Tuesday, December 9, 2014

2014 Season Summary

The 2014 Atlantic Hurricane Season had below-average activity, with a total of

9 cyclones attaining tropical depression status,
8 cyclones attaining tropical storm status,
6 cyclones attaining hurricane status, and
2 cyclones attaining major hurricane status.

Before the beginning of the season, I predicted that there would be

13 cyclones attaining tropical depression status,
12 cyclones attaining tropical storm status,
4 cyclones attaining hurricane status, and
1 cyclone attaining major hurricane status.

The season was in fact below-average, particularly in number of named storms (8) which was well below the 30 year average (12) and what I predicted. In addition, the season had the fewest named storms since the 1997 season. The number of hurricanes and major hurricanes were closer to average, and were higher than my predictions.

A weak El Nino event did develop by late spring of 2014, contributing to stronger upper-level winds across the Atlantic basin and inhibiting development. In addition, though sea surface temperatures were anomalously warm over the subtropical Atlantic basin, SST values remained near average closer to the equator; the Gulf of Mexico even trended below average during parts of the season, limiting development there (Tropical Storm Dolly was the only tropical storm-strength cyclone to exist there).

Adding to these factors was a near- to below-normal West African monsoon, which made tropical waves emerging into the east Atlantic less frequent and vigorous. Stable air over the Atlantic itself also inhibited cyclone formation. In contrast, the East Pacific basin had above-average activity, consistent with the presence of an El Nino. Most land areas in the Atlantic were spared significant damage this season, with only tropical storm landfalls in Mexico, Central America, and the eastern Caribbean, and a single landfalling hurricane, Hurricane Arthur, in the United States. A notable exception to this was Bermuda, which was hit directly by two hurricanes in a very short span (see below).

Some other notable facts and statistics concerning this season are:

  • Hurricane Gonzalo was the strongest storm of the season, a category 4 hurricane with 145 mph winds and a minimum pressure of 940 mb, making it the strongest Atlantic cyclone since Hurricane Igor of 2010
  • Hurricane Arthur made landfall in North Carolina on July 3 (EDT), making it the earliest in a season a hurricane has ever made landfall in the state
  • Hurricane Fay and Hurricane Gonzalo directly hit Bermuda on October 12 (Fay was a tropical storm at the time) and October 17, respectively, an unprecedented two direct hits in a six-day period for the island
  • Tropical Storm Hanna formed from the remnants of Tropical Storm Trudy of the East Pacific basin, which had made landfall in Mexico on October 18, dissipated, and crossed into the Gulf of Mexico

Overall, the 2014 Atlantic Hurricane Season was quiet, showing consistency with pre-season forecasts.

Sources: http://www.esrl.noaa.gov/psd/enso/mei/, http://www.ncdc.noaa.gov/teleconnections/enso/indicators/sea-temp-anom.php, http://www.noaanews.noaa.gov/stories2014/20141124_hurricaneseasonwrapup_2014.html

Wednesday, October 22, 2014

Tropical Storm Hanna (2014)

Storm Active: October 21-22, 27

On October 17, Tropical Storm Trudy formed in the eastern Pacific basin. The next day, it made landfall in Mexico and quickly dissipated over the mountainous terrain. On October 19, a low pressure system began to form over the Bay of Campeche from the remnants of Trudy. Producing scattered shower activity throughout the southwestern Gulf of Mexico, the system slowly meandered to the east-northeast and moved farther over water over the next few days. During the day of October 21, the low deepened significantly and gained definition, though the associated convection did not yet meet the criteria of a tropical cyclone. That night, however, a small but persistent area of thunderstorm activity developed near the center of circulation, and the system was designated Tropical Depression Nine.

Despite being over warm water, the system faced unfavorable atmospheric conditions, including shear out of the west and interaction with a frontal boundary to its northeast. This front caused heavy rain across the northern Yucatan through Cuba and the neighboring islands, but this moisture was not associated with Nine. On October 22, the system turned east-southeast towards the Mexican coast. Failing to strengthen, the system made landfall that evening as a weak tropical depression, and was downgraded to a remnant low just a few hours afterward.

