On November 27, a surface storm with gale-force winds developed beneath an upper-level low pressure area, about 1150 mi (1850 km) east of Bermuda.
At the time, a cold front extended eastward from the surface storm toward the eastern Atlantic Ocean, north of Tropical Storm Delta.
By that time, tropical cyclone forecast models anticipated the possible development of a subtropical cyclone, and although they were inconsistent, National Hurricane Center (NHC) specialist Eric Blake stated, "blocking at high latitudes seems to favor another subtropical cyclone effort."
The blocking referred to a ridge stretching across the northern Atlantic.
The surface storm gradually separated from the frontal zone, but initially its convection, or thunderstorm activity, was sparse and poorly organized.
The NHC introduced the system in its tropical weather outlook on November 28, with the possibility of subtropical or tropical development noted.
It moved slowly westward, becoming better organized, and by late that day resembled a subtropical cyclone; however, as it was still connected to the cold front, it could not have been classified as such.
Early on November 29, an area of deep convection developed and organized over the surface center when it was about 915 mi (1470 km) east of Bermuda.
The NHC accordingly assessed the system as developing into a tropical storm, designating it with the Greek letter Epsilon.
Operationally, the NHC did not initiate advisories until 1500 UTC on November 29, about nine hours after it actually developed.
By that time, the convection had wrapped into a ring 45 mi (72 km) in diameter.
In the first advisory on Epsilon, the NHC forecast steady strengthening to near hurricane status due to marginally favorable conditions, followed by extratropical transition within five days; an alternate possibility was Epsilon being absorbed by a larger extratropical storm.

Epsilon moved westward after its development, steered by a ridge to its north.
Initially, Epsilon was embedded beneath an upper-level low that provided an area of low wind shear and instability.
An eye-like feature briefly developed in the center of the convection, although the thunderstorms waned late on November 28 due to restricted inflow.
However, banding features and outflow improved at the same time.
By November 30, the NHC anticipated extratropical transition to occur within two days, although some strengthening was still expected.
That day, there was an increase in convection over the center and the development of a ragged eye-feature.
The winds briefly increased to 65 mph (105 km/h), although the intensity of the thunderstorms diminished.
Initially Epsilon was predicted to continue westward and eventually turn to the north and northeast.
Instead, it turned toward the southwest and executed a cyclonic loop; the unexpected motion caused larger than normal errors in the extended track forecast.
As it moved to the south, the storm crossed over an area of warmer water temperatures, and the NHC remarked that "just a modest increase in convection [would be] needed to make Epsilon a hurricane."
At the time, forecasters assessed the winds in Epsilon to be around 70 mph (115 km/h), although in a post-season re-analysis it was found to have been 10 mph (15 km/h) weaker.
Late on November 30, Epsilon made its closest approach to Bermuda, passing about 645 miles (1045 km) east-southeast of the island.

Tropical Storm Epsilon began its motion to the east and northeast on December 1, due to an approaching trough.
Its structure became that of a "shallow hybrid-type tropical cyclone", and an eye-feature again developed within the convection.
At the time, the NHC and several computer models anticipated extratropical transition within 36 hours as it accelerated northeastward near the Azores.
However, four computer models predicted an alternate scenario, and forecaster Stacy Stewart stated such transition would only occur "barring any southward motion over warmer water that would prolong both the lifetime of Epsilon and the 2005 Atlantic hurricane season."
As it continued
On November 27, a surface storm with gale-force winds developed beneath an upper-level low pressure area, about 1150 mi (1850 km) east of Bermuda. At the time, a cold front extended eastward from the surface storm toward the eastern Atlantic Ocean, north of Tropical Storm Delta. By that time, tropical cyclone forecast models anticipated the possible development of a subtropical cyclone, and although they were inconsistent, National Hurricane Center (NHC) specialist Eric Blake stated, "blocking at high latitudes seems to favor another subtropical cyclone effort." The blocking referred to a ridge stretching across the northern Atlantic. The surface storm gradually separated from the frontal zone, but initially its convection, or thunderstorm activity, was sparse and poorly organized. The NHC introduced the system in its tropical weather outlook on November 28, with the possibility of subtropical or tropical development noted. It moved slowly westward, becoming better organized, and by late that day resembled a subtropical cyclone; however, as it was still connected to the cold front, it could not have been classified as such. Early on November 29, an area of deep convection developed and organized over the surface center when it was about 915 mi (1470 km) east of Bermuda. The NHC accordingly assessed the system as developing into a tropical storm, designating it with the Greek letter Epsilon. Operationally, the NHC did not initiate advisories until 1500 UTC on November 29, about nine hours after it actually developed. By that time, the convection had wrapped into a ring 45 mi (72 km) in diameter. In the first advisory on Epsilon, the NHC forecast steady strengthening to near hurricane status due to marginally favorable conditions, followed by extratropical transition within five days; an alternate possibility was Epsilon being absorbed by a larger extratropical storm.
Epsilon moved westward after its development, steered by a ridge to its north. Initially, Epsilon was embedded beneath an upper-level low that provided an area of low wind shear and instability. An eye-like feature briefly developed in the center of the convection, although the thunderstorms waned late on November 28 due to restricted inflow. However, banding features and outflow improved at the same time. By November 30, the NHC anticipated extratropical transition to occur within two days, although some strengthening was still expected. That day, there was an increase in convection over the center and the development of a ragged eye-feature. The winds briefly increased to 65 mph (105 km/h), although the intensity of the thunderstorms diminished. Initially Epsilon was predicted to continue westward and eventually turn to the north and northeast. Instead, it turned toward the southwest and executed a cyclonic loop; the unexpected motion caused larger than normal errors in the extended track forecast. As it moved to the south, the storm crossed over an area of warmer water temperatures, and the NHC remarked that "just a modest increase in convection [would be] needed to make Epsilon a hurricane." At the time, forecasters assessed the winds in Epsilon to be around 70 mph (115 km/h), although in a post-season re-analysis it was found to have been 10 mph (15 km/h) weaker. Late on November 30, Epsilon made its closest approach to Bermuda, passing about 645 miles (1045 km) east-southeast of the island.
Tropical Storm Epsilon began its motion to the east and northeast on December 1, due to an approaching trough. Its structure became that of a "shallow hybrid-type tropical cyclone", and an eye-feature again developed within the convection. At the time, the NHC and several computer models anticipated extratropical transition within 36 hours as it accelerated northeastward near the Azores. However, four computer models predicted an alternate scenario, and forecaster Stacy Stewart stated such transition would only occur "barring any southward motion over warmer water that would prolong both the lifetime of Epsilon and the 2005 Atlantic hurricane season." As it continued
Hurricane Epsilon