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
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"
Fig. 1 [14K GIF])
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 25 knots 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 40 knot 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
The best track was obtained from the data presented in Figs.
2 (11K GIF) and 3 (12K GIF). Those figures show Grace's
estimated central pressure and maximum one-minute wind speed, respectively, versus time.
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
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.
d. Forecast and Warning Critique
Grace was a tropical storm for about 30 hours. This is too short
a period to provide a meaningful quantitative evaluation of forecast accuracy.
Hurricane and tropical storm watches and warnings were neither
issued nor necessary.