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Hurricane Gert (1999)
Encyclopedia
Hurricane Gert was the fourth of five major hurricanes in the moderately active 1999 Atlantic hurricane season
. A Cape Verde-type hurricane, Gert formed on September 11 off the coast of Africa
before heading west-northwest. It reached a peak wind speed of 150 mph (240 km/h) by September 15 over the open central Atlantic east-northeast of the Leeward Islands
. It gradually curved to the northwest and later to the north, due to a weakness in the subtropical ridge created by Hurricane Floyd
. Hurricane Gert passed east of Bermuda
on September 21 and began a steady weakening trend at that time. It turned to the northeast, and on September 23, Gert transitioned into an extratropical cyclone
to the southeast of Atlantic Canada
before being absorbed by a larger storm.
For several days, Gert threatened to strike Bermuda, prompting the evacuation of tourists. Although Gert's center did not make landfall, it passed a short distance east of the island, producing hurricane force winds that left 11,000 people without power. High waves swept two people out to sea at Acadia National Park
in Maine
. Later, strong waves struck Newfoundland and left heavy marine damage.
moved off the coast of Africa
on September 10, with evidence of a low-level circulation
and convective banding. It moved west-northwestward, located south of a subtropical ridge
. Based on satellite imagery, it is estimated the system organized into Tropical Depression Nine by 1200 UTC
on September 11 to the south of the Cape Verde
islands. Upon its formation, the center was poorly-defined, with restricted easterly outflow
due to easterly wind shear
. After about 24 hours of remaining somewhat disorganized, the convection became more concentrated on September 12 as banding features and outflow improved. Consequently, the National Hurricane Center
(NHC) upgraded the depression to Tropical Storm Gert, the seventh named storm
of the season.
After becoming a tropical storm, Gert quickly intensified due to the presence of an anticyclone
aloft, as well as warm water temperatures exceeding 84º F (29º C). Following the development of a warm spot
near the center, Gert intensified into a hurricane on September 13. It strengthened further, developing an eye that briefly dissipated before reforming. Early on September 15, Gert attained major hurricane
strength, or a Category 3 on the Saffir-Simpson scale
. Still moving west-northwestward, Gert continued its steady intensification trend, developing well-defined outflow throughout the circulation that was described as "outstanding". After reaching Category 4 status on September 15, Gert strengthened further to peak winds of 130 mph (209.2 km/h) early on September 16, as estimated on satellite imagery through the Dvorak technique
. Satellite intensity estimates reached as high as 160 mph (257.5 km/h), or a Category 5 hurricane. At the time, the hurricane was located about 720 mi (1160 km) east-northeast of Guadeloupe
in the Lesser Antilles
. Around the time of peak intensity, Gert maintained a round central dense overcast. Hurricane Hunters
investigated the hurricane on September 16 and indicated a slight weakening trend due to an eyewall replacement cycle
. Gradually Gert turned toward the northwest due to a weakness in the subtropical ridge, created by Hurricane Floyd
to the west. As it did so, the hurricane re-intensified briefly before resuming a weakening trend, due to increased wind shear and an upper-level trough
to its west restricting outflow.
After weakening to winds of 120 mph (193.1 km/h), Gert again re-strengthened to Category 4 status on September 19, as the eye became well-organized within its surrounding convection following an eyewall replacement cycle. By September 20, while the hurricane was approaching Bermuda
, the appearance became more ragged due to the intrusion of unfavorable dry air. Early on September 21 Gert weakened to Category 2 intensity, around the same time it turned northward. Later that day it passed about 135 mi (217.3 km) east of Bermuda, producing hurricane force winds on the island. Steady weakening continued as Gert accelerated northeastward under the influence of an approaching trough. The convection decreased around the center due to cooler water temperatures, and on September 23 Gert weakened to tropical storm status as it approached Newfoundland. After nearly all of the convection had dissipated, the system no longer met the characteristics of a tropical cyclone. As a result, it was declared extratropical
at 1200 UTC on September 23 about 55 mi (90 km) southeast of Cape Race
, Newfoundland. About six hours later, the remnants of Gert were absorbed by a larger extratropical storm. Gert was the fourth of five Category 4 hurricanes to form during the 1999 season, the highest number of such storms on record. Later, the 2005
season tied the record.
and hurricane watch was issued for the island on September 19, about two days prior to its closest approach. As Gert moved closer to the island, the watch and warning were replaced by a hurricane warning on September 20, which was maintained until the following day after Gert moved further away. Before Gert passed by the island, officials closed two schools and converted them to emergency shelters. Police workers advised 700 families to leave their houses. Cruise lines diverted ships away, while hundreds of tourists took flights to leave the island.
