The Claim: Hurricane Katrina, Gustav, Isaac, and Harvey dates are all August 29
Hurricane Katrina struck Louisiana as a Category 3 storm on August 29, 2005, soon to become the deadliest hurricane of the 21st century.
Exactly sixteen years later to the day, Hurricane Ida, a Category 4 storm with winds of 150 mph, made landfall in the state – and a viral claim says it’s not the only time the August 29 caused a disaster.
Shared by thousands of users on multiple Facebook posts, the claim lists the dates of historic Gulf Coast hurricanes Katrina, Gustav, Isaac and Harvey as of August 29 in 2005, 2008, 2012 and 2017, respectively.
Other articles mention Ida next to the date he made his first landing in the United States on Sunday, August 29.
But is August 29 the equivalent of Friday the 13th on the Gulf Coast? Not exactly.
All the hurricanes listed were active on 29th August, but August 29th does not mark the same event for everyone. Some made landfall in the United States around that date, but others were still offshore.
Major hurricanes are statistically more likely to occur in late August, September and early October due to favorable weather conditions including low wind shear, high atmospheric humidity, and warmer ocean and air temperatures.
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USA TODAY has contacted several users who shared the request for comment.
Hurricanes Gustav and Harvey did not hit on August 29
Users posting the meme suggest a parallel between the four historical storms and Hurricane Ida.
But only two of the historic storms listed in the meme, Katrina and Isaac, made landfall in the United States on August 29. Unlike Ida, none of the hurricanes listed in the article first hit the United States on August 29.
According to the National Hurricane Center post-storm report, Hurricane Katrina passed over southern Florida as a Category 1 storm on August 25, 2005. It then gained force over the Gulf of Mexico and struck Louisiana and Mississippi as Category 3 on the 29th. The storm caused extensive damage in a short time, losing its winds to hurricane speed late at night.
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Hurricane Isaac hit Louisiana on August 29, 2008, like Ida. However, it was also not his first landing in the United States. The tropical storm hit the southeast coast of Louisiana with winds of 80 mph on August 28, then returned to gulf waters before making a second landfall in Louisiana on August 29, according to the National Hurricane Center. .
Hurricane Gustav formed on August 25, 2008, but did not hit the United States until September 1, when it landed in Louisiana as a Category 2 storm. It made landfall for the first time. once in Haiti on August 26, where it caused severe damage and killed dozens of people as it passed over Cuba, then moved to the Gulf Coast, according to National Hurricane Center records.
Finally, Hurricane Harvey struck south Texas with a Category 4 force on August 25, 2017, rather than four days later. By the time Harvey finally made landfall for the second time in Louisiana on August 30, it had weakened into a tropical storm, reports the National Hurricane Center.
Harvey devastated coastal communities in Texas and took Katrina’s place as the costliest storm to ever hit the mainland, USA TODAY reported in 2017.
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While not all of these storms made landfall on August 29 of their respective years, it is clear that the end of August is a dangerous time for hurricane activity on the Gulf Coast. At least nine major hurricanes hit the U.S. coast during the last week of August, reported KALB, a Louisiana CBS affiliate.
However, the statistical peak day of the hurricane season for the entire Atlantic Basin is a bit later. Tropical cyclones will likely be active on September 10, according to the National Oceanic and Atmospheric Administration.
The end of August is hurricane season
The fact that Katrina and Isaac both hit Louisiana on August 29 may be enough to evoke superstition for some, but there is a scientific explanation for why so many of the most devastating tropical storms occur this time of year. .
Statistically, the most dangerous hurricanes are more likely to strike between mid-August and mid-October.
“A whopping 96 percent of major hurricane days – Categories 3, 4 and 5” occur in those eight weeks, NOAA says on its website.
The reason is related to the temperature, wind and humidity conditions at that time.
According to NOAA, most hurricanes originate from tropical waves that regularly roll off the coast of Africa throughout the hurricane season, from June 1 to November 30.
Many of these waves dissipate under the effect of wind shear, which “tears up the disturbances before they can begin”. But wind shear is at a minimum for this season’s stretches.
Additionally, the period between mid-August and mid-October sees warmer air temperatures, more atmospheric humidity, and the highest ocean temperatures in the deep tropics, where hurricanes form.
Combined, these conditions create what you might call the perfect storm for major hurricane formation.
Our note: Missing context
Based on our research, we are evaluating MISSING CONTEXT for the claim that the dates for Hurricanes Katrina, Gustav, Isaac, and Harvey are all August 29. The post doesn’t spell out the significance of August 29, but it does suggest a key event lined up for all hurricanes on that date. Hurricanes Katrina and Isaac both made landfall in Louisiana on August 29, but first hit the United States on earlier dates. In contrast, Hurricanes Gustav and Harvey were both offshore on August 29.
Our sources of fact-checking:
- USA TODAY, August 29, damage report: Hours after landing Ida remains a powerful Category 3 storm ‘
- National Ocean Service, accessed August 28 What is the difference between a hurricane and a typhoon?
- National Hurricane Center, September 14, 2011, Tropical Cyclone Report: Hurricane Katrina
- National Hurricane Center, September 19, 2014, Tropical Cyclone Report: Hurricane Gustav
- National Hurricane Center, January 28, 2013, Tropical Cyclone Report: Hurricane Isaac
- National Hurricane Center, May 9, 2018, Tropical Cyclone Report: Hurricane Harvey
- National Oceanic and Atmospheric Administration, August 22, 2016, The peak of hurricane season – why now?
- National Oceanic and Atmospheric Administration, accessed August 30, Hurricane Climatology
- KALB, August 25, 2020, Why are there so many tropical cyclones at the end of August?
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