Terugblik atlantic hurricane season 2017

Door Dr. Jeff Masters & Bob Henson


The strongest hurricane of 2017, Hurricane Irma, bears down on the Leeward Islands on September 5, 2017. At the time, Irma was at peak strength--a Category 5 storm with 185 mph winds. Bron afbeelding: NASA & Wunderground.com

The Atlantic hurricane season, which officially runs from June 1 to November 30, has finally drawn to a close. The brutal 2017 season was an awful reminder of the huge hurricane vulnerability problem we face, and how unprepared we are for a potential future where the strongest storms get stronger and push their storm surges inland on top of steadily rising sea levels. Much of the Caribbean lies in ruins after the terrific beatings administered by the twin demon Category 5 hurricanes of 2017, Irma and Maria, and a monumental clean-up continues in Texas and Florida from two strikes by Category 4 hurricanes, Harvey and Irma. And though final estimates are not yet completed, 2017 is certain to rank as one of the top three most destructive Atlantic hurricane seasons ever, thanks to three of the top ten most damaging hurricanes ever seen—Harvey, Irma, and Maria. One preliminary damage assessment puts the U.S. damage from these three storms at $207 billion, with another $25 billion in non-U.S. damage. We are lucky the damages weren’t $50 - $100 billion higher; had Hurricane Irma tracked just 20 miles farther to north, missing Cuba, I’m convinced it would have been a catastrophic Category 5 storm in South Florida.


Preliminary track map for the 2017 Atlantic hurricane season. Bron afbeelding: Wunderground.com

The three great hurricanes of 2017 also killed large numbers of people. The preliminary death toll from Harvey is 84, and is 95 from Irma. Hurricane Maria, though, may be responsible for over a thousand deaths. New research that has not yet gone through peer-review puts the indirect death toll from Maria in Puerto Rico at 1,085 and rising, according to a story published Wednesday at vox.com. This does not include indirect deaths in the U.S. Virgin Islands, which were hit even harder than Puerto Rico. As we discussed in detail last week, the greatest number of indirect deaths on record for a hurricane is 500, for Hurricane Katrina of 2005. The official death toll in Puerto Rico from Maria is 58, with at least 26 of these being direct deaths (due to drowning or wind-related effects). The hurricane is also being blamed for over 40 other direct deaths along its path, including 31 in Dominica.


GOES-16 visible image of Maria approaching Dominica just before sunset, at 5:17 pm EDT September 18, 2017. At the time, Maria was a rapidly intensifying Category 3 hurricane, with top winds of 130 mph. Less than six hours later, it struck Dominica as a 160-mph Category 5 storm. Bron afbeelding: NOAA/RAMMB.& Wundeground.com

Twenty-three landfalls by the Atlantic storms of 2017
 

The 2017 hurricane season was exceptional for having three major hurricanes that all hit land at peak strength: Category 4 Harvey (Texas, with 130 mph winds); Category 5 Irma (Barbuda, Sint Martin and the British Virgin Islands, with 185 mph winds); and Category 5 Hurricane Maria (Dominica, with 160 mph winds.) At least 23 separate landfalls by named Atlantic storms occurred in 2017 (plus one by the hurricane-strength post-tropical Ophelia in Ireland):

Bret:  Trinidad (40 mph, Jun 19)
Cindy:  East of Port Arthur, TX (45 mph, Jun 22)
Emily:  Anna Maria Island, FL (45 mph, Jul 31)
Franklin: Pulticub, Mexico (60 mph, Aug 7); Lechuguillas, Mexico (85 mph, Aug 10)
Harvey:  North of Port Aransas, TX (130 mph, August 25); Holiday Beach, TX (130 mph, August 26); west of Cameron, LA (45 mph, August 30)
Irma:  Barbuda, Sint Maarten, and British Virgin Islands (185 mph, September 6); Little Inagua, Bahamas (160 mph, September , Camaguey Islands, Cuba (160 mph, September ; Cudjoe Key, FL (130 mph, September 10); Marco Island, FL (115 mph, September 10); Naples, FL (115 mph, September 10)
Katia:  North of Tecolutla, Mexico (75 mph, September
Maria:  Dominica (160 mph, September 18); Yabucoa, PR (155 mph, September 20)
Nate:  Mouth of MS River (85 mph, October 7); Biloxi, MS (85 mph, October
Ophelia:  Southwest Ireland (as near-hurricane-strength post-tropical cyclone, October 16)
Philippe:  South coast of Cuba (35 mph, October 28); Florida Everglades (45 mph, October 29)


Storm-total rainfall from Hurricane Harvey, August 24 – 31, 2017. Harvey dumped over 40” (yellow colors) in Houston, with isolated amounts in excess of 50” (pink colors) south of Houston and northwest of Port Arthur. Bron afbeelding: NOAA & Wunderground.com.
 

