2020's hurricane season was the most active tropical season in more than 170 years with a record 30 named storms, 12 U.S. landfalls, and nearly 100 billion dollars in damage. The 2021 Atlantic Basin Hurricane Season is expected to be above average, though not quite as active as 2020. This article briefly discusses how many storms we can expect, why it will be active year, when and where the storms are likely to develop, and what states will most likely be impacted.
Tracks of the 2020 land-falling tropical systems. Louisiana was especially hard hit.
HOW MANY NAMED STORMS WILL WE HAVE DURING THE 2021 SEASON?
The National Oceanic & Atmospheric Administration just released their outlook for the 2021 hurricane season. NOAA is expecting an above average season, as is Colorado State University, The Weather Company, Accuweather, and other forecasting companies/agencies. Here's a look at NOAA's outlook that was issued May 20th:
The main takeaway from NOAA's outlook is that there is a 90% chance for an average or above-average season and only an 10% chance that this will be a below-normal season. NOAA's forecasters anticipate an above number of named storms, hurricanes, and major hurricanes.
It might be of interest to know that what is considered "average" has changed for the 2021 hurricane season. Due to advances in satellite technology and observations, NOAA and the NHC are able to identify storms that might have previously been unnamed. This graphic shows how the increase in the "average" number of storms is increasing this year.
WHY IS IT GOING TO BE AN ABOVE AVERAGE SEASON?
Did you know that the hurricane season is influenced by world-wide weather interactions? Storms in Indonesia to the jet stream over Africa can influence whether your home is impacted by a hurricane. Here are the main factors that lead Cloud Nine Weather Services and other forecasting entities to believe that this season will be above average:
Warmer than average sea surface temperatures (SST)
ENSO-neutral pattern and other supporting teleconnections such as the Atlantic Multidecadal Oscillation. La Nina just ended over the past month.
Weaker than average trade winds in the main development region (MDR)
Enhanced West African Monsoon
Comparison to analog (aka. similar) hurricane seasons with a similar setup
Warm sea surface temperatures are fuel for an active hurricane season. Here's a look at a massive ocean water heat wave that is currently occurring from Africa to the U.S. The orange shading represents warmer than average sea surface temperatures. The warmer waters can occur naturally, though anthropogenic climate change is definitely creating an oceanic warming trend. (Graphic Credit: www.marineheatwaves.org)
La Nina, cooler water in the eastern equatorial Pacific, was a big factor in 2020's active hurricane season. La Nina decreases the amount of wind shear over the Atlantic Basin providing very favorable conditions for hurricane development. El Nino, warm water in the eastern equatorial Pacific, creates a hostile environment for hurricane development in the Atlantic Ocean. Over the past month, sea water has warmed off the coast of Peru resulting in an El Nino Southern Oscillation - Neutral pattern. This means that we are not in a La Nina or El Nino pattern. This also means that there isn't adequate wind shear to rip apart most tropical waves that will develop over the Atlantic/Gulf. If La Nina does happen to return during the Fall then the number of storms in the Atlantic Basin will likely be on the higher end of NOAA's predictions.
WHEN AND WHERE DO STORMS TYPICALLY DEVELOP?
The peak of hurricane season occurs around September 10th, when the Atlantic Ocean has reached its peak temperature. Late summer and early fall is when we can expect the big boys to develop off the coast of Africa and track westward. Though, early summer and late fall can produce menacing tropical storms and lower end hurricanes that threaten Florida and the rest of the southeastern coastline.
The Gulf is the quickest to warm and and thus the first to see tropical development. Here's a look at the main development regions for every month of hurricane season:
IS ANY AREA OF THE U.S. AT GREATER RISK OF LANDFALL THIS YEAR?
During yesterday's press conference with NOAA, the agency elected to deflect a number inquiries into where in the U.S. a landfall is most likely to occur this year based on analog hurricane seasons, ENSO, AMO, & other teleconnections. This is a wise move on NOAA's part as a government entity responsible for making forecasts that result in billion dollar decisions. Admittedly, the hurricane forecasts months in advance are an imperfect science. However, there are clues that we can analyze which will help us gain insight into the areas of coastline that may be at greater risk of a landfall this season.
Accuweather's forecasters are mentioning that the Bermuda/Azores High Pressure is likely to be weaker and farther north this year (than it was in 2020). A weaker high pressure means that storms are less likely to be pushed farther west and could take a path into Florida, the eastern seaboard, or with any luck remain out to sea.
Colorado State University does a great job every year with their thorough hurricane season outlook. They have elected to issue the chance of a tropical system impact down to the state and even county level. The following graphic reflects CSU's 2021 forecast for every state with a coastline. Their forecasters are anticipating a 75 percent chance of a hurricane impacting Florida this hurricane season. During an average hurricane season, there is a 58% chance that Florida will be impacted by a hurricane. So, this year there is a 17% greater chance of a hurricane impact.
Data compiled from Colorado State's 2021 hurricane forecast showing the odds of a hurricane impact in each state compared to an average hurricane season. (Graphic created by Bryan Bennett)
CSU's outlook shows that Florida is the most likely state to be impacted by a hurricane this season. This is true, but you must also consider that Florida has 8,436 miles of coastline compared to Mississippi's 359 miles of coastline. So, of course, Florida is almost always going to have the highest chance of a hurricane impact not only because of it's semi-tropical latitude, location sticking out into the ocean, but also because of its large size. So, folks in Mississippi, for example should be just as prepared for a hurricane landfall as citizens of Florida.
Now Is The Time To Prepare
The 2021 Atlantic Basin is going to be active again this season. Though, as you have probably heard before, it only takes one. In 1992, there were only six named storms but one of those storms was Category Five Hurricane Andrew that devastated southeast Florida.
Stores are currently fully stocked with all of the supplies needed to properly be prepared for a hurricane, but as we have seen over the past year that can change very quickly. Toilet paper and gasoline became prized commodities for various reasons over the past year. If a hurricane heads toward your home you bet can bet that stores will be depleted of generators, bottled water, canned food, batteries, and other essentials. Covid-19 is still also resulting in havoc in supply chains, so important items may disappear even quicker off of store shelves.
Pay attention to guidance from the NHC and local officials on potential evacuation orders. Storm surge is a very serious threat along coastlines and connected waterways. Wind and freshwater flooding is a formidable threat inland. If at all possible, it's better to evacuate you, your family, and your pets instead of facing mother nature's wrath.
When considering your hurricane plan it is best to plan for a minimum of three days without any outside help. If a hurricane does strike, it will take time for emergency officials to be able to safely reach you. So you should have first aid kits and enough supplies to last until help can arrive.
Everyone stay safe out there this hurricane season. Lets hope for a season like we had in 2010 when there were a whopping 19 storms and 12 hurricanes, BUT only one weak tropical storm made landfall in the U.S.
If you have any questions about this season's hurricane outlook or any storm that develops this season feel free to contact Cloud Nine Weather Services at cloudninewx@gmail.com.
Comments