Extremely Active 2017 Atlantic Hurricane Season Comes to a Close

The 2017 Atlantic Hurricane Season officially ends today.  Not only was it above average, as predicted, it was the basin’s fifth most active season on record.

According to NOAA, there were seventeen named storms this season. Of these, ten developed into hurricanes and six were major hurricanes with ratings of category 3 or higher on the Saffir-Simpson Scale. An average season produces twelve named storms, six hurricanes, and three major hurricanes. It is also interesting to note that this year’s ten hurricanes developed consecutively over the course of ten weeks, marking the largest number of hurricanes to form in a row in the satellite era.

This season’s Accumulated Cyclone Energy (ACE), which measures the intensity and duration of storms, was also exceptionally high. On average, a season will post an ACE of 104 in the Atlantic. This year, according to researchers at Colorado State University, it was 226 – the seventh highest in the historical record.

Officially running from June 1 to November 30, the season got off to an early start this year. Tropical Storm Arlene was a rare pre-season storm that developed in April. Another interesting outlier was Hurricane Ophelia in October. It was the easternmost major hurricane ever observed in the Atlantic Basin and the strongest storm on record to hit the Republic of Ireland. The biggest names of the season, however, were Harvey, Irma, and Maria.

In August, Harvey made landfall in Texas as category-4 hurricane. It was the first major hurricane to hit the United States since Wilma in 2005. It was also the wettest storm on record, dumping more than 50 inches of rain in southeastern Texas. This extreme precipitation caused catastrophic flooding in the Houston area.

Hurricane Irma maintained category-5 strength winds for 37 hours before making landfall as a category-4 storm in the Florida Keys. Measuring about 425 miles in diameter, Irma was wider than the Florida peninsula and its effects were felt across the entire Sunshine state in early September.

Just two weeks later, Hurricane Maria devastated Puerto Rico. It was the third category-four hurricane to hit the US, or one of its territories, in less than a month. In 166 years of record keeping, that never happened before.

Causing so much destruction, Harvey, Irma, and Maria will likely be retired from the World Meteorological Organization’s list of storm names.

This active hurricane season was largely the result of above-average sea surface temperatures in the Atlantic and ENSO neutral to cool La Niña conditions in the Pacific. With warm water to fuel storms coupled with reduced wind shear across the Gulf of Mexico, tropical development in the Atlantic basin was essentially unhindered.

In terms of economic impact, ENKI Operations, a private research firm, estimates the property damage, clean up costs, and lost business productivity from this year’s storms to be $206 billion. That would make 2017 the costliest hurricane season on record for the US. The official tally from NOAA will not be available until early 2018.

Data: NOAA

Ex-Hurricane Ophelia Batters Ireland

The remnants of Hurricane Ophelia, the 15th named storm of the 2017 Atlantic Hurricane season, slammed the Republic of Ireland on Monday. It was the strongest storm on record to hit that country.

Ophelia peaked as a category-3 hurricane near the Azores over the weekend, becoming the most intense storm ever observed that far north and east in the Atlantic Basin. Then, it rapidly transitioned to a post-tropical storm that was labeled Ex-Hurricane Ophelia by Met Éireann, Ireland’s national weather service. This means the storm was drawing energy from the difference in air masses rather than the heat and moisture of the ocean.

Despite this technical downgrade, Ophelia still packed a punch. The storm’s powerful winds, which averaged around 57mph, uprooted trees and downed power lines. It also produced significant storm surge flooding along the country’s west coast. Officials say at least three fatalities have been reported and more than 300,000 people are without power.

At Fastnet Rock, off the coast of County Cork, a wind gust of 119mph was reported. If confirmed, it will be the fastest wind gust ever recorded in Ireland.

On the eastern side of the storm, smoke and dust from the wildfires burning in Spain and Portugal were funneled northward over the UK. This caused the sun and sky to appear red in a large part of the region.

It is not unheard of for Europe to be hit by the remnants of a hurricane. However, the storms typically travel west across the Atlantic Ocean in the Trade Winds and then re-curve to the northeast if they do not make landfall in the US, Mexico, or the Caribbean. Ophelia, however, skipped the transatlantic voyage and moved northeast toward Europe after forming southwest of the Azores.

Scientists say the storm’s rapid intensification and unusual track are the result of warmer than normal sea surface temperatures at northern latitudes and a steering current known as the mid-latitude jet stream. This current of air flows from west to east and carried the storm toward Ireland.

As the climate changes and sea surface temperatures continue to warm, the area of the ocean that supports hurricane development will likely expand northward. This will make Europe even more vulnerable to post-tropical storms.

MODIS satellite image of Ex-Hurricane Ophelia over Ireland. Credit: NASA

Hurricane Nate Slams Gulf Coast

Hurricane Nate, the 14th named storm of the 2017 Atlantic Hurricane season, made two landfalls along the US Gulf Coast this weekend. The first was near the mouth of the Mississippi River in Louisiana and the second was near Biloxi, Mississippi.

