What Caused Above-Average 2016 Hurricane Season?

It’s the thirtieth of November and it is a day when a lot of people let out a sigh of relief- particularly those who live in low lying areas and along the coast. It is the end of the 2016 Atlantic Hurricane Season- one that has been above normal and went as predicted.  Belize didn’t experience a lot of storms, but we did get the category one Hurricane back in August. While Earl was only a category one the damage and destruction was in the millions for Belize. Today, we spoke with the newly installed acting Chief Met officer Catherine Cumberbatch. She told us what contributed to the above normal season and why you should always be prepared despite that it is the end of the Hurricane season.

Catherine Cumberbatch, Acting Chief Meteorologist

“We usually, a forecast is issued, and what the Hurricane Season would likely be. And that forecast was for above normal. I must say, Andrea, the 2016 Atlantic Basin Hurricane Season did turn out to be above normal. We had fifteen named storms and of the fifteen named storms, seven of them became hurricanes and three of them were major hurricanes; meaning they were three or category three and greater on the Saffir- Simpson Hurricane Wind Scale. The strongest system for the season, or the biggest system for the season was Hurricane Matthew and that winds of 165 miles which was a category five and had maximum central pressure that was nine hundred and thirty-four millibars. So, that is how the season looked. It was above normal as was forecasted. As you look back on our country Belize, of the fifteen named storms that formed during the season, Belize was unfortunate to be affected by one of those storms. Everyone could recall Hurricane Earl that impacted and crossed the country on August third. It was only a category one, but Earl left a trail of destruction to the agriculture and tourism industry.”

Andrea Polanco

“Is there anything that we can attribute to that “above normal” season.  I believe in the previous Hurricane Season when we spoke with Chief Met Gonguez- then- he had said that El Nino was a major contributor to that?”

Catherine Cumberbatch

“Ok. Yes, Andrea. There were three basic main factors that contributed to the above normal 2016 Hurricane Season. One was the above warmer than normal sea surface temperature. Two was (ACE)- the Accumulated Cyclone Energy which was way above normal and third factor was the same transition from the El Nino to neutral La Nina condition. Those were the three major influence on the 2016 Hurricane Season. As we all know, in the transition phase from the El Nino to neutral La Nino condition, what it does for us in this season here in the Caribbean, it caused the wind share to be much weaker and a weaker wind share in our region usually gives way to more organized condition in the region and this would usually lead to a more higher cyclone activity.”

Andrea Polanco

“The season is over- people might say I don’t have to worry again until June first – but I know normally you’d still advise to have your plans in place; so what advice would you give to the public?”

Catherine Cumberbatch

“Although, Andrea, the season is over, history teaches us that these systems can form outside of the season. A typical example of that was in January of 2016 when we had Tropical Storm Alex that formed in the North Eastern Atlantic. So, what my advice to all Belizeans is to go over your Hurricane plan and see what are your shortfalls and weaknesses, so that if the situation arises in 2017 you will be even better prepared. That is my request to all Belizeans.”

Cumberbatch said that the Met Service remains committed to providing updated weather information in a timely manner, despite not being in the Hurricane Season. In the case of any weather related emergency event, the people of Belize will be informed.

Channel 5


Early, Late, and Far-Flung: The Eclectic 2016 Atlantic Hurricane Season

By: Bob Henson and Jeff Masters

After three relatively quiet seasons, the hurricane-generating waters of the North Atlantic, Gulf of Mexico, and Caribbean returned in 2016 to the busy production schedule they’ve maintained in most years since the mid-1990s. Assisted by the switch from a record-strong El Niño to a borderline La Niña, which reduced vertical wind shear, the 2016 season ended up above the long-term average for all of the most commonly tracked indices, with the largest number of hurricanes observed since 2012, the most major hurricanes since 2011, and the Atlantic’s first Category 5 hurricane since 2007. Persistent dryness in mid-levels of the atmosphere likely kept this season from being even more active, noted Dr. Phil Klotzbach (Colorado State University, CSU) in his end-of-season recap.

Here are the numbers for 2016 through November 30, the official last day of the Atlantic season. In parentheses are the average values for the period 1981 - 2010. Below the tally, you’ll find our look at a few noteworthy aspects of this prolonged, wide-ranging season.

Tropical cyclones (including depressions):  16
Named storms:  15 (average 12.1)
Hurricanes:  7 (average 6.4)
Major hurricanes:  3 (average 2.7)
Accumulated cyclone energy (ACE), as reported by CSU:  134 units (average 108)


Figure 1. Forecasts of the expected number of Atlantic hurricanes in 2016 as issued by a variety of forecast groups shown at the bottom of the chart. The actual total number of hurricanes through November 30 was 7, which falls within the outlooks from almost every group that issued its forecast as a range rather than a single number. Forecasts in pale blue were based on statistical models, those in red on dynamical models, and those in purple on hybrid models. Image credit: Colorado State University/Barcelona Supercomputing Center/XL Catlin.