On October 24, the system emerged over water on the eastern side of the Yucatan peninsula and began to drift generally east-southeast. Though atmospheric conditions were unfavorable, the low maintained its identity for the next few days, and concentrated thunderstorm activity reappeared during the day of October 26. By this time, the system had changed tack and was drifting westward toward the coast of Honduras. On the morning of October 27, despite the fact that a portion of the circulation was interacting with land, the low was producing gale force winds and had acquired an organized convective structure. It was therefore upgraded to Tropical Storm Hanna.

A few hours later, the center moved inland over northeastern Nicaragua. Hanna quickly lost definition and was downgraded to a tropical depression that evening. It then degenerated into a remnant low as it moved west-southwestward over the mountainous terrain of Central America. Despite this, heavy rains continued over portions of northern Nicaragua and southern Honduras, bringing 3-5 inches to many areas. On October 28, the low moved northwestward and emerged into the Gulf of Honduras, but it once again made landfall in Belize early on the 29th, eliminating any chance of redevelopment. Tropical moisture associated with Hanna eventually made it as far as the southwestern United States.

The above image shows Hanna on October 27, a few hours after regeneration into a tropical cyclone.

Despite mostly favorable conditions, Hanna did not significantly intensify during its lifetime due to land interaction.

Sources: http://upload.wikimedia.org/wikipedia/commons/0/01/Hanna_Oct_27_2014_1600Z.jpg, http://upload.wikimedia.org/wikipedia/commons/6/63/Hanna_2014_track.png

Sunday, October 12, 2014

Hurricane Gonzalo (2014)

Storm Active: October 12-19

During the first week of October, a tropical wave entered the eastern Atlantic and tracked generally westward. It did not show signs of organization until October 10, when shower activity began to increase in concentration. Despite a large mass of dry air to its north, the disturbance developed rapidly. On October 12, curved bands became evident around a well-defined center of circulation. Since aircraft data indicated that gale-force winds were occurring in the vicinity of the center, the system was designated Tropical Storm Gonzalo early that afternoon.

Situated over an environment of warm water, unstable air, and low wind shear, only dry air slightly slowed development. Convective bands wrapped around a primitive eye feature that evening and steady strengthening began. Meanwhile, a trough to the north of the system steered it westward toward the Leeward Islands. During the morning of October 13, Gonzalo's center passed among these islands, bringing tropical storm conditions to much of the region as it continued to intensify and deepen. Later that day, the system turned to the northwest and gained enough organization to be upgraded to a hurricane as it passed near the Virgin Islands. Though the center passed to the east, the large area of deep convection associated with Gonzalo stretched as far as Puerto Rico.

As the hurricane exited the Caribbean overnight, an eye began to consistently appear on satellite imagery. Pressures continued to decline, and the system underwent rapid intensification through the morning of October 14. Though the convection remained somewhat lopsided (with most of the deep convection south of the eye), Gonzalo became the second major hurricane of the 2014 season later that day. Meanwhile, the cyclone continued to round the edge of a ridge to its north, and its motion gradually turned poleward. The eye contracted during the morning of October 15, indicating that an eyewall replacement cycle had begun and stabilizing Gonzalo's intensity as a low-end Category 4 hurricane. Gonzalo was the first category 4 hurricane to form in the Atlantic since 2011's Ophelia.

As is usual in such cycles, the cyclone's eye clouded over late that morning as an outer eyewall formed, and internal dynamics caused Gonzalo to weaken slightly over the following 12 hours. Overnight, the system completed its northward turn and its eyewall replacement, with a large, symmetrical eye forming by the morning of October 16. Meanwhile, the banding structure and outflow had also improved, and Gonzalo restrengthened into a category 4. Later that day, the system reached its peak intensity of 145 mph winds and a minimum pressure of 940 mb before the inner core was once again disrupted that evening, leading to gradual weakening. Caught in a south-southwesterly flow, the cyclone also began to accelerate to the north-northeast toward Bermuda that evening.

