Subtropical Storm Alpha (1972)
Encyclopedia
Subtropical Storm Alpha was a rare off-season subtropical cyclone
that hit Georgia
in May 1972. It developed from a previously non-tropical cyclone in the western Atlantic Ocean, and initially it moved northeastward off of the Carolinas. The storm turned southwestward due to a building ridge, and concurrently it intensified to become Subtropical Storm Alpha. It later moved ashore near Savannah
, and it finally dissipated in the northeast Gulf of Mexico on May 29. It produced wave action and moderate rainfall along the coast, and although there was no damage reported, there were two associated deaths.
. The origins of Alpha were from a surface low northeast of Florida, associated with the larger-scale, cold core upper low. It organized, and late on May 23 it could be classified as a subtropical
depression, east of the Georgia
/South Carolina
border. While southeast of Hatteras, North Carolina
, a developing ridge blocked its northeast motion, and so it slowed to turn to the southeast. On May 25, a small, intense low-level center organized rapidly, and by the next day it attained gale force winds, by which time the storm turned southwestward. At 1600 UTC on May 26, the National Hurricane Center
initiated advisories on Subtropical Cyclone Alpha, when the storm was about 225 miles south of Cape Hatteras
. Around that time, it reached its peak winds of 70 mph (110 km/h).
On its first advisory, there was disagreement among forecast models regarding its eventual track, with projected tracks deviating from a Georgia landfall to a track northeastward out to sea. Alpha was also a climatological outlier at the time; the NHC HURRAN model, which was based on previous storms with similar characteristics, found no analogs for the storm. Subtropical Storm Alpha was initially well-defined as it moved southwestward. The very small center was located along the eastern edge of the convection, while low-level cloud bands formed east of the center. At the time, the temperature structure was more typical of a winter storm, although it was expected to become more like a subtropical storm typical during the summer months. The winds decreased steadily as it turned more westward on May 27, and the heavy rainfall persisted mostly to the north and west of the center.
The National Hurricane Center initially thought the center might not have been at the surface, and the agency indicated low confidence, as they could not determine a circulation center. The difficulty arose from the large, sprawling nature of the storm, and by later on May 27 a new center formed, as confirmed by radar imagery and the Hurricane Hunters
. That night, the extremely small center made landfall just south of Savannah, Georgia
, affecting a very small area with winds of 65 mph (100 km/h) and a minimum pressure of 991 mbar (hPa; 29.26 inHg). Around the time of landfall, Alpha developed a warm core, indicating some tropical characteristics. The storm weakened quickly over land, although it did not dissipate until two days later over the northeast Gulf of Mexico.
from Jacksonville, Florida
to Cape May, New Jersey
. Gale warnings were posted from Cape Fear, North Carolina to Chincoteague, Virginia
. The interaction between Alpha and the high pressure system to its northeast caused cooler temperatures and gusty winds from Delaware southward. Wave heights reached up to 20 feet (6.1 m) along the Virginia capes. The storm dropped rainfall along the coast of North Carolina and Virginia, with a maximum of 6.97 inches (177 mm) reported in Ocracoke, North Carolina
.
While the storm was traveling over the western Atlantic Ocean, the storm produced a large area of rough seas, which was considered the greatest threat from the storm. Beach erosion and heavy swells were described as likely to occur as far south as Palm Beach, Florida
, and along the northern coasts of the Bahamas. In northeastern Florida, police officers were stationed to ensure people did not swim in the dangerous seas. The high waves also halted work to deepen a harbor at the Mayport Naval Station. Two people drowned after the storm dissipated, when surf was still turbulent. Tides along the Georgia coast reached 2 to 3 ft (0.6096 to 0.9144 m) above normal, which caused some flooding. Wind gusts reached 58 mph (93.3 km/h) on Saint Simons Island
. Moderate rains spread in coastal areas from South Carolina through southern Florida. No damage was reported.
