Tropical Storm Ophelia (2005)

Hurricane Ophelia was a long-lived tropical cyclone in September 2005 that moved along an erratic path off the East Coast of the United States for much of its existence. The fifteenth named storm and the eighth hurricane of the record-breaking 2005 Atlantic hurricane season, Ophelia originated from a complex set of systems across the Atlantic in early September. An area of low pressure consolidated near the Bahamas and was classified as Tropical Depression Sixteen on September 6. Stuck in a region of meager steering currents, largely dominated by a lull between two ridges to the north and east, this system moved along a looping course with a general northward trajectory. The following day it organized into Tropical Storm Ophelia and soon reached hurricane status on September 8. Over the next week, Ophelia's intensity oscillated between tropical storm and hurricane levels due to intrusions of dry air, varying levels of wind shear, and gradual upwelling of cooler waters along its meandering path. Gradually growing in size, the system reached hurricane strength for the fourth time and its peak strength on September 14, with maximum sustained winds of 85 mph (140 km/h). By this time Ophelia had completed a second loop and was moving northwest toward North Carolina. Changing direction once again, the system turned away from the state though its eyewall scraped the coastline for two days. The system degraded to tropical storm strength for a final time on September 16 as it began accelerating northeast. Becoming embedded within the westerlies, Ophelia transitioned into an extratropical cyclone the next day. Remaining on a steady east-northeast to northeast path for the next week, Ophelia traversed Atlantic Canada and the northern Atlantic Ocean before dissipating on September 23 over the Norwegian Sea.

Ophelia's erratic track prompted warnings and watches for a large swath of the Eastern Seaboard, ultimately a greater area than necessary. With the storm occurring on the heels of Hurricane Katrina, state governments were quick to prepare shelters out of an abundance of caution. National Guard servicemen were deployed to North Carolina while thousands more were on standby there and in South Carolina. More than 2,000 people used public shelters as Ophelia approached land. As the hurricane's core remained largely offshore, its impacts were significantly less than feared. Some coastal locales saw heavy rain, notably more than in the Outer Banks of North Carolina. The greatest impacts were felt in North Carolina, where more than 240,000 people lost power and more than 1,500 homes were damaged. Total monetary losses in the state were estimated at $70 million. Extensive beach erosion occurred due to the hurricane's prolonged effects. Tropical storm-force wind gusts and heavy rain caused minor damage in Florida, Massachusetts, and South Carolina. Rough seas led to one fatality in Florida and left another person missing in South Carolina while rain-slicked roads contributed to a fatal accident in North Carolina. Atlantic Canada saw negligible effects as Ophelia's remnants traversed the region; one person died after falling from his roof while preparing for the storm. In the storm's wake, 37 of North Carolina's counties were declared disaster areas. The Federal Emergency Management Agency provided roughly $5.2 million in public assistance and the National Guard assisted with distribution of relief supplies.

Meteorological history

Background

The 2005 Atlantic hurricane season was the most active on record at the time by numerous metrics, with 28 tropical or subtropical storms forming throughout the year. It also proved to be a ruinous year, with thousands of fatalities and more than $100 billion in damage. Above-normal sea surface temperature anomalies, averaging in the western tropical Atlantic and Caribbean Sea contributed to the development of these storms. The Climate Prediction Center determined four primary factors driving the season's activity: the Atlantic multidecadal oscillation, the reduction of atmospheric convection in the tropical Pacific, record-high sea surface temperatures in the tropical Atlantic and Caribbean, and conducive wind and pressure patterns across the western Caribbean and Gulf of Mexico. Additionally, the El Niño–Southern Oscillation (ENSO) was in a neutral phase, lowering the likelihood of storms making landfall on the East Coast of the United States and leading to a concentration of impacts farther west. September saw considerable activity, with five hurricanes developing.