By the morning of October 17, conditions were deteriorating in Bermuda, as outer bands began to sweep across the island. During the afternoon, the Gonzalo's eye reappeared, and weakening temporarily ceased, with the cyclone at category 3 hurricane strength. Around 8:30 pm EDT that evening, the center of the hurricane passed directly over Bermuda bringing significant storm surge to the coastline as well as sustained winds to hurricane force. During that evening, upper-level winds increased somewhat, putting Gonzalo on a steady weakening trend as it accelerated away from Bermuda.

The cyclone moved north of the Gulf stream during the morning of October 18, and convection began to disappear from the southern half of the circulation. As a result, the system weakened to a category 1 hurricane. Despite plummeting ocean temperatures however, Gonzalo maintained a well-defined eyewall through that evening. Overnight, the system sped past offshore of Newfoundland, causing gusty winds with its broadening windfield. By the morning of October 19, Gonzalo was racing northeast across the northern Atlantic at forward speed of over 50 mph. The cyclone finally became extratropical above 50°N that afternoon. The system subsequently passed near the United Kingdom on October 21 before being absorbed near the Arctic Circle.

Gonzalo experienced several fluctuations in intensity as a major hurricane due to internal dynamics. Even in the above image, a concentric set of eyeballs seems to be forming.

Remarkably, both Tropical Storm Fay and Hurricane Gonzalo passed very near or directly over Bermuda over the course within a period of less than one week!

Sources: http://upload.wikimedia.org/wikipedia/commons/7/7a/Gonzalo_Oct_16_2014_1745Z.jpg, http://upload.wikimedia.org/wikipedia/commons/1/18/Gonzalo_2014_track.png

Friday, October 10, 2014

Hurricane Fay (2014)

Storm Active: October 10-13

Around October 8, persistent shower and thunderstorm activity appeared in conjunction with a low pressure system located northeast of the Windward Islands. As the low moved west-northwestward over the following day, environmental conditions improved. On October 9, the trough associated with the circulation center became visibly curved with the development of a semicircular rain band about the low's north and east sides. Meanwhile, surface pressures continued to fall, and the circulation became much better defined by the morning of October 10. At this time, the system was organized enough to be designated Subtropical Depression Seven.

Through the evening, an area of deeper convection within the rain band developed northwest of the center. Since aircraft reconnaissance data indicated that higher winds were occurring in this area, the intensity of the system increased significantly, and Seven was upgraded to Subtropical Storm Fay. By the morning of October 11, Fay had come to the western edge of a subtropical ridge and had assumed a northward motion toward Bermuda. In addition, the area of deep convection moved close enough to the center and became symmetrical enough that Fay transitioned to a tropical storm that same morning.

Later that day, despite moderate shear aloft, the convective canopy covered Fay's center for the first time. The central pressure continued to drop meanwhile, and Fay intensified to near-hurricane strength. By this time, conditions were rapidly deteriorating in Bermuda. Early in the morning on October 12, the center of the cyclone passed almost directly over Bermuda, bringing winds gusting to hurricane strength, 3-5 inches of rain, and large sea swells. The system continued to curve to the east and accelerate as it passed the island that day. During the afternoon, Fay briefly developed a small eye, and became more symmetrical as shear temporarily lessened. As a result, the cyclone was upgraded to a minimal hurricane and reached its peak intensity of 75 mph winds and a pressure of 986 mb.

During the evening and overnight, however, wind shear increased substantially, quickly weakening the system back below hurricane strength and displacing its convection to the northeast of the center. On October 13, a frontal boundary moving off of the United States was steering Fay nearly due east, and the interactions between the two systems contributed to the tropical storm's dissipation later that day. The remnant vortex of Fay became embedded in the same front by the afternoon.

The above image shows Fay passing near Bermuda on October 12.

Fay's track includes square points, indicating a time at which the cyclone was subtropical.