The 1972 hurricane season was the first year in which quasi-tropical cyclones were named, by using the NATO phonetic alphabet. At the time, the names were applied to large subtropical cyclone
s and small neutercanes, both of which were later combined into one category. Consequently, it was the first subtropical cyclone to be named. Alpha was also a fairly rare May storm, one of only 22 tropical or subtropical cyclones on record in the month.
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...
that hit 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...
in May 1972. It developed from a previously non-tropical cyclone in the western Atlantic Ocean, and initially it moved northeastward off of the Carolinas. The storm turned southwestward due to a building ridge, and concurrently it intensified to become Subtropical Storm Alpha. It later moved ashore near Savannah
Savannah, Georgia
Savannah is the largest city and the county seat of Chatham County, in the U.S. state of Georgia. Established in 1733, the city of Savannah was the colonial capital of the Province of Georgia and later the first state capital of Georgia. Today Savannah is an industrial center and an important...
, and it finally dissipated in the northeast Gulf of Mexico on May 29. It produced wave action and moderate rainfall along the coast, and although there was no damage reported, there were two associated deaths.
Meteorological history
Throughout May 1972, a series of weak troughs moved across the eastern United States. In the third week of the month, an upper-level cutoff low developed along one of these troughs, located southeast of the United States and removed from the WesterliesWesterlies
The Westerlies, anti-trades, or Prevailing Westerlies, are the prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east, and steer extratropical...
. The origins of Alpha were from a surface low northeast of Florida, associated with the larger-scale, cold core upper low. It organized, and late on May 23 it could be classified as a subtropical
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...
depression, east of the 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...
/South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
border. While southeast of Hatteras, North Carolina
Hatteras, North Carolina
Hatteras is an unincorporated community in Dare County, North Carolina, United States, on the Outer Banks island of Hatteras. North Carolina Highway 12 passes through the community linking it to Frisco and Ocracoke . It is south of the famous Cape Hatteras and the Cape Hatteras Lighthouse in Buxton...
, a developing ridge blocked its northeast motion, and so it slowed to turn to the southeast. On May 25, a small, intense low-level center organized rapidly, and by the next day it attained gale force winds, by which time the storm turned southwestward. At 1600 UTC on May 26, 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...
initiated advisories on Subtropical Cyclone Alpha, when the storm was about 225 miles south of Cape Hatteras
Cape Hatteras
Cape Hatteras is a cape on the coast of North Carolina. It is the point that protrudes the farthest to the southeast along the northeast-to-southwest line of the Atlantic coast of North America...
. Around that time, it reached its peak winds of 70 mph (110 km/h).
On its first advisory, there was disagreement among forecast models regarding its eventual track, with projected tracks deviating from a Georgia landfall to a track northeastward out to sea. Alpha was also a climatological outlier at the time; the NHC HURRAN model, which was based on previous storms with similar characteristics, found no analogs for the storm. Subtropical Storm Alpha was initially well-defined as it moved southwestward. The very small center was located along the eastern edge of the convection, while low-level cloud bands formed east of the center. At the time, the temperature structure was more typical of a winter storm, although it was expected to become more like a subtropical storm typical during the summer months. The winds decreased steadily as it turned more westward on May 27, and the heavy rainfall persisted mostly to the north and west of the center.
The National Hurricane Center initially thought the center might not have been at the surface, and the agency indicated low confidence, as they could not determine a circulation center. The difficulty arose from the large, sprawling nature of the storm, and by later on May 27 a new center formed, as confirmed by radar imagery and the 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...
. That night, the extremely small center made landfall just south of Savannah, Georgia
Savannah, Georgia
Savannah is the largest city and the county seat of Chatham County, in the U.S. state of Georgia. Established in 1733, the city of Savannah was the colonial capital of the Province of Georgia and later the first state capital of Georgia. Today Savannah is an industrial center and an important...
, affecting a very small area with winds of 65 mph (100 km/h) and a minimum pressure of 991 mbar (hPa; 29.26 inHg). Around the time of landfall, Alpha developed a warm core, indicating some tropical characteristics. The storm weakened quickly over land, although it did not dissipate until two days later over the northeast Gulf of Mexico.