•    The Atlantic’s deadliest hurricane in more than a decade: Matthew
The main story of the 2016 Atlantic hurricane season was Hurricane Matthew, the Atlantic’s first Category 5 storm since Felix of 2007. Matthew lasted as a major hurricane for eight days from Sept. 30 to Oct. 7, and devastated Haiti as a  Category 4 storm on October 4. Matthew killed 546 in Haiti, according to the insurance broker Aon Benfield, making it the Atlantic’s deadliest hurricane in 11 years. Damage in Haiti was estimated at $1.9 billion--a staggering 21% of the impoverished nation’s GDP, and by far Haiti’s costliest hurricane on record, according to the international disaster database, EM-DAT (previous record: $400 million 1980 dollars from Hurricane Allen.) Matthew battered Cuba as a Category 4 storm, causing $2.6 billion in damage (3.2% of their GDP.) Matthew was Cuba’s second most expensive hurricane on record, behind Hurricane Georges of 1998 ($3 billion in damage in 2016 dollars.) The Bahamas suffered $600 million in damage from Matthew (6.8% of GDP), making it their third most expensive hurricane on record behind Hurricane Frances of 2004 ($1.28 billion in losses, 2016 dollars) and Hurricane Jeanne of 2004 ($700 million in damage).

Matthew grazed the coast of Florida and Georgia before making landfall in South Carolina on October 8 as a Category 1 hurricane with 75 mph winds. Matthew’s storm surge brought water levels that were the highest ever observed along portions of the coasts of Northern Florida, Georgia and North Carolina, beating records that had been set as long ago as 1928. Near record-warm ocean waters contributed to atmospheric moisture levels that were the highest on record over portions of Florida and South Carolina as Matthew moved up the coast, allowing the hurricane to dump 1-in-1000 year rains in some areas of South Carolina and North Carolina. Matthew killed 49 people in the U.S., 28 of them in North Carolina, and U.S. damage was estimated at up to $10 billion. This would make Matthew the 17th most expensive hurricane in U.S. history. Remnant moisture from Matthew also brought flooding rains and high winds to parts of the Maritime Provinces of Canada, causing tens of millions of dollars in damage.

•    A phenomenally prolonged season. On January 14, Hurricane Alex became the Atlantic’s first January hurricane since 1955. Alex maintained Category 1 strength for almost 24 hours, peaking at 85 mph winds, before weakening to a tropical storm with 65 mph winds and making landfall on January 15 on the island of Terceira in the central Azores, roughly 1000 miles west of Portugal. No major damage or casualties were reported from Alex’s landfall. Only one other time since records began in 1851 has a January tropical cyclone landfall made landfall in the Atlantic: Hurricane Alice, which moved from northeast to southwest over the islands of Saint Martin and Saba on January 2, 1954. The only other January hurricane in the Atlantic was Hurricane One on January 4, 1938. Alex’s ascension to hurricane strength was likely aided by sea surface temperatures that were up to 1°C above average for that time of year--near 22°C (72°F.)

The season’s other bookend (assuming no other tropical cyclones form by December 31) was deadly Hurricane Otto, the first hurricane known to make landfall on Thanksgiving Day (November 24 this year) as well as the Atlantic’s strongest hurricane on record so late in the calendar. After its landfall in far southern Nicaragua, Otto weakened to tropical storm strength while moving over northwest Costa Rica, where it killed 10 people. Only one other Atlantic tropical cyclone in recorded history has killed people later in the year: Tropical Storm Odette, whose floods killed eight people in the Dominican Republic after making landfall on December 6, 2003. Otto is the first named storm on record to pass directly over Costa Rica, and as it moved into the Pacific, it became the first tropical cyclone to keep its name while moving from one ocean basin to another. (Several other storms have successfully crossed basins, but previous policy was to change the name when this occurred.)
 
The only year with anything close to this prolonged a tropical cyclone season--January 12 to November 24--was 1938, whose activity extended from January 3 to November 10. Even if we discount January storms by arguing that they represent the tail ends of prior seasons, this year’s activity still ran from May 27 to November 24. That span is just one day shorter than the classic June-to-November season, and it’s only a month shorter than the infamous 2005 season, which went from June 8 to January 6.