Sources: http://upload.wikimedia.org/wikipedia/commons/a/a9/Fay_Oct_12_2014_1455Z.jpg, http://upload.wikimedia.org/wikipedia/commons/8/83/Fay_2014_track.png

Thursday, September 11, 2014

Hurricane Edouard (2014)

Storm Active: September 11-19

On September 7, a tropical low emerged off of the coast of Africa, already showing signs of organization as it moved west. Though a broad circulation was evident in association with the system from the beginning, convection remained decentralized through the next few days. On September 8, the system passed to the well south of the Cape Verde Islands, with minimal impacts. At the same time, the low began a gradual turn toward the northwest, exploiting a weakness in the Bermuda High. Upper-level winds prevented development through September 10. Thereafter, shear abated, allowing the low to acquire organization. By the morning of September 11, the appearance of banding features and a better-defined circulation merited the classification of the system as Tropical Depression Six.

Overnight, denser convection developed near the center, and the cyclone was upgraded to Tropical Storm Edouard. Meanwhile, vertical shear kept the center near the southwestern edge of the convective canopy. The circulation of Edouard gained definition over the next day, leading to some modest intensification as the central pressure dropped and the outflow improved. Even though September 13, however, dry air continued to enter the system from the south, fighting the development of a central dense overcast. But upper-level winds continued to become more favorable and waters were anomalously warm, resulting in continued strengthening. During the morning of September 14, an eye made a brief appearance on visual imagery, and Edouard was upgraded to a category 1 hurricane.

During that day, only the entrainment of dry air, which disrupted the formation of a full eyewall, prevented the rapid intensification of the cyclone. Still, the central pressure dropped considerably that evening and overnight. By the morning of September 15, Edouard had become a category 2 hurricane. Later that day, the system began to navigate around the western edge of a subtropical ridge and assumed a more poleward motion. Edouard developed a larger and more symmetric eye during the afternoon while rain bands extended farther from the center, especially on the western side of the circulation. Overnight, the cyclone lingered just below major hurricane strength.

During the morning of September 16, Edouard strengthened into the first major hurricane of the 2014 Atlantic season, and in doing so reached its peak intensity of 115 mph winds and a central pressure of 955 mb. Meanwhile, the storm made its closest approach to Bermuda, passing just over 400 miles to the east as it began to curve towards the north and northeast that evening. As it encountered less favorable thermodynamic conditions, Edouard slowly decreased in convection and weakened. However, the circulation remained vigorous through September 17 as the system accelerated toward the northeast. That afternoon, Edouard's convective banding structure briefly became concentric, when an inner eyewall and a larger circular rain band beyond it. This resulted in a relatively gentle pressure gradient out from the center. Therefore, though the central pressure of the cyclone was quite low, its winds were only that of a category 1 hurricane.

As Edouard moved over progressively cooler water during the next day, however, the eyewall began to decay and gradual weakening continued. By late morning on September 18, the system had reached the north edge of a mid-level ridge, and was heading due east. It became a tropical storm that afternoon. Over the next day, wind shear increased significantly, stripping all convection from the circulation and displacing it to the southeast. By the afternoon of September 19, Edouard had become post-tropical.

The above image shows Hurricane Edouard on September 16, shorting after becoming the first major hurricane of the 2014 season.

During its time as a tropical cyclone, Edouard did not affect any landmasses.

Monday, September 1, 2014

Tropical Storm Dolly (2014)

Storm Active: September 1-3

A tropical wave formed over the Central Atlantic around August 23 and began to produced disorganized shower activity as it moved westward. Atmospheric conditions remained hostile for development along the path of the system for nearly a week as it moved generally westward into the Caribbean. Even as upper-level winds improved on August 30, the tropical wave began to interact with the Yucatan Peninsula, inhibiting further development. Convection increased the next day even as the center of the developing low pressure center moved over land. By September 1, the broad low pressure system had moved west-northwestward into the Bay of Campeche, where a tighter circulation appeared. Though the center had primarily left the deep convection behind over the Yucatan, the system was organized enough by that afternoon to be classified Tropical Depression Five.

Initially, the only significant rain band associated with Five was well south and east of the center of circulation, in part due to moderate wind shear out of the north-northwest. However, convection flared up near the center of circulation overnight. Meanwhile, the center itself underwent several reformations, shifting the position of the system significantly to the north. By the morning of September 2, organization had increased significantly, and the system strengthened into Tropical Storm Dolly. That afternoon, Dolly's instability continued as the center reformed once again, this time significantly south of its former position. This movement made the cyclone more symmetric, and the central pressure decreased to 1002 mb, a minimum for Dolly. Near midnight, the system made landfall in Mexico.