While passing east of Bermuda, Gert produced 10-minute sustained winds of 45 mph (72.4 km/h) at Bermuda International Airport
. Elsewhere on the island, wind gusts peaked at 87 mph (140 km/h) along the coast, while 1-minute sustained winds reached 80 mph (130 km/h) along the harbor. Rainfall on the island was light, totaling only 0.53 in (13.5 mm). Rough surf battered the island, resulting in extensive beach erosion. The well-known Natural Arches were damaged, and part of a house collapsed into the sea. During the storm, a dolphin pool was destroyed, injuring the animals; they later escaped captivity into the Atlantic Ocean. Severe damage was reported along the southern shore of the island. Approximately 11,000 residents suffered temporary power outages. Several roads were flooded, and the intense winds downed trees. However, the storm's worst effects remained offshore.
along the coast of Maine
. The crew of a lobster boat later found their bodies. Although the storm never approached the United States, seas in the area generally ran 3 to 5 ft (0.9144 to 1.5 m) above normal.
Late in its duration, Gert passed just southeast of Newfoundland before becoming extratropical, producing wave heights of 77.4 ft (23.6 m) offshore and 30 ft (9 m) onshore. In St. Bride's
along the Avalon Peninsula
, a large wave severely damaged a wharf, destroying five boats and damaging 45 others. Along the wharf, a wave swept three people into the ocean, hospitalizing one of them. The wharf required $2 million (1999 CAD
, $1.9 million 1999 USD) in repairs, forcing its closure. Further west, high waves damaged a fish plant in Lord's Cove. Gale force winds extended across southeastern Newfoundland, and in the Grand Banks
a station reported winds of 74 mph (120 km/h). Onshore, the winds downed trees and caused power outages, primarily in the St. John's area
. In addition, the adverse conditions from Gert prompted the cancellation of flights to and from St. John's International Airport
.
1999 Atlantic hurricane season
The 1999 Atlantic hurricane season officially began on June 1, 1999, and lasted until November 30, 1999. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin....
. A Cape Verde-type hurricane, Gert formed on September 11 off the coast of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
before heading west-northwest. It reached a peak wind speed of 150 mph (240 km/h) by September 15 over the open central Atlantic east-northeast of the Leeward Islands
Leeward Islands
The Leeward Islands are a group of islands in the West Indies. They are the northern islands of the Lesser Antilles chain. As a group they start east of Puerto Rico and reach southward to Dominica. They are situated where the northeastern Caribbean Sea meets the western Atlantic Ocean...
. It gradually curved to the northwest and later to the north, due to a weakness in the subtropical ridge created by Hurricane Floyd
Hurricane Floyd
Hurricane Floyd was the sixth named storm, fourth hurricane, and third major hurricane in the 1999 Atlantic hurricane season. Floyd triggered the third largest evacuation in US history when 2.6 million coastal residents of five states were ordered from their homes as it approached...
. Hurricane Gert passed east of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
on September 21 and began a steady weakening trend at that time. It turned to the northeast, and on September 23, Gert transitioned into an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
to the southeast of Atlantic Canada
Atlantic Canada
Atlantic Canada is the region of Canada comprising the four provinces located on the Atlantic coast, excluding Quebec: the three Maritime provinces – New Brunswick, Prince Edward Island, and Nova Scotia – and Newfoundland and Labrador...
before being absorbed by a larger storm.
For several days, Gert threatened to strike Bermuda, prompting the evacuation of tourists. Although Gert's center did not make landfall, it passed a short distance east of the island, producing hurricane force winds that left 11,000 people without power. High waves swept two people out to sea at Acadia National Park
Acadia National Park
Acadia National Park is a National Park located in the U.S. state of Maine. It reserves much of Mount Desert Island, and associated smaller islands, off the Atlantic coast...
in Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
. Later, strong waves struck Newfoundland and left heavy marine damage.
Meteorological history
A tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
moved off the coast of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
on September 10, with evidence of a low-level circulation
Atmospheric circulation
Atmospheric circulation is the large-scale movement of air, and the means by which thermal energy is distributed on the surface of the Earth....
and convective banding. It moved west-northwestward, located south of a subtropical ridge
Subtropical ridge
The subtropical ridge is a significant belt of high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere. It is characterized by mostly calm winds, which acts to reduce air quality under its axis by causing fog overnight, and haze during...