Preparations and impact
At the time of the first advisory on Alpha, there were small craft warningsSmall 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....
from Jacksonville, Florida
Jacksonville, Florida
Jacksonville is the largest city in the U.S. state of Florida in terms of both population and land area, and the largest city by area in the contiguous United States. It is the county seat of Duval County, with which the city government consolidated in 1968...
to Cape May, New Jersey
Cape May, New Jersey
Cape May is a city at the southern tip of Cape May Peninsula in Cape May County, New Jersey, where the Delaware Bay meets the Atlantic Ocean and is one of the country's oldest vacation resort destinations. It is part of the Ocean City Metropolitan Statistical Area. As of the 2010 United States...
. Gale warnings were posted from Cape Fear, North Carolina to Chincoteague, Virginia
Chincoteague, Virginia
Chincoteague is a town on Chincoteague Island in Accomack County, Virginia, United States. The population was 4,317 at the 2000 census. The town is perhaps best known for the Chincoteague Ponies, although these are not actually on the island of Chincoteague but on nearby Assateague Island...
. The interaction between Alpha and the high pressure system to its northeast caused cooler temperatures and gusty winds from Delaware southward. Wave heights reached up to 20 feet (6.1 m) along the Virginia capes. The storm dropped rainfall along the coast of North Carolina and Virginia, with a maximum of 6.97 inches (177 mm) reported in Ocracoke, North Carolina
Ocracoke, North Carolina
Ocracoke is a census-designated place and unincorporated town located at the southern end of Ocracoke Island, located entirely within Hyde County, North Carolina. The population was 769 as of the 2000 census...
.
While the storm was traveling over the western Atlantic Ocean, the storm produced a large area of rough seas, which was considered the greatest threat from the storm. Beach erosion and heavy swells were described as likely to occur as far south as Palm Beach, Florida
Palm Beach, Florida
The Town of Palm Beach is an incorporated town in Palm Beach County, Florida, United States. The Intracoastal Waterway separates it from the neighboring cities of West Palm Beach and Lake Worth...
, and along the northern coasts of the Bahamas. In northeastern Florida, police officers were stationed to ensure people did not swim in the dangerous seas. The high waves also halted work to deepen a harbor at the Mayport Naval Station. Two people drowned after the storm dissipated, when surf was still turbulent. Tides along the Georgia coast reached 2 to 3 ft (0.6096 to 0.9144 m) above normal, which caused some flooding. Wind gusts reached 58 mph (93.3 km/h) on Saint Simons Island
St. Simons, Georgia
St. Simons is a census-designated place located on St. Simons Island in Glynn County, Georgia, United States. Both the community and the island are commonly considered to be one location, known simply as "St. Simons Island", or locally as "The Island". St...
. Moderate rains spread in coastal areas from South Carolina through southern Florida. No damage was reported.
The 1972 hurricane season was the first year in which quasi-tropical cyclones were named, by using the NATO phonetic alphabet. At the time, the names were applied to large subtropical cyclone
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...
s and small neutercanes, both of which were later combined into one category. Consequently, it was the first subtropical cyclone to be named. Alpha was also a fairly rare May storm, one of only 22 tropical or subtropical cyclones on record in the month.
See also
- 1972 Atlantic hurricane season1972 Atlantic hurricane seasonThe 1972 Atlantic hurricane season officially began on June 1, 1972, and lasted until November 30, 1972. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. A strong El Niño kept hurricane activity at a minimum, and in fact the season...
- Timeline of the 1972 Atlantic hurricane seasonTimeline of the 1972 Atlantic hurricane seasonThe 1972 Atlantic hurricane season is one of four Atlantic hurricane seasons not to have any major hurricanes, the others being the 1968 season, the 1986 season, and the 1994 season. During the season, seven tropical or subtropical depressions formed, all of which became tropical or subtropical...
- List of Florida hurricanes (1950–1974)