The main threat associated with Dolly was flooding rains, which portions of Mexico received in abundance, for even as Dolly rapidly weakened into a tropical depression during the morning of September 3, new rain bands continued to appear over water and move inland. 5-10 inches of rain were expected for much of the affected area, with up to 15 inches locally. The assembly line of moisture continued through the next few day even though Dolly dissipated within 12 hours of landfall, fueled in part by the nearby Hurricane Norbert in the East Pacific.

The above image shows Tropical Storm Dolly on September 2.

The above image shows the track of Dolly.

Sunday, August 24, 2014

Hurricane Cristobal (2014)

Storm Active: August 23-29

On August 16, some scattered thunderstorms developed in association with a broad low pressure system situated over the central tropical Atlantic, about halfway between the western coast of Africa and the Caribbean. No further organization occurred until around August 19, when convection became a little more concentrated in association with the system. As the low approached the Leeward Islands on August 21, it remained poorly defined, but began to generate gale force winds. Land interaction limited development over the next day while the low continued west-northwest just to the north of Puerto Rico and Hispaniola. However, on August 23, the system slowed in forward speed and turned northwest towards the Bahamas. That afternoon, though the circulation remained somewhat broad, banding on the north and east sides of the circulation improved to the point that advisories were initiated on Tropical Depression Four.

Some wind shear was affecting the system, but ocean waters near the Bahamas were very warm, and deep convection gradually increased near the center of circulation. By the morning of August 24, the depression had strengthened into Tropical Storm Cristobal. Over the next day, the system moved slowly northward, bringing sustained heavy rain to portions of the Bahamas. Though shear from the north exposed the circulation of Cristobal during the early morning of August 25, the center reformed southeast of its former position, bringing it closer to the convective canopy, and allowing modest strengthening through that morning.

During that day, the system meandered slowly to the north and east, moving away from the Bahamas. Meanwhile, though thunderstorm activity developed closer to the center, Cristobal's overall satellite presentation remind disorganized. The tropical storm was interacting with a frontal boundary, giving the associated convection a more linear than circular pattern. Despite this, winds increased that night and Cristobal became a category 1 hurricane. The system acquired a faster and more definite northward motion on August 26. Atmospheric conditions became more favorable over the next day, allowing Cristobal to develop a more organized, albeit asymmetric, structure. By the morning of August 27, the cyclone had developed a partial eyewall in the northwest semicircle. Though shower activity to the south and east was still scarce, small intensification accompanied this improvement in structure.

Around noontime, Cristobal passed well to the west of Bermuda, bringing scattered showers, gusty winds, and dangerous ocean conditions to the island. Influenced by mid-latitude winds, the system then began its turn towards the northeast, accelerating rapidly. At the same time, the cyclone assumed a more symmetrical appearance. As the hurricane raced to the north and east over the next day, it acquired an eyewall and even an intermittent eye feature during the afternoon and evening of August 28. Cristobal reached its peak intensity that night above 40°N, with 85 mph winds and a minimum pressure of 970 mb.

That evening, however, the system moved over much cooler water, and began extratropical transition as it moved northeast past Nova Scotia with a forward speed of nearly 50 mph. By the morning of August 29, all remaining convection was displaced well to the north of the center. Further, the wind field had broadened, indicating that the cyclone was no longer tropical. The low that had been Cristobal maintained powerful winds for several days, and eventually affected Iceland.

Hurricane Cristobal reached its peak intensity less than a day before extratropical transition, briefly developing a well-defined eye.

Cristobal recurved off of the east coast of the United States, and did not have a significant impact on any landmasses as a tropical cyclone.

