Hurricane Lisa 1998

Preliminary Report
Hurricane Lisa
05 - 10 October 1998


Tropical Storm Alex (TS)
Hurricane Bonnie (3)
Tropical Storm Charley (TS)
Hurricane Danielle (2)
Hurricane Earl (2)
Tropical Storm Frances (TS)
Hurricane Georges (4)
Tropical Storm Hermine (TS)
Hurricane Ivan (1)
Hurricane Jeanne (2)
Hurricane Karl (2)
Hurricane Lisa (1)
Hurricane Mitch (5)
Hurricane Nicole (1)

Lisa briefly reached hurricane force in the central North Atlantic Ocean and did not affect land.


a. Synoptic History

Lisa originated from a tropical wave which moved westward from Africa into the eastern tropical Atlantic Ocean on 29 September. The associated cloudiness was fairly well organized and centered at about 10°N latitude. By the next day, it was an almost indistinguishable part of the Intertropical Convergence Zone(ITCZ) which was active across the entire tropical Atlantic. By 3 October, the system became better defined as its convection increased and the ITCZ cloudiness dissipated to its east and west. On the 4th, midway between Africa and the Lesser Antilles, there were signs of a low level circulation and it is estimated that a tropical depression formed at 0000 UTC on the 5th.

The depression strengthened into Tropical Storm Lisa on the 5th, although it was in an environment of strong vertical shear, as evidenced by the low-level center being exposed to the west of the associated deep convection. This shear was caused by an upper level low located to the northwest of the storm. The presence of this low also weakened the ridge to the north, causing the storm's motion to begin a turn toward the north. During the next two days, a strong baroclinic trough in the westerlies evolved into a deep low in the central North Atlantic. This resulted in an acceleration toward the northeast. The forward speed reached in excess of 58 mph by the afternoon of the 9th. The vertical shear relaxed over the storm and it gradually strengthened. Lisa turned northward on the 9th, steered by the deep low to its west and a 1032 mb high to its east. This strong east-west pressure gradient also resulted in increasing the surface winds well to the east of the center and Lisa briefly strengthened to a 75-mph hurricane on the 9th, before merging with an extratropical frontal system in the far North Atlantic. On the 10th, it was no longer possible to identify a well-defined circulation on satellite imagery.

b. Meteorological statistics

A NOAA drifting buoy (16.6N, 46.9W) in the central tropical Atlantic provided a wind observation of 40 mph at 0850 UTC on the 5th and another of 41 mph at 2138 UTC. These observations were essential in determining that Lisa had become a tropical storm, as satellite-based intensity estimates were well below storm strength at these times. The estimate that Lisa acquired 75-mph hurricane-force winds on the 9th was based on satellite intensity estimates and on a report of 70 mph from the ship ZCBD9 located at 46.9N, 33.3W at 1800 UTC (approximately 240 nautical miles east of the center). The system was rapidly transforming into an extratropical system during this time and it is not certain that the strongest winds were near the center.

c. Casualty and damage statistics

There were no reports of casualties or damage received.

Maximum Intensity For Hurricane Lisa
05 - 10 October, 1998

Position Pressure
Wind Speed
Lat. (°N) Lon. (°W)
09/1200 41.6 38.7 995 75 Category 1 Hurricane