Preliminary Report
Hurricane Florence
02 - 08 November 1994

1994 PRELIMINARY REPORTS

Tropical Storm Alberto (TS)
Tropical Storm Beryl (TS)
Hurricane Chris (1)
Tropical Storm Debby (TS)
Tropical Storm Ernesto (TS)
Hurricane Florence (2)
Hurricane Gordon (1)

a. Synoptic History

Hurricane Florence developed from a low-pressure system that formed at the end of October along a stationary frontal band about 1000 nautical miles to the east-southeast of Bermuda. The low gradually acquired a closed circulation when the portion of the front in its vicinity dissolved during the first day or two of November.

A curved band of deep convection developed to the north through northeast of the low on the 2nd of November. Ship reports indicate that the system's strongest surface winds were then associated with a distant portion of the convective band, about 200 nautical miles to the northeast of the center. These features are characteristic of a subtropical cyclone, as indicated in early satellite "Classifications" of this system by the NHC Tropical Satellite Analysis and Forcast (TSAF) unit and NESDIS Synoptic Analysis Branch (SAB). It is estimated that the cyclone became a subtropical depression at 0000 UTC on the 2nd of November. Ship reports of 40 mph winds in the convective band support designating the system a subtropical storm for part of the day on the 2nd and 3rd.

The distant area of convection weakened on the 3rd and ship reports suggest that maximum wind speeds decreased to about 35 mph. However, deep convection then became concentrated near the circulation center and the system made a transition from subtropical to tropical. Dvorak technique estimates from the TSAF unit and SAB reached T2.5 at 0000 UTC on the 4th and it is estimated that the cyclone became Tropical Storm Florence at that time.

Florence moved toward the northwest at about 9 mph before turning toward the north at a decreased speed on the 6th. Although upper-level outflow was restricted to the south, the cyclone strengthened early in this period. Satellite pictures revealed a partially developed eye for the first time around 1700 UTC on the 4th and the system reached hurricane strength about that time. The eye was occasionally noted but analyses of satellite pictures implied no significant change in strength over the following three days. The only reconnaissance mission in Florence, near 1800 UTC on the 6th, encountered 83 mph maximum winds at a flight level of about 10,000 feet, and a central pressure of 982 mb.

The hurricane was located about 700 nautical miles to the east of Bermuda when it reached the westernmost point of its track near 0600 UTC on the 7th. The hurricane had become nearly stationary at that point. It then turned toward the northeast and accelerated in response to a large and powerful mid-latitude storm that approached Florence from the Canadian maritime provinces. Only 24-30 hours later, the associated steering currents were moving Florence toward the northeast at nearly 52 mph.

A distinct eye surrounded by moderately deep convection was seen on satellite pictures on the 7th and the hurricane is estimated to have reached its peak intensity of 109 mph and 972 mb central pressure at 0000 UTC on the 8th. Florence was then within a narrowing sector of warm air between the large storm to its northwest and another to the northeast. The eye diameter widened from about 20 to 30-35 nautical miles. The eye remained apparent until about 1800 UTC, when Florence began moving over water temperatures below 20°C, and was overtaken and absorbed by the rapidly-moving cold front previously located to its northwest.

b. Meteorological Statistics

The maximum intensity inferred from application of Dvorak technique to satellite imagery was about 86-104 mph for Florence. However, this technique (unlike the Hebert-Poteat method for subtropical systems) does not include an adjustment to the wind speed that accounts for the translational speed of exceptionally fast moving cyclones. The estimated best track maximum intensity of 109 mph for Florence on the 8th incorporates an attempt to make a reasonable adjustment for that characteristic. There were no surface obervations to corfirm or reject this estimate.

c. Casualty and Damage Statistics

Florence did not directly affect land and the NHC received no reports of damages or casualties.