Hurricane Alley
Atmosphere Daily Earth Science

Hurricane Alley: A flood of storms in 2020

The hurricane outlook over the next several months indicates a busy storm season. NOAA’s August 6 update predicts twice the usual number of named storms moving through Hurricane Alley by November 30 (end of hurricane season). Hurricane Alley is a belt of warm ocean water stretching from North Africa to Central America.  An average hurricane season produces 12 named storms in Hurricane Alley, six of which become hurricanes. Typically, half of those hurricanes rise to Category 3 or above. The current prediction is for up to 25 named storms with 11 hurricanes, six becoming Category 3 or above. We are already on our ninth named storm, an event usually occurring around October 4.

The most active hurricane season on record was 2005, when 28 named cyclones produced 15 hurricanes. It was August 2005 when hurricane Katrina charged northward across the Gulf of Mexico, bringing a 25-foot storm surge. At landfall on August 29, a mountain of water collided with the Louisiana coast, overwhelming New Orleans’ flood defenses and submerging the city. Katrina became the costliest tropical cyclone on record, leaving over 1800 people dead and a final damage bill of $168 billion (inflation-adjusted).

Conditions are ripe for disaster

Hurricanes feed off of heat, so warm ocean water is a critical enabler for hurricane development. As winds sweep across the ocean’s surface, they suck up heat energy and moisture from the warm waters. This hot, water-saturated air ascends due to buoyancy, and winds then converge on the low-pressure zone created by the rising air, and a tropical storm is born.

This year, warmer than average seas extend across the Atlantic and into the Caribbean. Ocean waters along the U.S. Atlantic coast and in the Gulf of Mexico are also warmer. The entire length of Hurricane Alley is radiating more heat than usual, and this heat puts the cyclone machine into high gear, raising the risk of increased coastal storm damage in 2020.

But there is a second contributing factor to predicting a doubling of storm activity. Across the Americas and out in the Pacific Ocean’s tropical waters, a La Niña event is developing. Cooler-than-average water temperatures associated with this event have the long-reaching effect of weakening wind shear high above Hurricane Alley. High wind shear discourages the development of tropical storms by disaggregating the upper atmosphere conditions needed for the storm to strengthen. However, low wind shear encourages the development of more tropical storms.

NOAA’s report is just a prediction for now. We need to watch as the season unfolds to see what hurricane Alley throws at coastal America.


ArcheanWeb:

Hurricanes more dangerous than in the past (Source: ArcheanWeb) – https://archeanweb.com/2020/06/01/hurricanes-more-dangerous-than-in-the-past/  Also:

Flooding and climate change: Death by storm surge (Source: ArcheanWeb) – https://archeanweb.com/2020/08/03/flooding-and-climate-change-death-by-storm-surge/  Also:


Sources:

‘Extremely active’ hurricane season possible for Atlantic Basin (Source: NOAA) – https://www.noaa.gov/media-release/extremely-active-hurricane-season-possible-for-atlantic-basin  Also:

Feature Image: Hurricane Alley (Modified) – By NASA GSFC – Public Domain http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=16296 https://earthobservatory.nasa.gov/images/3780/sea-surface-temperatures-in-hurricane-alley, , https://commons.wikimedia.org/w/index.php?curid=16677137

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.