurricane experts in the country. Moore was fired for using his office to further his political career. And Galveston reinvented itself; this time on fill that raised portions of the city as much as 22 feet above their pre-storm levels. The city also constructed a 17-foot-high seawall above the beach which stands behind an advance barrier of granite boulders twenty-seven feet in width.  

My Notes:

Pg. 88:  Under ordinary circumstances, the process of rain production depletes clouds.  The ‘sink rate,’ or the rate at which water leaves a cloud, exceeds the supply of moisture arriving from the air and sea below, causing clouds to dissipate.  But hurricanes defeat this cycle.  They use wind to harvest moisture and deliver it to their centers.  As the wind races along the surface of the sea, it increases the rate of evaporation and captures spindrift and foam.  The faster the wind blows, the more vapor it picks up and the more energy it transfers to the storm.  The resulting surge of condensation and heat in the storm’s core causes even greater volumes of air to rush into the sky.  Pressure falls again.  Wind velocities increase.  The cycle repeats itself.  The result can be a rainfall more akin to the flow from a faucet than from a cloud.

In 1979 a tropical storm named Claudette blew off the Gulf near Galveston and deluged the town of Alvin, Texas, with forty-two inches of rain in twenty-four hours, still the US record for sheer intensity.  (The world record in 73 inches in twenty-four hours in the Philippines.  Total accumulation have been higher: Ninety-six and a half inches of rain once fell on Silver Hill, Jamaica, over four days.  That’s eight feet.  Hurricane Camille, which came ashore on the Gulf Coast in August 1969, was still flush with water two days later when it reached Virginia. It jettisoned thirty inches of rain in six hours.

Pg. 121:  Normal pressure at sea level is 29.92 inches, or 14.7 pounds per square inch.  In the wall of a hurricane eye, spiraling and ascending winds lift air at over a million tons per second.  AS the air soars, pressure at the surface falls.  Air within the eyewall rises with so much force it literally lifts the surface of the sea, on foot for each one inch of barometric decline.  The lowest barometric reading ever recorded was 26.22 inches, during Hurricane Gilbert in 1988.  Gilbert raised the level of the sea by over three feet.

Pg. 124:  Waves form by absorbing energy from the wind.  The longer the ‘fetch,’ or the expanse of sea over which the wind is unobstructed, the taller a wave gets, the more efficiently it absorbs additional energy.  Generally, its maximum height will equal half the speed of the wind.  Thus a wind of 150 miles an hour can produce waves up to 75 feet tall.  Other conditions, such as the chance superimposition of two or more waves, can cause waves to grow even bigger.  The tallest wave on record was 112 feet, but occurred amid steady winds of only 75 miles an hour.

Pg. 193:  The Galveston storm’s track intersected the coastline at a ninety-degree angle, with the eye passing about forty miles west of the city.  This was the worst possible angle of approach, for it brought the hurricane’s most powerful right flank directly into the city.