Highlights of the 2017 Atlantic hurricane season

Dr. Phil Klotzbach (CSU) released his end-of-the-season summary on Thursday; below are a few of his highlights, mixed in with some of my own:

• 2017 tied for 9th place for most named storms (17), tied for 8th place for hurricanes (10), tied for 3rd place for major hurricanes (6), and came in 7th place for Accumulated Cyclone Energy (226).
• The 2017 Atlantic hurricane season got off to an early start on April 20, with the formation of Tropical Storm Arlene in the remote Eastern Atlantic, about 800 miles east of the Azores Islands. Arlene was only the second Atlantic tropical storm on record to form in April, the other being Tropical Storm Ana (2003).
• Harvey’s landfall in Texas on August 25 was the first major hurricane to make continental United States landfall since Wilma in 2005, ending the record-long major hurricane landfall drought at 4323 days.
• Harvey lasted 117 hours as a named storm after Texas landfall, shattering the old record for named storm longevity after Texas hurricane landfall set by Fern (1971) at 54 hours
• Harvey broke the tropical cyclone-generated United States rainfall record. Over 60” of rain fell in Nederland, Texas, breaking the old United States record of 52” in Hawaii set by Hurricane Hiki in 1950.
• Irma’s maximum intensity of 185 mph was the greatest for an Atlantic hurricane outside of the Gulf of Mexico and Caribbean on record, and is tied as the second strongest Atlantic hurricane, topped only by Allen (1980) in the Caribbean (190 mph). Two other hurricanes have notched 185-mph winds in the Caribbean: Gilbert (1988) and Wilma (2005). The Labor Day hurricane of 1935 hit the same peak winds in the Florida Straits.
• Irma maintained an intensity of 185 mph for 37 hours – the longest any cyclone around the globe has maintained that intensity on record (old record: 24 hours set by Haiyan in 2013.)
• Irma and Harvey marked the first time that two Category 4 hurricanes have made continental United States landfall in the same year.
• Irma’s Florida Keys’ landfall pressure of 929 mb was tied with the Lake Okeechobee Hurricane of 1928 for the 7th lowest on record for a continental US hurricane.
• Irma effectively destroyed the island of Barbuda in the Leeward Islands, forcing all 1,800 inhabitants to leave, making the island unpopulated for the first time in 300 years.
• Maria’s lowest central pressure of 908 mb was the lowest on record for a hurricane in the eastern Caribbean (<=20°N, 75-60°W).
• Maria intensified 70 mph in 18 hours. Only Wilma (2005), Felix (2007) and Ike (2008) have intensified more in 18 hours.
• Maria was the first Category 5 hurricane on record to make landfall in Dominica.
• Maria was the first Category 4 hurricane to make landfall in Puerto Rico since 1932, and the strongest hurricane to make landfall in Puerto Rico since 1928.
• Maria caused the largest and longest power outage in U.S. history: an island-wide power outage for all of Puerto Rico’s 3.4 million people and the 103,000 people in the U.S. Virgin Islands. As of November 30, 35% of Puerto Rico’s 1.5 million customers still did not have power, 6% had no water service, and 27% of the island’s cell phone towers were not working. In the U.S. Virgin Islands, more than half of the residents had no power.
• Nate’s 12-hour-averaged translation speed of 28 mph was the fastest 12-hour-averaged translation speed in the Gulf of Mexico on record.
• Hurricane Ophelia was a major hurricane until it reached 18.3°W, making it the most easterly major hurricane on record.

But is the 2017 hurricane season really over?

While November 30 is the official last date of the hurricane season, the atmosphere sometimes has other ideas about when the season should really end. Since 1851, there have been eleven seasons in the Atlantic and two in the Eastern Pacific that have seen named storms form in December. Here’s a list of those seasons that have occurred since 1995:

Atlantic:
2003 – Tropical Storm Odette formed on December 4, and Tropical Storm Peter formed on December 7.
2005 – Tropical Storm Zeta formed on December 30
2007 – Tropical Storm Olga formed December 11
2013 – An Unnamed Subtropical Storm formed on December 5

Eastern Pacific:
2010 – Tropical Storm Omeka formed on December 18 (in the Central Pacific region)

Our three reliable computer models for forecasting tropical cyclone genesis—the GFS, European, and UKMET models—have not been hinting at any December tropical cyclone formation in any of their recent runs. However, sea surface temperatures are warmer than average throughout the tropical Atlantic, and we cannot dismiss the possibility that a hyperactive hurricane season like 2017 might have a Tropical Storm Sean in store for us later in December. 

Bron artikel: Wunderground.com