•    Record amounts of oceanic fuel. The very strong 2015-16 El Niño, playing out on top of relentless long-term warming associated with human-produced greenhouse gases, led to record-warm sea surface temperatures across many parts of the globe, including the North Atlantic. Many of this year’s storms developed or intensified over waters that were 1°C - 2°C (1.8° - 3.6°F) above the local seasonal average. The widespread oceanic warmth most likely played a role in extending the season, as well as supporting greater intensification in locations and time frames where it otherwise might not have occurred. Several of this year’s hurricanes hit their peak strength near or north of 30°N, where especially warm waters prevailed during peak season.


Figure 6. Large swaths of the world’s oceans experienced record-warm sea surface temperatures for the year 2016 through October, including most of the Northwest Atlantic and Caribbean. Image credit: NOAA/NCEI.

•    A year littered with landfalls. From the first named storm to the last, 2016 saw an unusually large number of its tropical cyclones (13 out of 16) passing over or near land. Actual landfalls were also numerous, and their locations were remarkably diverse, including the Azores (Alex); South Carolina (Bonnie); Florida (Colin); Mexico (Danielle); Belize (Earl); Haiti, Cuba, The Bahamas, and South Carolina (Matthew); Bermuda (Nicole); and far south Nicaragua (Otto). Tropical Storm Julie jumped the gun on landfall by becoming a named storm while it was located over eastern Florida, making it the first tropical storm on record to develop within the Sunshine State. The five landfalling storms in the United States were the most since 2008, when six storms struck.

•    The intensity challenge, circa 2016. Over the last few years, forecasters and computer models have made some real headway in the devilishly difficult challenge of predicting rapid hurricane intensification, but 2016 gave us two humbling examples of how far we still have to go. As Hurricane Matthew drifted across the southern Caribbean Sea, it rocketed in strength from Category 1 to Category 5 in just 24 hours (from 80 mph sustained winds at 03Z on September 30 to 160 mph at 03Z on October 1). The official NHC forecast at the start of this day-long burst was for Matthew to take three days to top out at high-end Category 2 strength (105 mph). Less dramatic but still eye-opening was Nicole’s surge from Category 1 to Category 4 strength in the Northwest Atlantic over just 21 hours (from 90 mph sustained winds at 06Z on October 12 to 135 mph at 03Z on October 13). Like Matthew, Nicole had also been predicted at the start of its rapid strengthening to remain just below the major hurricane threshold (Category 3). NHC often reminds users in their discussions and statements that a particular hurricane could strengthen more rapidly than indicated in the official forecast.

•    Warning woes on the East Coast. The year’s two most significant East Coast hurricane threats, Matthew and Hermine, proved to be unusually challenging from the warning perspective. Nearly the entire East Coast from Florida to Massachusetts ended up in a hurricane or tropical storm warning as a result of the two storms. Matthew’s concave coastal track cut down on the amount of wind damage, especially in Florida, while Hermine lingered just far enough off the mid-Atlantic so that many coastal stretches from Delaware to New York that had been largely abandoned for the Labor Day weekend ended up with oddly picture-perfect weather in the midst of tropical storm warnings. In both cases, the high-end risks painted by computer forecast models were enough to justify alerting residents. Strong winds, high surf, rip tides, and coastal erosion hammered the mid-Atlantic and Northeast coast during Hermine’s leisurely decay, and Matthew’s record storm surge along the Southeast coast and its catastrophic rains inland will not soon be forgotten.

•    Florida’s hurricane “drought” is over--but another record string continues. Florida got its first hurricane landfall in nearly 11 years (3966 days) with the arrival of Category 1 Hermine, which struck the state’s northeast Gulf Coast on September 2. The landfall ended a string of good fortune unprecedented in Florida records. Hermine was also the first hurricane observed in the Gulf of Mexico since Ingrid in 2013, curtailing the Gulf’s longest hurricane-free stretch on record. Hurricane Matthew’s track just off the Southeast coast until its South Carolina landfall kept it from ending yet another remarkable “drought”: the longest period between major hurricane landfalls (Category 3 or stronger) in U.S. hurricane data going back to 1851. This ongoing stretch began after Hurricane Wilma struck Florida in October 2005. A number of observers, including Robert Hart (Florida State University) and colleagues, have noted that this record is somewhat arbitrary, especially since two large landfalling systems with lesser winds but major storm surge were the nation’s second and third most costly hurricanes on record: Sandy in 2012 and Ike in 2008, respectively. In October, Capital Weather Gang’s Jason Samenow declared the U.S. major-hurricane drought to be the “most overblown statistic in meteorology.”

Still, it’s undeniably impressive that all 29 major hurricanes recorded in the Atlantic from 2006 through 2016 managed to avoid bringing Category 3 winds to the shores of the United States. Even if this is nothing more than a fluky natural variation, the major-hurricane drought reminds us that it’s been a long time since we’ve seen what truly devastating hurricane winds can do to the nation’s Gulf and Atlantic coasts.