Share |

Better Hurricane Forecasting and Preparedness Mean Fewer Deaths

Patrick J. Michaels

What seemed impossible decades ago is now true: When they make
landfall, big hurricanes aren’t killing many people. Only truly
exceptional storms — or more likely exceptionally poor
preparedness — spawn large numbers of fatalities in the
United States when one comes ashore. The big death tolls are now
from flooding, often days later.

Of the top 30 killer hurricanes that have struck the U.S.
mainland since 1850, only three (Floyd in 1999, Katrina in 2005, and Harvey in 2017) were in
the past four decades. Half of the top 10 killer storms occurred
before the widespread adoption of radio.

The lesson? Surviving a landfalling hurricane is becoming
easier, thanks to communication, better forecasting and
preparation.

Ten years ago, Category 5 Hurricane Dean slammed into Mexico’s
Riviera Maya and killed no one. The lowest barometric pressure at
landfall was 26.72 inches. If it had hit the United States, Dean
would have barometrically ranked third on the all-time monster
list, behind the 1935 Labor Day hurricane in the Florida Keys, and
1969 Hurricane Camille on the Mississippi coast.

A half-century before Dean, Category 5 Hurricane Janet hit in
the same spot, had a similar central pressure, and killed an
estimated 500 people. So what changed?

Preparation was the key. Dean was a well-behaved and
well-forecast storm, and the Mexican government embarked upon a
massive evacuation of vulnerable cities, towns and 80,000 tourists.
Undoubtedly, this saved a large number of people, as some of the
coastal towns were virtually wiped out. The government of Mexico
was rightfully proud of its remarkable achievement.

Irma’s death toll currently stands at 75, tragic but remarkably
low considering the tremendous reach of its damaging wind field,
all the way from Key West to Atlanta, affecting more than 20
million people. At landfall, when the storm’s center first crossed
the coast, there were nine fatalities in the Keys, but half appear
to have been from natural causes.

Apparently, there were only two deaths when Category 4 Harvey
slammed into Rockport and Corpus Christi, Texas. Subsequent inland
flooding, associated with about 80 fatalities, could just as easily
have occurred with a mere tropical storm. For example, in 1979
Tropical Storm Claudette drenched Alvin, Texas, also near Houston,
with 43 inches of rain in 24 hours, still the national daily
rainfall record.

Which goes to show that prediction makes all the difference.
Even with adequate communication, a bad forecast is deadly. An
abominable one resulted in about 700 fatalities (United States and
Canada) in the 1938 Great New England Hurricane. The 1935 Labor Day
hurricane pretty much came out of nowhere, and more than 400 people
died in the Florida Keys.

A bad forecast and bad communication is the worst-case scenario.
In 1900 in Galveston, Texas, an estimated 8,000 to 12,000 people
perished in a Category 4 storm not dissimilar to Harvey at
landfall. When warned by Cuban forecasters that a huge hurricane
was on track between there and the Gulf Coast, Washington’s Weather
Bureau brushed them off with an imperialist flick. By the time the
Galveston forecast office issued a hurricane warming, the island
was already overwashed.

Since the 1950s, forecasts have improved incrementally, and
mega-killers have become rare. Hurricane Audrey in 1957, a top-30
killer, unexpectedly pummeled Lake Charles, La., and led to an
increased research effort that greatly improved forecasts.

Since then, the distance between where a hurricane is forecast
to be and where it winds up has been reduced to about 200 miles for
four and five days in advance. Official three-day forecasts didn’t
even become operational until 1964, and five-day forecasts began in
2001. The combination of improved forecasts and mass communication
has been enhanced by the internet and 24-hour news and weather
channels that clamor for your attention by maximizing plausible
threats.

Storms with substantial mortality are now true freaks, or their
effects are enhanced by old-fashioned human bungling.

The 2005 Hurricane Katrina had elements of both. It was well
forecast, but that didn’t matter. While it was technically a
Category 3 storm at landfall, it was huge in extent and piled up
tremendous amounts of water in its northeastern quadrant,
unleashing it on the Mississippi and Alabama coasts. In both
places, the storm surge reached the U.S. record of 27.8 feet high,
and water surged a remarkable six miles inland. Altogether, 238
people died in Mississippi. Under any circumstance, Katrina was
going to be a big killer there.

But New Orleans was where human bungling came in. In 1965,
Category 3 Hurricane Betsy struck New Orleans, killing nearly 60
people in floods. Levees that were supposed to hold back a
wind-whipped Lake Ponchartrain and the Mississippi River failed. In
response, the U.S. Army Corps of Engineers promised a new levee
system that would withstand such a storm.

The new levees failed utterly in Katrina. Congress didn’t
appropriate enough money, and the Corps drilled pilings supporting
the flood walls to only half the planned depth to ensure stability. As a
result, about 1,000 residents (the true number will never be known)
perished in a storm in which the local airport never even recorded
a hurricane-force wind.

Floods, human-assisted or otherwise, that can occur days after a
storm hits, are now the killers. Absent an extreme storm or poor
planning or infrastructure, we are now to the point where
hurricanes that previously killed hundreds or thousands as they
came ashore now produce few fatalities, testimony to our abilities
to increasingly adapt to these terrible storms with better
communication and better science.

Patrick J.
Michaels
is the director of the Center for the Study of Science
at the Cato Institute.