Origins

On September 1, 2005, a cold front emerged off the East Coast of the United States and propagated southeast. The system became increasingly elongated into a trough over the following days, eventually extending from near the Florida Peninsula east to the edge of Tropical Depression Lee east of Bermuda. By September 4, two defined areas of low pressure consolidated along the trough: one south of Bermuda that would later become Hurricane Nate and the second near the Bahamas which would become Hurricane Ophelia. Forecasters at the National Hurricane Center (NHC) described the dual lows as a "complex scenario" and stated that possible tropical cyclogenesis would be slow to occur. Initially drifting south, the latter system reversed course on September 5 as convection organized around the low within an area of favorable upper-level conditions. Based on satellite data and synoptic observations, the NHC estimated that Tropical Depression Sixteen formed around 06:00 UTC on September 6 between Andros and Grand Bahama. Winds at Freeport and Settlement Point reached 30 mph (45 km/h). Situated within a region of weak steering currents, the depression drifted generally north and later north-northwest, crossing Grand Bahama around 16:00 UTC. Wind shear displaced convection north of the broad center as it traversed the northern Bahamas. Initially, the system consisted of three defined mesoscale convective systems (MCS) spanning an area across, each producing areas of heavy rain. Throughout September 6, the MCSs congealed into a single spiral rainband and the precursor to an eyewall.

Fluctuation in strength and track

Early in the storm's lifecycle, meteorologists struggled with a complex track forecast as models depicted a wide-range of scenarios for the depression. Some models took the system into the Gulf of Mexico and others kept the system off the coast of the Southeastern United States. The cyclone was stuck between two lobes of the subtropical ridge to the north as a strong trough moved off the eastern United States. The system became more organized on September 7 and intensified into Tropical Storm Ophelia approximately 115 mi (185 km) east-southeast of Cape Canaveral, Florida. This marked the earliest formation of a season's fifteenth named storm. This record was later tied by Hurricane Nate in 2011 and subsequently broken by Tropical Storm Omar on September 1, 2020. Becoming embedded within a broad trough extending from Florida, through Ophelia and Nate, and all the way east to Hurricane Maria over the central Atlantic, Ophelia executed a slow counter-clockwise loop. During this time it steadily intensified as banding features coalesced around the storm. High sea surface temperatures of fueled bursts of deep convection throughout September 8. Following the formation of an eyewall and well-defined upper-level outflow, Ophelia intensified into a hurricane around 21:00 UTC on September 8 with sustained winds reaching 75 mph (120 km/h).

The hurricane's prolonged lack of movement resulted in the upwelling of cooler waters which in turn caused it to weaken back to a tropical storm early on September 9. Later on September 9, Ophelia began moving slowly northeast in response to a mid-latitude trough. The storm soon developed a wide eye and regained hurricane status around 18:00 UTC. Soon thereafter, increasing wind shear and intrusions of dry air into the hurricane's core caused degradation of its structure. However, Ophelia's structure once again improved late on September 10 with a 35 mi (55 km) wide eye developing; this coincided with it regaining hurricane status for the third time. Concurrently, it attained its lowest central pressure of 976 mbar (hPa; 28.82 inHg). Over the next two days the hurricane executed a clockwise loop within an area of weak steering between two ridges. Its slow movement led to further upwelling of cooler waters even over the relatively warm Gulf Stream. Gradual degradation of the hurricane's structure occurred as it looped back to the west-southwest, with meager convection unable to maintain vertical mixing. Sea surface temperatures beneath the system had plummeted to an average of by this time, and with insufficient heat content convection within the eyewall collapsed. Slightly warmer waters farther from the center helped support a broken ring around the decaying center. By 00:00 UTC on September 12, Ophelia weakened back to a tropical storm for the third time. An unusual eyewall replacement cycle commenced with its inner core dissipating and a larger eye organizing around it; its radius of maximum wind doubled from about to . This differed from classical replacement cycles as Ophelia never displayed defined concentric eyewalls, rather the inner one degraded as the outer one formed. After completing the two-day-long loop, the storm proceeded along a slow northwest and later northward trajectory toward the Carolinas.

