Hurricane Danielle (1998)

Infobox Hurricane
Name=Hurricane Danielle
Type=hurricane
Year=1998
Basin=Atl
Image location=Hurricane Danielle 01 sept 1998 1858Z.jpg


Formed=August 24, 1998
Dissipated=September 3, 1998
1-min winds=90
Pressure=960
Da

Fatalities=None reported
Areas=Eastern Seaboard, northeastern United States, Canadian Maritimes, British Isles
Hurricane season=1998 Atlantic hurricane season

Hurricane Danielle was the third named storm, second hurricane, and fourth most intense storm of the active 1998 Atlantic hurricane season, and was a long-tracking Cape Verde-type hurricane across the Atlantic Ocean that originated off the African coastline on August 21, reaching its peak intensity of 105 mph (170 km/h) four times periodically in its track across the Atlantic. Following just days behind Hurricane Bonnie, Danielle remained offshore, although it came close to the continental United States. Although it did not make landfall or have significant impact on land as a hurricane, Danielle had a serious impact on the British Isles as an extratropical cyclone on September 6, where it caused significant erosion and high seas shortly before merging with another extratropical low near Ireland, resulting in the rescue of several people from difficult sea conditions and the evacuation of coastal beach areas in some places, including Cornwall. Fortunately, little damage was associated from the remnants of Danielle in the coastal British Isles. Aside from the British Isles, Danielle also delivered tropical storm-force winds to Bermuda, although it did little damage. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf]

Meteorological history

A Cape Verde-type hurricane marked by a persistent west-northwest motion for several days since it first formed, the origins of Danielle have been traced to a tropical wave that exited the western coast of Africa on August 21. Bearing an ill-defined circulation center amid a cyclonic cloud formation, deep convection began to cluster around the circulation within 24 hours, and Dvorak satellite presentation classifications were issued the following day around 1100 UTC. Shortly thereafter, convective organization improved as clusters of showers and cloudiness became more concentrated, and later, on August 24, the developing system was upgraded to Tropical Depression Four as the system was approximately convert|600|mi|km west-southwest of Cape Verde. Organization continued as the system continued to strengthen, and convective activity became more tightly wrapped around the center, and late on August 24, the system was upgraded to the fourth named storm of the season, Tropical Storm Danielle. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf]

Due to well-defined tropospheric outflow, Danielle's intensification trend continued; on August 25, a pinhole-type eye developed, and Danielle was upgraded to a hurricane. The system was quite compact, with tropical storm-force winds extending over an area slightly more than convert|100|nmi|km. With the small size aiding in further intensification of the well-established hurricane, satellite imagery indicated that Danielle continued to intensify to a first peak intensity of 105 mph (170 km/h) while about convert|900|nmi|km east of the Lesser Antilles on August 26. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf] After reaching its first peak intensity, southeasterly vertical wind shear disrupted Danielle's organization, and reconnaissance aircraft data on August 27 indicated that the system was not well-organized. However, despite a relatively high pressure of 993 mbar, the storm continued to maintain its intensity of 105 mph (170 km/h). This deviation from the wind-pressure relationship probably was probably due to the storm's small size. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf]

Significant further strengthening of Danielle continued to be hampered by moderate vertical shear, but the storm managed to gain a second 105 mph (170 km/h) peak indicated by aircraft data later on August 27. Afterwards, some weakening took place over the next few days, and the storm was barely a hurricane by August 30, likely due to the cool wake left by Hurricane Bonnie just days earlier. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf]

Danielle's persistent west-northwest motion continued as it neared the western periphery of the subtropical ridge on August 30, where it began to slow in speed. Continuing to lose speed, a turn to the northwest and north began, reaching its westernmost point on August 31. Reaching its third 105 mph (170 km/h) peak intensity, Danielle completed recurvature, and southwesterly flow ahead of an approaching trough off the eastern United States coastline began to accelerate Danielle northeast on September 1, briefly reaching a fourth and final peak intensity of 105 mph (170 km/h). After passing convert|200|nmi|km northwest of Bermuda the next day, Danielle began to lose tropical characteristics as the storm was centered approximately convert|200|nmi|km south of Cape Race, Newfoundland, still bearing hurricane-force winds. Danielle became an extratropical cyclone on September 4, then continued to move east to east-northeast across the Atlantic for the next two days, with gradual weakening taking place. It slowed in speed and turned northeast on September 6 while convert|300|nmi|km west of the British Isles, losing identity on September 8 while merging with another extratropical cyclone convert|200|nmi|km north of Iceland. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf]

Preparations

Danielle's track was well-forecast by the National Hurricane Center and computer models, and the storm's recurvature was predicted in advance. [http://stormcarib.com/danielle.htm] No warnings or watches were placed for the eastern United States coastline or Carolinas, but a tropical storm warning was issued for Bermuda on September 1 as the southern edge of Danielle affected the island, delivering tropical storm-force winds. [http://www.nhc.noaa.gov/1998danielle.html]

Impact

Danielle delivered minimal impact to the mainland United States, but it brought sustained tropical storm-force winds of convert|35|kn|km/h, along with gusts to convert|47|kn|km/h, to Bermuda while passing to the north of the island on September 2. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf]

While passing near the British Isles on September 6 as an extratropical storm, Danielle delivered severe sea conditions to the western part of the isles. Erosion became a problem in some areas, and many people were rescued from rough seas. Coastal portions of Cornwall were evacuated as high waves broke over the tops of homes, and an all-terrain police vehicle was shoved into the sea by a rogue wave in the Isles of Scilly. No direct deaths, however, occurred in the British Isles, and no significant damage was reported. [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf]

Retirement

Because damage from the storm was minimal, the name Danielle was not retired in the spring of 1999, so it was reused again in 2004 and its on the list for the 2010 Atlantic hurricane season.

See also

* List of tropical cyclones

External links

* [http://www.aoml.noaa.gov/general/lib/lib1/nhclib/mwreviews/1998.pdf Monthly Weather Review, 1998]
* [http://www.nhc.noaa.gov/1998danielle.html National Hurricane Center report on Danielle]