Tropical Storm Hallie (1975)
Encyclopedia
Tropical Storm Hallie was a tropical storm during October 1975 that existed as three types of cyclones: subtropical
, tropical
, and extratropical
. The eighth and final named storm of the 1975 Atlantic hurricane season
, Hallie formed on October 24 from the complex interaction of several weather systems. Initially a subtropical depression, it tracked northeast parallel to the coast of the Southeast United States, and obtained fully tropical characteristics on October 26. Hallie ultimately peaked as a moderate tropical storm before being absorbed by a frontal zone
late on October 27. Damage from the storm was minimal, and was limited to light precipitation and slightly above-average tides.
moved off the East Coast of the United States
and entered the western Atlantic Ocean on October 18, 1975. The southern portion of the system became stationary near the Bahamas; simultaneously, a cut-off upper-level low pressure area
formed in the same region. The disturbance remained stationary while producing clouds and shower activity for several days. At the same time, a tropical wave
moved westward across the Atlantic, and by October 23, part of the wave had merged with the disturbance over the Bahamas. The resultant storm developed into a subtropical depression
on October 24, while centered approximately 100 mi (160.9 km) east of Daytona Beach, Florida
.
The depression started drifting to the north on October 25, while developing tropical characteristics
. Tracking roughly parallel to the coast, the cyclone maintained its general northward track until October 26, when it lost its subtropical characteristics and intensified into a tropical storm, receiving the name Hallie. At the time of designation, Hallie was situated about 100 mi (160.9 km) east of Charleston, South Carolina
. Hallie accelerated to the northeast during the next 24 hours. On October 27, it attained its peak intensity with winds of 50 mph (80.5 km/h) and minimum central pressure
of 1002 millibars. The storm merged with a frontal zone and became extratropical
later that day off the coast of Virginia
.
On October 27, gale warning
s were issued for portions of the Outer Banks
of North Carolina
, and small craft advisories
were posted for coastal areas from Georgia
to Virginia. Tides along the North Carolina and Virginia coasts generally ran 1 to 2 ft (0.3048 to 0.6096 m) above normal. Light to moderate rainfall was reported, peaking at 2.55 in (64.8 mm) in Manteo, North Carolina
. Additionally, the pressure gradient
between Hallie and a high pressure system over the United States generated increased winds across much of the East Coast. Roughly 10,000 people were threatened by the tropical storm, none of whom needed to be evacuated. However, because the storm remained primarily offshore, damage was minimal, and no fatalities were reported.
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
, tropical
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
, and 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...
. The eighth and final named storm of the 1975 Atlantic hurricane season
1975 Atlantic hurricane season
The 1975 Atlantic hurricane season officially began on June 1, 1975, and lasted until November 30, 1975. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin...
, Hallie formed on October 24 from the complex interaction of several weather systems. Initially a subtropical depression, it tracked northeast parallel to the coast of the Southeast United States, and obtained fully tropical characteristics on October 26. Hallie ultimately peaked as a moderate tropical storm before being absorbed by a frontal zone
Weather front
A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front...
late on October 27. Damage from the storm was minimal, and was limited to light precipitation and slightly above-average tides.
Meteorological history
A frontal troughWeather front
A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front...
moved off the East Coast of the United States
East Coast of the United States
The East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...
and entered the western Atlantic Ocean on October 18, 1975. The southern portion of the system became stationary near the Bahamas; simultaneously, a cut-off upper-level low pressure area
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
formed in the same region. The disturbance remained stationary while producing clouds and shower activity for several days. At the same time, a tropical wave
Tropical 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 westward across the Atlantic, and by October 23, part of the wave had merged with the disturbance over the Bahamas. The resultant storm developed into a subtropical depression
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
on October 24, while centered approximately 100 mi (160.9 km) east of Daytona Beach, Florida
Daytona Beach, Florida
Daytona Beach is a city in Volusia County, Florida, USA. According to 2008 U.S. Census Bureau estimates, the city has a population of 64,211. Daytona Beach is a principal city of the Deltona – Daytona Beach – Ormond Beach, Florida Metropolitan Statistical Area, which the census bureau estimated had...
.
The depression started drifting to the north on October 25, while developing tropical characteristics
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
. Tracking roughly parallel to the coast, the cyclone maintained its general northward track until October 26, when it lost its subtropical characteristics and intensified into a tropical storm, receiving the name Hallie. At the time of designation, Hallie was situated about 100 mi (160.9 km) east of Charleston, South Carolina
Charleston, South Carolina
Charleston is the second largest city in the U.S. state of South Carolina. It was made the county seat of Charleston County in 1901 when Charleston County was founded. The city's original name was Charles Towne in 1670, and it moved to its present location from a location on the west bank of the...
. Hallie accelerated to the northeast during the next 24 hours. On October 27, it attained its peak intensity with winds of 50 mph (80.5 km/h) and minimum central pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
of 1002 millibars. The storm merged with a frontal zone and became 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...
later that day off the coast of Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
.
Preparations and impact
The precursor to Hallie produced extensive cloudiness precipitation through the Bahamas.On October 27, gale warning
Gale warning
A gale warning is a warning issued by weather services in maritime locations about the existence of winds of gale force or above or the imminent occurrence of gales at sea...
s were issued for portions of the Outer Banks
Outer Banks
The Outer Banks is a 200-mile long string of narrow barrier islands off the coast of North Carolina, beginning in the southeastern corner of Virginia Beach on the east coast of the United States....
of North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
, and small craft advisories
Small craft advisory
A small craft advisory is a type of warning issued by the National Weather Service in the United States, most frequently in coastal areas. It is issued when winds have reached, or are expected to reach within 12 hours, a speed marginally less than gale force....
were posted for coastal areas from Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
to Virginia. Tides along the North Carolina and Virginia coasts generally ran 1 to 2 ft (0.3048 to 0.6096 m) above normal. Light to moderate rainfall was reported, peaking at 2.55 in (64.8 mm) in Manteo, North Carolina
Manteo, North Carolina
Manteo is a town in Dare County, North Carolina, United States, located on Roanoke Island. The population was 1,052 at the 2000 census. It is the county seat of Dare County.-Geography:...
. Additionally, the pressure gradient
Pressure gradient
In atmospheric sciences , the pressure gradient is a physical quantity that describes in which direction and at what rate the pressure changes the most rapidly around a particular location. The pressure gradient is a dimensional quantity expressed in units of pressure per unit length...
between Hallie and a high pressure system over the United States generated increased winds across much of the East Coast. Roughly 10,000 people were threatened by the tropical storm, none of whom needed to be evacuated. However, because the storm remained primarily offshore, damage was minimal, and no fatalities were reported.
See also
- List of Atlantic hurricanes
- List of North Carolina hurricanes (1950–1979)