Friday, August 1, 2014

Hurricane Bertha (2014)

Storm Active: July 31-August 6

On July 24, a tropical wave entered the east Atlantic. By July 27, a large area of disorganized shower activity had developed in the vicinity of the system. Convection continued to increase over the next two days, and a circulation became evident in the southeastern portion of the tropical wave early on July 29. Later that day, the low began a turn toward the west-northwest, and entered a drier air mass. Thunderstorm activity decreased markedly that night and into July 30. However, the circulation itself continued to become better defined and the low deepened into July 31. By this time, gale force winds were occurring in portions of the circulation, and only a lack of convection prevented the classification of the system as a tropical storm, since shower activity remained confined to the south and east of the center. Hurricane hunter aircraft which investigated the system noted winds up to 45 mph that afternoon near the center of circulation, even though these areas were devoid of thunderstorms. Finally, that evening, an area of convection appeared and persisted near the system's center, and advisories were initiated on Tropical Storm Bertha.

Even as Bertha entered a more moist and unstable atmosphere, promoting convective development, higher wind shear began to affect the system, restricting thunderstorm activity to the eastern half of the circulation. For a period on August 1, the center became completely exposed due to incoming shear, as Bertha's quick motion towards the west-northwest made it even more difficult for the cyclone to maintain convective coverage. Amidst these fluctuations, however, the circulation remained intact, and the storm entered the Caribbean Sea that afternoon. On August 2, heavy rain bands just north of Bertha affected Puerto Rico and the neighboring islands as the center passed to the south.

As interaction with land began that day, Bertha became even less organized, and a closed circulation was nearly undetectable, even on Doppler radar imagery. During the late afternoon, the system passed over the eastern Dominican Republic, bringing localized heavy rain and gusty winds. By this time, the cyclone had navigated around the southern edge of a ridge to its north, and therefore turned towards the northwest.

On August 3, Bertha brushed the easternmost Bahamas before moving away from land, and in addition away from hostile wind shear. For the first time since its formation, the tropical storm was able to develop healthy outflow and a central dense overcast near the center. When this occurred late that night, Bertha intensified rapidly: its central pressure dropped from 1012 to 999 mb in 12 hours, and winds approached hurricane strength. During the morning of August 4, through Bertha appeared quite disorganized on satellite imagery, a more intense eyewall and slight hints of an eye feature appeared at the center of circulation, even though there was no convection north of the eyewall! However poor the visual presentation, aerial data indicated that the cyclone now had hurricane force winds. Bertha thus reached its peak intensity as a category 1 hurricane with winds of 80 mph and a central pressure of 998 mb.

The system began to accelerate northward and north-northeastward that evening, and began to weaken as an oncoming frontal boundary greatly increased wind shear. By the morning of August 5, the center of circulation was intermittently exposed as thunderstorm activity was repeatedly displaced, and Bertha quickly lost strength, again becoming a tropical storm. Over the following day, the system weakened further and accelerated to the northeast away from the east coast of the United States. The system became extratropical on August 6.

Hurricane Bertha reached category 1 hurricane status (shown above) without much convective organization.

Bertha curved around the edge of a subtropical ridge and therefore missed landfall on the U.S. East Coast.

Tuesday, July 22, 2014

Tropical Depression Two (2014)

Storm Active: July 21-23

On July 16, a tropical wave emerged off of the coast of Africa. A few days later, the system began to show signs of development, the first tropical wave of the season to do so. On July 20, shower and thunderstorm activity increased in association with a low pressure center forming along the wave. Despite being over the open central Atlantic, where sea surface temperatures were hardly sufficient for convective development, the low continued to organize the next day as concentrated thunderstorms appeared about the center. By the afternoon of July 21, it became evident that the low had acquired a closed circulation, and advisories were initiated on Tropical Depression Two.

On July 22, as the system proceeded westward under the influence of a subtropical ridge, dry air began to affect the system from the north, limiting the small amount of deep convection associated with Two primarily to the southern and western quadrants. The depression became slightly more organized that evening as thunderstorm activity increased briefly in coverage and intensity. However, by the morning of July 23, wind shear had also begun to increase, and the circulation started to lose definition due to the hostile atmospheric conditions. A few hours later, it became evident that the circulation was no longer closed, indicating that Tropical Depression Two had degenerated into a trough of low pressure.