Coming ashore with 85mph winds, this category-1 hurricane generated a significant storm surge that swamped parts of the region from Louisiana to the Florida Panhandle. One of the hardest hit areas was Pascagoula, MS where a storm surge of 6.3 feet was reported. The storm also downed trees and caused widespread power outages.

Moving inland, Nate was soon downgraded to a tropical depression. However, it still spawned a number of destructive tornados from Alabama to North Carolina. They ranged in strength from EF-0 to EF-2.

Nate was the first hurricane to make landfall in Mississippi since Katrina in 2005.

Credit: NOAA/NASA GOES

Weather Lingo: ACE

There are a number of different ways to gauge a hurricane season. One of these is the Accumulated Cyclone Energy index, which is widely referred to as ACE.

It expresses the combined intensity and duration of individual cyclones and provides a measure of activity for an entire hurricane season. For a single storm, it is calculated by summing the squares of the maximum sustained wind speeds measured every six hours while they are at least tropical storm strength. This number is then divided by 10,000 to make it more user-friendly. Overall, the stronger and longer-lived a storm is, the higher its ACE value.

The ACE for a season is the sum of the ACE values from individual storms that occurred that year. NOAA considers a season with an ACE of 111 or higher to be above average, while an ACE of 66 or lower is regarded as below average.

The Atlantic hurricane season runs from June 1 through November 30.

Source: CSU

(Note: Year to date the Atlantic Basin has had 13 storms with a combined ACE of 202 and there are still two months left in the 2017 hurricane season.)

Hurricane Maria Devastates Puerto Rico

Hurricane Maria, the 13th named storm of this Atlantic Hurricane season, made landfall in Yabucoa, Puerto Rico on Wednesday morning. It was the strongest storm to hit the US Territory since 1928.

Coming ashore with sustained winds measured up to 155mph, Maria was classified as a high-end category-four hurricane. Its powerful winds sheared roofs and balconies off buildings, uprooted trees, and toppled power lines. In addition, the storm’s torrential rain unleashed devastating flooding across the island. More than 30 inches of rain was reported near Caguas, PR.

Local authorities say the entire island, home to 3.5 million people, is without power. They do not expect it to be fully restored for four to six months. This unusually lengthy timeframe is largely due to the fact that Puerto Rico is an island with rugged terrain and an electrical grid that has been crumbling for years from a lack of maintenance. The Puerto Rico Electric Power Authority, the territory’s sole provider of electricity, effectively filed for bankruptcy in July.

Before making landfall in Puerto Rico, Maria roared through the Caribbean and reached category-five strength. It battered several other islands, including the US Virgin Islands, which were still reeling from the devastation caused by Hurricane Irma less than two weeks ago. As of Thursday, the death toll from Maria stands at seventeen. But sadly, this number is expected to increase as search and rescue efforts continue across the region.

Maria was the third category-four hurricane to hit the US, or one of its territories, in less than a month. In 166 years of record keeping, this has never happened before.

Hurricane Maria moves across Puerto Rico. Credit: NOAA/NASA

Hurricane Irma Batters Entire State of Florida

Hurricane Irma, the 9th named storm of this Atlantic Hurricane season, made two landfalls in Florida on Sunday. First, its eye crossed Cudjoe Key, just east of Key West, as a category-4 hurricane. Then, a few hours later,  it came ashore at Marco Island on the state’s Gulf Coast as a category-3 storm.

Measuring about 425 miles in diameter, Irma was wider than the Florida peninsula and its effects were felt across the entire Sunshine state. Powerful winds, heavy rain, and storm surge flooding caused catastrophic property damage in the Keys and along both coasts.

In the west, Naples, FL experienced wind gusts up to 142mph – the strongest recorded during the storm. On the east coast, gusts were clocked up to 109mph in the Miami/Fort Lauderdale area, where three high-rise construction cranes collapsed in the strong winds. The storm surge in both Biscayne Bay and Naples was about four feet above normal tide levels.  In the hard hit Keys, according to FEMA, 25% of homes were completely destroyed and about 65% sustained serious damage.

Reports of toppled trees and downed power lines are widespread. The Department of Homeland Security says 15 million people lost power, making it one of the largest power outages in US history.

Moving north and shifting inland, Irma was downgraded to a tropical storm on Monday. Nevertheless, it continued to pack a powerful punch. Jacksonville, FL reported a record six-foot storm surge and the worst flooding it has seen since Hurricane Dora moved through the area in 1964.

Irma’s wrath was also felt in parts of Georgia and the Carolinas. Along the coast, storm surge flooding inundated communities from Savannah, GA to Charleston, SC. Further inland, the NWS issued its first ever tropical storm warning for the metro-Atlanta area.

Coming just sixteen days after Hurricane Harvey, Irma was the second category-4 storm to make landfall in the US this season. In 166 years of record keeping, never before have two Atlantic hurricanes of such intensity hit this country during the same year.

The death toll from this historic storm currently stands at forty-three, including five fatalities reported in Florida, three in Georgia, and one in South Carolina. The rest are from the Caribbean, where Irma hit multiple islands as a Category 5 storm late last week. Sadly, these numbers are expected to rise as search and rescue efforts continue. The entire region faces a long and expensive road to recovery ahead.