. Based on satellite imagery, it is estimated the system organized into Tropical Depression Nine by 1200 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
on September 11 to the south of the Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
islands. Upon its formation, the center was poorly-defined, with restricted easterly outflow
Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather...
due to easterly wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
. After about 24 hours of remaining somewhat disorganized, the convection became more concentrated on September 12 as banding features and outflow improved. Consequently, the National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
(NHC) upgraded the depression to Tropical Storm Gert, the seventh named storm
Tropical cyclone naming
Tropical cyclones have officially been named since 1945 and are named for a variety of reasons, which include to facilitate communications between forecasters and the public when forecasts, watches, and warnings are issued. Names also reduce confusion about what storm is being described, as more...
of the season.
After becoming a tropical storm, Gert quickly intensified due to the presence of an anticyclone
Anticyclone
An anticyclone is a weather phenomenon defined by the United States' National Weather Service's glossary as "[a] large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere"...
aloft, as well as warm water temperatures exceeding 84º F (29º C). Following the development of a warm spot
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
near the center, Gert intensified into a hurricane on September 13. It strengthened further, developing an eye that briefly dissipated before reforming. Early on September 15, Gert attained major hurricane
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
strength, or a Category 3 on the Saffir-Simpson scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
. Still moving west-northwestward, Gert continued its steady intensification trend, developing well-defined outflow throughout the circulation that was described as "outstanding". After reaching Category 4 status on September 15, Gert strengthened further to peak winds of 130 mph (209.2 km/h) early on September 16, as estimated on satellite imagery through the Dvorak technique
Dvorak technique
The Dvorak technique is a widely used system to subjectively estimate tropical cyclone intensity based solely on visible and infrared satellite images. Several agencies issue Dvorak intensity numbers for cyclones of sufficient intensity...
. Satellite intensity estimates reached as high as 160 mph (257.5 km/h), or a Category 5 hurricane. At the time, the hurricane was located about 720 mi (1160 km) east-northeast of Guadeloupe
Guadeloupe
Guadeloupe is an archipelago located in the Leeward Islands, in the Lesser Antilles, with a land area of 1,628 square kilometres and a population of 400,000. It is the first overseas region of France, consisting of a single overseas department. As with the other overseas departments, Guadeloupe...
in the Lesser Antilles
Lesser Antilles
The Lesser Antilles are a long, partly volcanic island arc in the Western Hemisphere. Most of its islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean, with the remainder located in the southern Caribbean just north of South America...
. Around the time of peak intensity, Gert maintained a round central dense overcast. Hurricane Hunters
Hurricane Hunters
The Hurricane Hunters are aircraft that fly into tropical cyclones in the North Atlantic Ocean and Northeastern Pacific Ocean for the specific purpose of directly measuring weather data in and around those storms. In the United States, the Air Force, Navy, and NOAA units have all participated in...
investigated the hurricane on September 16 and indicated a slight weakening trend due to an eyewall replacement cycle
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
. Gradually Gert turned toward the northwest due to a weakness in the subtropical ridge, created by Hurricane Floyd
Hurricane Floyd
Hurricane Floyd was the sixth named storm, fourth hurricane, and third major hurricane in the 1999 Atlantic hurricane season. Floyd triggered the third largest evacuation in US history when 2.6 million coastal residents of five states were ordered from their homes as it approached...
to the west. As it did so, the hurricane re-intensified briefly before resuming a weakening trend, due to increased wind shear and an upper-level trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
to its west restricting outflow.
After weakening to winds of 120 mph (193.1 km/h), Gert again re-strengthened to Category 4 status on September 19, as the eye became well-organized within its surrounding convection following an eyewall replacement cycle. By September 20, while the hurricane was approaching Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
, the appearance became more ragged due to the intrusion of unfavorable dry air. Early on September 21 Gert weakened to Category 2 intensity, around the same time it turned northward. Later that day it passed about 135 mi (217.3 km) east of Bermuda, producing hurricane force winds on the island. Steady weakening continued as Gert accelerated northeastward under the influence of an approaching trough. The convection decreased around the center due to cooler water temperatures, and on September 23 Gert weakened to tropical storm status as it approached Newfoundland. After nearly all of the convection had dissipated, the system no longer met the characteristics of a tropical cyclone. As a result, it was declared extratropical
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
at 1200 UTC on September 23 about 55 mi (90 km) southeast of Cape Race
Cape Race
Cape Race is a point of land located at the southeastern tip of the Avalon Peninsula on the island of Newfoundland, Canada. Its name is thought to come from the original Portuguese name for this cape, "Raso", or "bare"...
, Newfoundland. About six hours later, the remnants of Gert were absorbed by a larger extratropical storm. Gert was the fourth of five Category 4 hurricanes to form during the 1999 season, the highest number of such storms on record. Later, the 2005
2005 Atlantic hurricane season
The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion...
season tied the record.