As evident in this satellite image, Tropical Depression Two experienced an invasion of dry air from the north throughout its short lifetime.

Tropical Depression Two degenerated into a tropical wave before reaching the Caribbean.

Sources: nhc.noaa.gov, http://commons.wikimedia.org/wiki/File:02-L_2014_track.png#mediaviewer/File:02-L_2014_track.png

Tuesday, July 1, 2014

Hurricane Arthur (2014)

Storm Active: June 30-July 5

On June 25, a frontal boundary oriented east to west over the northern United States began to push southward. Around June 27, a low pressure center formed along the front over North Carolina. Over the next day, the low drifted southeastward over South Carolina and emerged off of the coast early on June 28. Immediately, convection increased in association with the system.

In a region of weak steering currents, the low drifted slowly to the south, bringing rain showers to the northern Bahamas and eastern Florida by June 29. However, wind shear out of the north also increased that day, inhibiting the development of shower activity near the low's center. Despite this lack of convection, the low itself deepened significantly by June 30. Late in the day, upper-level winds once again became more favorable as wind shear dropped to near 10 kt. At this time, reconnaissance aircraft indicated that the system was just below the threshold of becoming a tropical cyclone. By just before midnight, organization had increased sufficiently to classify the system as Tropical Depression One, the first tropical cyclone of the 2014 Altantic Hurricane Season.

Tropical Depression One slowed and became nearly stationary off of the central Florida coast during the morning of July 1. Meanwhile, through the center of circulation remained on the northern edge of thunderstorm activity, banding and convective organization improved and the cyclone strengthened into Tropical Storm Arthur. Though the tropical storm reamined quite close to the U.S. East Coast, most of the deep convection was confined to the southern and eastern parts of the circulation, sparing land areas of the heaviest rain. Banding slowly improved throughout the day, indicating gradual strengthening By that evening, Arthur had begun a definite northward motion ahead of a trough moving into the southeastern United States. Central deep convection remained inconsistent into the morning of July 2, but the cyclone deepened and showed hints of an eye, and Arthur had soon intensified into a strong tropical storm.

Arthur persisted in its northerly motion throughout the day and most of the night, and meanwhile continued to strengthen. An eye feature made a brief appearance on visible satellite imagery during the afternoon of July 2, and the storm continued to gain in organization through the morning of July 3, even despite some ingestion of dry air from the north. By this time, rain bands had begun to sweep over the coasts of the Carolinas. Later in the morning, Arthur finally began to take its long anticipated eastward turn ahead of a front approaching the U.S. east coast and began to accelerate north-northeast.

That afternoon, Arthur developed a well-defined eye apparent on both visible and infrared imagery, indicating that another phase of strengthening was beginning. By the evening, the cyclone was upgraded to a category 2 hurricane. At 11:15 pm EDT on July 3, Hurricane Arthur made landfall near Cape Lookout, North Carolina, reaching its peak intensity of 100 mph winds and a minimum pressure of 973 mb, already stronger than any cyclone of the 2013 Atlantic hurricane season. Around 5:00 am on July 4, the center of circulation passed over the northern Outer Banks and emerged into the Atlantic. Meanwhile, the system's outer bands affected the coastal areas of Virginia, Maryland, Delaware, and New Jersey.

Increasing wind shear and colder waters began to weaken Arthur that morning, even as its windfield expanded, indicating that the extratropical transition had begun. Late on July 4, Arthur made its closest approach to Cape Cod as a minimal category 1 hurricane, bringing heavy rainfall and some tropical storm force winds to the region. By this time, Arthur was accelerating rapidly to the northeast and losing tropical characteristics. Early on June 5, the Arthur made landfall in southern Nova Scotia as the remaining deep convection became separated from the low-level center. The cyclone became post-tropical shortly afterward. The remnants of Arthur continued north and northeast over Newfoundland and into the North Atlantic near Greenland.

Hurricane Arthur was the first hurricane to make landfall in the United States since 2012.

Arthur took a rather unexpected shift to the west before landfall, bringing it inland over the Outer Banks of North Carolina.