Hurricane Irma makes landfall in southern Florida as a Category-4 storm. Credit: NASA

Hurricane Irma Challenges Multiple Records

Hurricane Irma’s final chapters have yet to be written, but the storm has already earned its place in the history books.

According to NOAA, Irma’s winds peaked at 185 mph. That means it is tied as the second strongest hurricane ever recorded in the Atlantic Basin. It shares this dubious honor with the Labor Day /Florida Keys Hurricane of 1935, Hurricane Gilbert of 1988, and Hurricane Wilma of 2005. Only Hurricane Allen in 1980 was stronger with winds clocked at 190 mph. That said, Irma now ranks as the strongest storm on record in the Atlantic outside of the Carribean Sea and the Gulf of Mexico.

Irma’s winds remained at 185 mph for 37 hours. That is the longest any storm on the planet has maintained that level of intensity. The previous record of 24 hours was set by Super Typhoon Haiyan in the northwest Pacific in 2013. Furthermore, Irma remained a Category 5 hurricane for three consecutive days, the longest such measurement since the satellite era began in 1966.

Source: NHC

Harvey Sets New Rainfall Record for Continental US

Battering southeast Texas for days, Tropical Storm Harvey has produced more rainfall than any other single storm on record in the contiguous United States.

According to the NWS, 51.88 inches of rain was reported at a gauge near Mont Belvieu at Cedar Bayou, about 40 miles east of Houston. This crushes the previous record of 48 inches that was set by Tropical Storm Amelia which hit Medina, TX in 1978.

The record for the entire US, however, still stands. It was set in 1950 when Hurricane Hiki dropped 52 inches of rain on Hawaii.

Source: NWS

Harvey Unleashes Catastrophic Flooding in Houston

Days after making landfall as a category-4 hurricane, Harvey, now a tropical storm, is still battering southeast Texas. Relentless rain has unleashed catastrophic flooding across the region, including Houston – this country’s fourth largest city.

While this devastating event is still unfolding, rainfall totals in some areas have already exceeded two feet. Dayton, TX, northeast of Houston, has reported a staggering 39.72 inches of rain since Thursday. Houston Intercontinental Airport (IAH) has posted 25.66 inches of rain so far and reported its wettest calendar day on record on Sunday with 16.07 inches.

This intense rainfall is causing the many rivers, creeks, and bayous in the metro Houston area to overflow their banks and flood homes, businesses, and major roadways – effectively paralyzing the area. Rainfall rates reached as high as 3 inches per hour on Sunday in some areas, prompting the NWS to issue a flash flood emergency – the highest level of a flood alert.

No evacuation order was issued ahead of the storm in Houston and residents were told to shelter in place. Now, thousands of high water rescues are taking place via boat and helicopter to save people trapped in their homes. The situation has many people comparing it to scenes that played out in the aftermath of Hurricane Katrina in New Orleans. The mayor of Houston, Sylvester Turner, has opened the massive George R. Brown Convention Center to be used as a shelter. As of Monday, eight storm-related deaths have been reported. But sadly, local authorities expect this number to increase as the water continues to rise.

Southeast Texas is no stranger to flooding. However, officials in Houston say this event is the worst they have seen since Tropical Storm Allison in 2001. That storm dumped more than 35 inches of rain on the metro area over the course of five days and caused $5 billion worth of damage.

Harvey, wedged between two areas of high pressure, is expected to linger over the region for several more days and dump an additional 15 to 25 inches of rain. Forecasters at the NWS say the rainfall total for this storm could reach an unprecedented 50 inches in some spots.

Eighteen counties in Texas, according to Governor Greg Abbot, have been declared federal disaster areas because of this storm.

TS Harvey caused unprecedented flooding in Houston, TX. Credit: Aryan Midas

Hurricane Harvey Hammers Texas

Hurricane Harvey, the eighth named storm of the 2017 Atlantic Hurricane Season, made landfall in Rockport, TX late Friday night. It was the strongest storm to hit the United States in twelve years.

Coming ashore with winds measured up to 130mph, Harvey was classified as a Category-4 hurricane on the Saffir-Simpson Scale. These powerful winds along with storm surge flooding and torrential rain caused catastrophic property damage across the Texas Coastal Bend region. It also downed trees and left hundreds of thousands of people without power. To date, according to local officials, only two storm-related deaths have been reported.

Moving inland, toward Houston, Harvey weakened to a Tropical Storm on Saturday afternoon. However, despite this downgrade in wind speed, its rain bands are still drawing moisture from the Gulf of Mexico and unleashing massive amounts of precipitation. Wedged between two areas of high pressure, the storm is essentially stalled over the region. Therefore, even more flooding rain is expected over the next several days.

Harvey was the first major hurricane – category 3 or higher – to make landfall in the Lone Star State since Hurricane Carla in September 1961.

Satellite imagery from NOAA shows Hurricane Harvey along the Texas Coast. Credit: NOAA