North Carolina impact and extratropical transition

After remaining largely steady-state from September 12 into the early part of September 13, convection became increasingly organized as it moved back over the Gulf Stream. Maintaining a broad circulation, the storm's smaller core rotated erratically within it while the overall system progressed steadily north. Ophelia regained hurricane strength for a fourth and final time early on September 14. The system displayed an increasingly organized eye once again and expansive outflow aloft. The ridge previously halting the hurricane's northward motion began accelerating off the New England coastline; however, westerly flow in its wake would not be strong enough to induce significant acceleration of Ophelia. Accordingly the hurricane began an "excruciatingly long passage" along the shores of North Carolina. Throughout September 14, the storm's eye expanded to a diameter of 60 mi (95 km). A more defined inner eyewall featured small vortices which enhanced the vertical mixing of winds. Around 12:00 UTC it attained maximum sustained winds of 85 mph (140 km/h), the highest during its existence. Over the next two days, the hurricane's eyewall scraped the North Carolina coastline bringing hurricane-force winds to these areas. A station at Cape Lookout measured a peak two-minute sustained wind of while an unverified gust of was reported in Davis. Ophelia once again became caught between two ridges on September 15 as it turned east. Over a two-day period, Ophelia's eyewall impacted areas from Wilmington to Morehead City. The combination of dry air coming from land and cooler shelf waters caused convection on the hurricane's west side to collapse; its proximity to the Gulf Stream enabled it to maintain convection elsewhere in its circulation. Ophelia pulled away from North Carolina early on September 16 as it weakened to a tropical storm for the final time.

The storm accelerated east late on September 16 as it became embedded within the mid-latitude westerlies. An approaching baroclinic wave over the Great Lakes also induced a northward component to Ophelia's track. Increasing shear displaced convection north of its center and caused its core to become vertically tilted. After a brief resurgence in convection, Ophelia began transitioning into an extratropical cyclone on September 17 as it interacted with an approaching trough. Its surface center became increasingly separated from the strongest winds and thunderstorm activity. During this time the storm made its closest approach to Massachusetts, passing 70 mi (110 km) to the southeast of Cape Cod. Ophelia completed its extratropical transition by 00:00 UTC on September 18 as it approached Nova Scotia. The system remained just offshore, with its center scraping the coast of Guysborough County in the eastern portion of the island. It then traversed the Cabot Strait before making landfall in south-central Newfoundland around 18:00 UTC with maximum winds of 50 mph (85 km/h). Ophelia traversed the island within six hours, emerging over the north Atlantic Ocean by September 19. The cyclone continued along an east-northeast to northeast path for several days as it spun down. Ophelia ultimately dissipated on September 23 over the Norwegian Sea.

Research

As part of their annual Hurricane Field Program, the National Oceanic and Atmospheric Administration (NOAA) conducts research flights into tropical cyclones to study internal mechanics and improve forecasts. Part of the Frequent-Monitoring Experiment under the broader Intensity Forecasting Experiment (IFEX), Ophelia was extensively documented throughout its lifecycle. As such, 462 dropsondes were deployed in the storm between September 6 and 17, the second-most in a single storm during 2005, only behind the 503 dropped into Hurricane Rita later in September. The Naval Research Laboratory in conjunction with NOAA conducted research flights into the tropical depression that became Ophelia on September 6. Additional flights were made as part of The Hurricane Rainband and Intensity Change Experiment (RAINEX). The multitude of recon flights during the developmental stages of Ophelia provided detailed data that supported the first in-depth study of the role of mesoscale convective systems in the genesis of tropical cyclones. As part of a joint project between NOAA and Aerosonde Ltd, an AAI Aerosonde unmanned aerial vehicle was flown into the outer bands of Hurricane Ophelia on September 16. This was the first such mission conducted into a tropical cyclone. Flying at an altitude of , the vehicle measured peak winds of . A concurrent NOAA Hurricane Hunter mission corroborated the vehicle's measurements, and the project was considered a success. This was followed two weeks later by the first successful Aerosonde core penetration of a tropical cyclone within Typhoon Longwang near Taiwan. The final research mission into Ophelia was conducted on September 17, focusing on its extratropical transition. A collaborative effort between NOAA and Canada's Atmospheric Environment Service, two recon missions were flown into the storm to study structural changes during this transitory period. This marked the first detailed dynamic core structure of such a system.

