Hurricane Arlene (1987) - Meteorological History

Meteorological History

Hurricane Arlene originated out of an area of low pressure associated with a decaying frontal system along the North Carolina coastline on August 8. Tracking towards the southeast in a gradual anticyclonic loop, the system slowly increased in organization and intensity. By August 10, the low neared the Bahamas but remained disorganized. The following day, while located over Andros Island, the National Hurricane Center (NHC) upgraded the system to a tropical depression, the third of the season, based on its appearance on satellite imagery.

Upon becoming a depression on August 10, the forward movement of the storm shifted to the northwest in response to an approaching trough off the Eastern United States and an elongated subtropical ridge to the south. The depression intensified into a tropical storm at 1800 UTC on August 11; however, operationally it was not upgraded until a reconnaissance mission by the hurricane hunters found flight-level winds of 50 mph (80 km/h). The storm tracked towards Bermuda along a trough of low pressure in the Atlantic Ocean.

Throughout August 13, the proximity of Arlene to the trough prevented significant development. Around 1500 UTC, the center of Arlene tracked about 55 mi (89 km) north of Bermuda. Several hours later, a ship near the center of the storm reported 75 mph (121 km/h) winds; however, due to the disorganized presentation of the storm, these winds were not considered to be representative of Arlene's true intensity. Over the following several days, the storm tracked around several low pressure systems. By August 15, Arlene traveled southeast before re-curving to the northeast on August 18. The intensity of the storm also continuously fluctuated during this period peaking at 65 mph (105 km/h) and was as low as 40 mph (64 km/h).

The northeast movement followed a passing short-wave trough on August 18; the forward motion of the storm also increased due to the trough. On August 20, the steering currents around Arlene collapsed, leading to the storm nearly stalling for 24 hours. During this period, the storm developed excellent outflow and intensified. Operationally, Arlene was upgraded to a hurricane at 2200 UTC on August 20 based on the appearance of an eye-feature on satellite imagery; however, post-storm analysis indicated that the storm did not attain hurricane-status until 0600 UTC on August 22. This occurred 14.5 days after its formation.

Upon attaining hurricane-status, Arlene rapidly tracked northward due to a strengthening area of high pressure near the Azores. Shortly after, the storm attained its peak intensity with winds of 75 mph (121 km/h) and a barometric pressure of 987 mbar (hPa). Continuing rapidly northward, the hurricane began to interact with a baroclinic zone over the cold waters of the north Atlantic. This resulted in the storm undergoing an extratropical transition which it completed by 0000 UTC on August 24. The extratropical remnants of the storm continued to track around the periphery of the high pressure system, turning towards the southeast the following day. By August 26, the storm became increasingly disorganized and hard to pinpoint on satellite imagery. The storm finally dissipated at 1800 UTC off the coast of Portugal that day.