“Slow” Doesn’t Mean “No”
06/02/2015 07:56AM ● Published by Aimee Cormier
Hurricane season officially begins on June 1. But, it’s never too early to get prepared. This year, forecasters are expecting a “slow” hurricane season. So, what exactly does that mean?
“Slow season means the forecast is for fewer hurricanes than normal in the Atlantic basin, normal being over the last 30 to 40 years,” explains KATC’s Chief Meteorologist Rob Perillo. “But, there is no such thing as a slow hurricane season if the one and only hurricane during that season slams you. I think that’s a misnomer.”
For 2013 and 2014, the Gulf Coast had hurricane-free seasons. Early predictions are that 2015 will be relatively calm as well. According to famed forecasters Dr. Philip Klotzback and Dr. William Gray of Colorado State University’s Department of Atmospheric Science, the Atlantic basin will see fewer than the average number of storms in 2015.
On average, the Gulf Coast experiences 12 named storms, six hurricanes and three major systems each season, which is about a 30 percent chance. For this year, the Gulf Coast and East Coast both have a 15 percent chance of getting hit by a hurricane. Klotzback and Gray predict that the 2015 hurricane season will consist of seven named storms, three hurricanes and one major storm with winds about 110 mph. The HUGO (Hurricane Genesis & Outlook Project) at Coastal Carolina University projects eight named storms, four hurricanes and two major hurricanes.
Between 1950 and 2013, the historic average of hurricanes making landfall is .65 on the East Coast and .95 along the Gulf Coast. So far this year, it’s good news for the Gulf Coast. HUGO estimates that .14 hurricanes will hit the East Coast in 2015, and only .1 will make landfall on the Gulf Coast.
How accurate are these projections? In 2014, the forecast called for nine named storms with three hurricanes and one major storm. In actuality, eight named storms formed, with six becoming hurricanes and two major systems.
To be classified as a hurricane, a storm must have wind speeds of 74 mph or higher. According to the Saffir-Simpson Hurricane Wind Scale (SSHWS), updated in 2012, Category One has average wind speeds of 74-95 mph; Category Two, 96-110 mph; Category Three, 111-129 mph (Katrina and Rita, 2005); Category Four, 130-156 mph (Charley, 2004), and Category Five, 157-plus (Andrew, 1992).
Usually, forecasters expect a weak season in the Atlantic basin that has for years been dominated by El Niño. This phenomenon occurs when the Pacific Ocean is abnormally warm off the coast of Peru (El Niño). Warmer waters increase energy, which tends to increase the upper level winds over the Caribbean and Atlantic. In turn, this causes more wind shear, making it hard for storms to develop. “El Niño is warmer than normal waters along the equatorial Pacific on the eastern side, and what that does is it usually allows for more storminess in the Pacific,” Perillo explains. “As a result of that, it allows for stronger upper level winds across the southeastern Gulf and the Caribbean, which thereby increases the shear, which reduces the total number of tropical systems in the Atlantic basin.”
El Niño is not necessarily a factor for Louisiana’s storm seasons. Historic hurricanes Audrey (June 1957), Betsy (September 1965), Alisha (August 1983) and Andrew hit in El Niño years. “Interestingly enough, in years where we have El Niño, there is no signal for Louisiana upwards or downwards on the amount of activity,” Perillo observes. “I spoke to Dr. Klotzback just a few weeks ago, and he said that actually, there’s a little bit of a slight uptick in the number of storms for the Louisiana coast. Now, that doesn’t mean we are going to get hit this season because we have an El Niño and fewer than the average number of storms this year. But, any year, anything is possible. Fewer storms overall means maybe fewer landfalls and maybe less destruction. But, it only takes one well-placed hurricane at the wrong time in a big city or in your own back yard to make it a very bad season.”
With that in mind, now is the time to get prepared for hurricane season. Your basic disaster supplies kit should include a three-day supply of non-perishable food and a manual can opener; water, one gallon per person per day (for hydration and sanitation); battery-powered or hand crank radio, flashlight and extra batteries, first aid kit, local maps and cell phones with chargers. “You want to get some of the things that you should need if your power goes out,” Perillo advises. “You also want to have a backup plan for getting your information. The most important thing is knowing what’s going on. If you get cut off from radio or TV and you rely on social media, then you might not know the most current information.”
Hurricane season runs until Nov. 30. Historically, major storms occur in late July, August and September. South Louisiana’s hurricane season generally peaks on Sept. 10. This year marks the 10-year anniversary of two of the Gulf Coast’s most devastating storms in history: Hurricane Katrina, the costliest and one of the five deadliest hurricanes in the U.S., on Aug. 29, and Rita, the strongest tropic cyclone ever recorded in the Gulf of Mexico, on Sept. 24. Hurricane Andrew, the third costliest hurricane on record, hit Louisiana on Aug. 26, 1992.
Even though prognosticators predict a slow season this year, remember -- “No matter what the forecast for the season is, we say going into each and every season, be equally prepared,” Perillo cautions. “Because, we cannot tell you if there’s going to be one hurricane or 15 hurricanes, and whether one of these is going to be striking here.”