Bermuda
As Gert was several days away from Bermuda, the NHC advised residents there to monitor the progress of the storm, Due to uncertainties in the future forecast, as well as the size and strength of Gert, a tropical storm warningTropical cyclone warnings and watches
Warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate...
and hurricane watch was issued for the island on September 19, about two days prior to its closest approach. As Gert moved closer to the island, the watch and warning were replaced by a hurricane warning on September 20, which was maintained until the following day after Gert moved further away. Before Gert passed by the island, officials closed two schools and converted them to emergency shelters. Police workers advised 700 families to leave their houses. Cruise lines diverted ships away, while hundreds of tourists took flights to leave the island.
While passing east of Bermuda, Gert produced 10-minute sustained winds of 45 mph (72.4 km/h) at Bermuda International Airport
Bermuda International Airport
L.F. Wade International Airport , formerly named Bermuda International Airport, is the sole airport serving Bermuda, a British overseas territory in the North Atlantic Ocean. It is located in the parish of St. George's and is northeast of Bermuda's capital city of Hamilton. In 2006, L.F. Wade...
. Elsewhere on the island, wind gusts peaked at 87 mph (140 km/h) along the coast, while 1-minute sustained winds reached 80 mph (130 km/h) along the harbor. Rainfall on the island was light, totaling only 0.53 in (13.5 mm). Rough surf battered the island, resulting in extensive beach erosion. The well-known Natural Arches were damaged, and part of a house collapsed into the sea. During the storm, a dolphin pool was destroyed, injuring the animals; they later escaped captivity into the Atlantic Ocean. Severe damage was reported along the southern shore of the island. Approximately 11,000 residents suffered temporary power outages. Several roads were flooded, and the intense winds downed trees. However, the storm's worst effects remained offshore.
United States and Canada
On September 20, Hurricane Gert was attributed to generating a rogue wave that swept two people out to sea at Acadia National ParkAcadia National Park
Acadia National Park is a National Park located in the U.S. state of Maine. It reserves much of Mount Desert Island, and associated smaller islands, off the Atlantic coast...
along the coast of Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
. The crew of a lobster boat later found their bodies. Although the storm never approached the United States, seas in the area generally ran 3 to 5 ft (0.9144 to 1.5 m) above normal.
Late in its duration, Gert passed just southeast of Newfoundland before becoming extratropical, producing wave heights of 77.4 ft (23.6 m) offshore and 30 ft (9 m) onshore. In St. Bride's
St. Bride's, Newfoundland and Labrador
St. Bride's is a small town on the Cape Shore of Newfoundland, Canada. Located 166 km Southwest of the capital of Newfoundland and Labrador, St. John's, St. Bride's is a fishing community with a population of approximately 450 persons. The largest codfish ever caught, weighing in at...
along the Avalon Peninsula
Avalon Peninsula
The Avalon Peninsula is a large peninsula that makes up the southeast portion of the island of Newfoundland.The peninsula is home to 257,223 people, which is approximately 51% of Newfoundland's population in 2009, and is the location of the provincial capital, St. John's. It is connected to the...
, a large wave severely damaged a wharf, destroying five boats and damaging 45 others. Along the wharf, a wave swept three people into the ocean, hospitalizing one of them. The wharf required $2 million (1999 CAD
Canadian dollar
The Canadian dollar is the currency of Canada. As of 2007, the Canadian dollar is the 7th most traded currency in the world. It is abbreviated with the dollar sign $, or C$ to distinguish it from other dollar-denominated currencies...
, $1.9 million 1999 USD) in repairs, forcing its closure. Further west, high waves damaged a fish plant in Lord's Cove. Gale force winds extended across southeastern Newfoundland, and in the Grand Banks
Grand Banks
The Grand Banks of Newfoundland are a group of underwater plateaus southeast of Newfoundland on the North American continental shelf. These areas are relatively shallow, ranging from in depth. The cold Labrador Current mixes with the warm waters of the Gulf Stream here.The mixing of these waters...
a station reported winds of 74 mph (120 km/h). Onshore, the winds downed trees and caused power outages, primarily in the St. John's area
St. John's, Newfoundland and Labrador
St. John's is the capital and largest city in Newfoundland and Labrador, and is the oldest English-founded city in North America. It is located on the eastern tip of the Avalon Peninsula on the island of Newfoundland. With a population of 192,326 as of July 1, 2010, the St...
. In addition, the adverse conditions from Gert prompted the cancellation of flights to and from St. John's International Airport
St. John's International Airport
St. John's International Airport is an international airport located northwest of St. John's, Newfoundland and Labrador, Canada that serves the St. John's Metro Area and the Avalon Peninsula. The airport is part of the National Airports System, and is operated by St...
.