Preliminary Report
Tropical Storm Grace
14 - 17 October 1997

1997 PRELIMINARY REPORTS

Tropical Storm Ana (TS)
Hurricane Bill (1)
Tropical Storm Claudette (TS)
Hurricane Danny (1)
Hurricane Erika (3)
Tropical Storm Fabian (TS)
Tropical Storm Grace (TS)

a. Synoptic History

Tropical Storm Grace developed from one of several lows that developed along a frontal trough extending east-northeastward from the western Caribbean Sea to the central North Atlantic Ocean. Surface observations indicate that the extratropical low that became Grace was initially centered just north of Hispaniola, and that it reached gale strength near 0000 UTC on 15 October. One day later, a large area of deep convection developed over or just northeast of the low-level circulation center. This is the basis for indicating in the post-storm "best track" that the system transformed into a tropical cyclone at 0000 UTC on the 16th. The system did not shed all of its extratropical characteristics, however. Most notably, the circulation remained elongated along the frontal trough and a band of deep convection appeared to link Grace to another low-pressure center with gale-force winds that was located about 500 nautical miles to the east-northeast.

Grace developed in an environment of southwesterly vertical wind shear generally to the south of a large extratropical cyclone south of Newfoundland. The associated steering currents accelerated Grace to about 29 mph on an east-northeast to northeast heading. The limited available ship reports and intensity estimates based on satellite pictures suggest that Grace was at its strongest, with 46 mph winds, at the time that it became a tropical cyclone. The storm appeared to slowly weaken thereafter and, on the morning of the 17th, deep convection dissipated. This revealed a weak and diffuse low-level circulation that, over the course of about a day, became indistinguishable from the frontal trough in which it was embedded.

b. Meteorological Statistics

Position and intensity estimates were obtained from analyses of satellite pictures by NOAA's Synoptic Analysis Branch (SAB) and Tropical Analysis and Forecast Branch (TAFB), and by the Air Force Global Weather Center (AFGWC). The analyses also included surface observations.

There were no observations of tropical storm force winds associated with the tropical cyclone phase of Grace.

c. Casualty and Damage Statistics

Grace did not directly affect land and no reports of casualties or damages were received.