Preparations

Throughout the existence of Hurricane Ophelia, the NHC, Canadian Hurricane Center (CHC), and Bahamas Department of Meteorology issued numerous tropical cyclone warnings and watches between September 6 and 17. The hurricane's erratic movement led to watches and warnings being issued for a much larger region than necessary across the East Coast of the United States, with some forecasts calling for landfalls that did not verify.

United States

With gas prices already elevated because of Hurricane Katrina's effects in the Gulf of Mexico, gas prices fluctuated due to disruptions from Hurricane Ophelia. Prices initially rose in the southeast as the system was developing before dropping as the storm turned away from Florida. They later rose in Maine as the system impacted North Carolina.

Florida

Already suffering from a volley of six hurricane impacts since 2004, concerns were raised over Ophelia's potential effects in Florida. With an uncertain track, the main issue presented was beach erosion, especially in areas significantly affected by Hurricanes Frances and Jeanne in 2004. Ophelia was the first major beach erosion event to test the $30 million shoreline restoration in Brevard County. A public shelter was opened in Daytona Beach, Volusia County; only 13 people used the shelter and were relocated to a Red Cross facility. Schools in the county were closed on September 8 over flooding concerns. Fourteen ships departed Naval Station Mayport to avoid the storm. Florida Fish and Wildlife Conservation Commission search and rescue teams previously sent to Mississippi returned to the state. Mariners as far west as Tallahassee were advised of possible adverse conditions. Shipment of the Space Shuttle external tank to NASA's Vehicle Assembly Building at the Kennedy Space Center was delayed in order to protect the equipment. The tank was originally meant to be delivered to a facility in New Orleans but that structure was closed indefinitely due to damage from Hurricane Katrina. Concerns over flooding were raised in Polk County with areas already heavily saturated ahead of the storm. Pumping of water into Lake Rosalie was authorized by the South Florida Water Management District, but the pumps were unlikely to arrive in time. Similarly, water levels at Lake Griffin, Rock Lake, and Lake Irish in Seminole County were elevated and posed a flood risk.

The Carolinas

The South Carolina Emergency Management Division advised residents in flood-prone areas to remain abreast of the storm. Forecasts on September 10 indicated Ophelia would strike South Carolina and local emergency management officials held meetings to discuss preparations. Governor Mark Sanford requested the Federal Emergency Management Agency (FEMA) suspend transport of Katrina refugees to the receiving centers in Charleston and Colombia. Any potential evacuees from Ophelia would be directed to hotels in the Midlands. Although 1,650 members of the South Carolina National Guard were already deployed on anti-terror missions and Katrina-related relief, 7,100 remained in reserve if needed. Eighty-five state troopers were deployed to coastal areas to assist local police. The Red Cross opened shelters on September 10 in the Lowcountry, but closed them the following day due to lack of use. Charleston County also opened public shelters before the issuance of any evacuation orders. Voluntary evacuation orders were issued for barrier islands, coastal residents, those living in mobile homes, and people living in flood-prone areas of Horry and Georgetown counties on September 13. The Red Cross opened three shelters across both counties; only 25 people used them. Statewide, approximately 2,000 people sought refuge across 45 shelters. Horry County officials revised evacuation procedures in light of the large loss of life from Katrina in the Gulf Coast, with emphasis placed on relocating poor, sick, and elderly persons. Schools in Georgetown and Horry counties closed while Coastal Carolina University and Horry-Georgetown Technical College suspended classes. Football and volleyball matches between Charleston Southern University and The Citadel on September 12 were postponed. The Cougar Classic golf tournament at Yeamans Hall Club teed off early due to the storm.

North Carolina Governor Mike Easley declared a state of emergency on September 10. Flood concerns were high along Pamlico Sound and the Neuse River where a storm surge of was forecast. Low-lying areas along the Neuse River in particular were severely impacted by Hurricane Isabel in 2003. Mandatory evacuation orders were issued for the approximately 800 tourists on Ocracoke Island

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